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Model 3120B

Printed in Mexico

M08-0224-000   

11/10

IMPORTANT! PLEASE READ CAREFULLY AND SAVE.

This user’s manual contains important information about your Smoke

Alarm’s operation. If you are installing this Smoke Alarm for use by 

others, you must leave this manual—or a copy of it—with the end user.

INTRODUCTION

Thank you for choosing First Alert

®

for your Smoke Alarm needs. You have 

purchased a state of the art Smoke Alarm designed to provide you with an

early warning of a fire. Please take the time to read this manual and make

this Smoke Alarm an integral part of your family’s safety plan.

Key Features of the 3120B Photo & Ion Combo Smoke Alarm:
Photo & Ion Smoke Sensors: 
Dual photoelectric and ionization smoke 

sensing technologies for optimal sensing of smoke particles produced in

both flaming and smoldering fires.
Optipath 360 Technology

TM

Patented technology provides 360˚ of direct

access to the smoke sensor.
Two Silence Features: Low Battery Silence temporarily silences low 

battery chirp for up to eight hours before replacing low battery. 

Alarm Silence silences an unwanted alarm for several minutes.
Two Latching Features: Alarm Latch remembers which unit initiated an

alarm. 

Low Battery Latch visually identifies which unit is in low battery 

condition.
Perfect Mount: Mounting bracket keeps alarm secure over a wide rotation

range to allow for perfect alignment.
Battery back-up: Keeps alarm functioning during a power interruption 

provided batteries are fresh and installed properly.
© 2010 BRK Brands, Inc. All rights reserved. Distributed by BRK Brands, Inc.

3901 Liberty Street Road, Aurora, IL 60504-8122

Consumer Affairs: (800) 323-9005

www.firstalert.com   •   www.brkelectronics.com

FIRE SAFETY TIPS

Follow safety rules and prevent hazardous situations: 1) Use smoking 

materials properly. Never smoke in bed. 2) Keep matches or lighters away 

from children; 3) Store flammable materials in proper containers; 

4) Keep electrical appliances in good condition and don’t overload electrical

circuits; 5) Keep stoves, barbecue grills, fireplaces and chimneys grease- 

and debris-free; 6) Never leave anything cooking on the stove unattended; 

7) Keep portable heaters and open flames, like candles, away from flammable

materials; 8) Don’t let rubbish accumulate.
Keep alarms clean, and test them weekly. Replace alarms immediately if they

are not working properly. Smoke Alarms that do not work cannot alert you to a

fire. Keep at least one working fire extinguisher on every floor, and an additional

one in the kitchen. Have fire escape ladders or other reliable means of escape

from an upper floor in case stairs are blocked.

BEFORE YOU INSTALL THIS SMOKE ALARM

IMPORTANT! Read “Recommended Locations for Smoke Alarms” and

“Locations to Avoid for Smoke Alarms” before beginning. This unit monitors

the air, and when smoke reaches its sensing chamber, it alarms. It can give

you more time to escape before fire spreads. This unit can ONLY give an early

warning of developing fires if it is installed, maintained and located where

smoke can reach it, and where all residents can hear it, as described in this

manual. This unit will not sense gas, heat, or flame. It cannot prevent or 

extinguish fires.
Understand The Different Type of Smoke Alarms

Battery powered or electrical? Different Smoke Alarms provide different

types of protection. See “About Smoke Alarms” for details.

Know Where To Install Your Smoke Alarms

Fire Safety Professionals recommend at least one Smoke Alarm on every

level of your home, in every bedroom, and in every bedroom hallway or

separate sleeping area. See “Recommended Locations For Smoke Alarms”

and “Locations To Avoid For Smoke Alarms” for details.

Know What Smoke Alarms Can and Can’t Do

A Smoke Alarm can help alert you to fire, giving you precious time to

escape. It can only sound an alarm once smoke reaches the sensor. 

See “Limitations of Smoke Alarms” for details.

Check Your Local Building Codes

This Smoke Alarm is designed to be used in a typical single-family home. 

It alone will not meet requirements for boarding houses, apartment 

buildings, hotels or motels. See “Special Compliance Considerations” 

for details.

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All First Alert

®

and BRK

®

Smoke Alarms conform to regulatory 

requirements, including UL217 and are designed to detect particles of

combustion. Smoke particles of varying number and size are produced

in all fires.

Ionization technology is generally more sensitive than photoelectric

technology at detecting small particles, which tend to be produced

in greater amounts by flaming fires, which consume combustible

materials rapidly and spread quickly. Sources of these fires may include

paper burning in a wastebasket, or a grease fire in the kitchen.

Photoelectric technology is generally more sensitive than ionization

technology at detecting large particles, which tend to be produced in

greater amounts by smoldering fires, which may smolder for hours

before bursting into flame. Sources of these fires may include cigarettes

burning in couches or bedding.
For maximum protection, use both types of Smoke Alarms on each

level and in every bedroom of your home.

USER’S MANUAL

SMOKE ALARMS

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

• This unit will not alert hearing impaired residents. It is recom-

mended that you install special units which use devices like

flashing strobe lights to alert hearing impaired residents.

• Installation of this unit must conform to the electrical codes in 

your area; Articles 210 and 300.3 (B) of NFPA 70 (NEC), NFPA 72,

NFPA 101; SBC (SBCCI); UBC (ICBO); NBC (BOCA); OTFDC (CABO),

and any other local or building codes that may apply. Wiring and

installation must be performed by a licensed electrician. Failure to

follow these guidelines may result in injury or property damage.

• This unit must be powered by a 24-hour, 120VAC pure sine wave

60Hz circuit. Be sure the circuit cannot be turned off by a switch,

dimmer, or ground fault circuit interrupter. Failure to connect this

unit to a 24-hour circuit may prevent it from providing constant

protection.

• This Smoke Alarm must have AC or battery power to operate.

If the AC power fails, battery back-up will allow the alarm to

sound for at least 4 minutes. If AC power fails and the battery is

weak, protection should last for at least 7 days. If AC power fails

and the battery is dead or missing, the alarm cannot operate.

• Never disconnect the power from an AC powered unit to stop an

unwanted alarm. Doing so will disable the unit and remove your

protection. In the case of a true unwanted alarm open a window

or fan the smoke away from the unit. The alarm will reset auto-

matically when it returns to normal operation. Never remove the

batteries from a battery operated unit to stop an unwanted alarm

(caused by cooking smoke, etc.). Instead open a window or fan

the smoke away from the unit. The alarm will reset automatically.

• Connect this unit ONLY to other compatible units. See “How To

Install This Smoke Alarm” for details. Do not connect it to any

other type of alarm or auxiliary device. Connecting anything else

to this unit may damage it or prevent it from operating properly.

• This Smoke Alarm has a battery drawer which resists closing

unless a battery is installed. This warns you the unit will not

operate under DC power without a battery.

• Do not stand too close to the unit when the alarm is sounding. 

It is loud to wake you in an emergency. Exposure to the horn at

close range may harm your hearing.

• Do not paint over the unit. Paint may clog the openings to the

sensing chambers and prevent the unit from operating properly.

The Mounting Bracket:

To remove the mounting bracket from the Smoke

Alarm base, hold the Smoke Alarm base firmly 

and twist the mounting bracket counterclockwise.

The mounting bracket installs onto the junction box.

It has a variety of screw slots to fit most boxes.

The Power Connector: 

The power connector plugs into a power input block on

the Smoke Alarm. It supplies the unit with AC power.

• The black wire is “hot.” 
• The white wire is neutral.
• The orange wire is used for interconnect.

If you need to remove the power connector, turn 

POWER OFF first. Insert a flat screwdriver blade

between the power connector and the security tab

inside the power input block. Gently pry back the tab

and pull the connector free.

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The Parts of This Unit
1

Mounting Bracket

2

Mounting Slots

3

Locking Pins (break out of bracket)

4

Hot (Black) AC Wire

5

Neutral (White) AC Wire

6

Interconnect (Orange) Wire

7

Quick-Connect Power Connector

8

Turn this way to remove from bracket

9

Turn this way to attach to bracket

10 Slide-Out Battery Drawer

The basic installation of this Smoke Alarm is similar whether you want to

install one Smoke Alarm, or interconnect more than one Smoke Alarm. 

If you are interconnecting more than one Smoke Alarm, you MUST read

“Special Requirements For Interconnected Smoke Alarms” below before

you begin installation.

ELECTRICAL SHOCK HAZARD. Turn off power to the area where you 

will install this unit at the circuit breaker or fuse box before beginning

installation. Failure to turn off the power before installation may result 

in serious electrical shock, injury or death.
1. Remove the mounting bracket from the base, and attach it to the 

junction box.
Activate the battery back-up by removing the “Pull to Activate Battery

Back-Up” tab. Or, install battery back-up. Battery back-up cannot work

until you install the battery in the correct position (Match “+” to “+” and

“-” to “-”).
Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

2. Using wire nuts, connect the power connector to the household wiring.

3. Plug the power connector into the back of the Smoke Alarm.
4. Position the base of the Smoke Alarm over the mounting bracket and

turn. The Alarm can be positioned over the bracket every 90°.

Turn the Smoke Alarm clockwise (right) until the unit is in place.

5. Check all connections.

Improper wiring of the power connector or the wiring leading to the

power connector will cause damage to the Alarm and may lead to a

non-functioning Alarm.

ELECTRICAL SHOCK HAZARD. Do not restore power until all Smoke

Alarms are completely installed. Restoring power before installation is

complete may result in serious electrical shock, injury or death.
6. Make sure the Smoke Alarm is receiving AC power. Under normal 

operation, the Green power indicator light will shine continuously. 

7. If the Green power indicator light does not light, 

TURN OFF POWER 

TO THE JUNCTION BOX and recheck all connections. If all connections

are correct and the Green power indicator still does not light when you

restore the power, the unit should be replaced immediately.

8. Test each Smoke Alarm. Press and hold the Test/Silence button until the

unit alarms. 

When testing a series of interconnected units you must

test each unit individually. Make sure all units alarm when each one

is tested.

Continued...

8. Continued

If any unit in the series does not alarm, 

TURN OFF POWER and recheck

connections. If it does not alarm when you restore power, replace it 

immediately.

Special Requirements For Interconnected Smoke Alarms

• Failure to meet any of the above requirements could damage the

units and cause them to malfunction, removing your protection.

• AC and AC/DC Smoke Alarms can be interconnected. Under AC

power, all units will alarm when one senses smoke. When power 

is interrupted, only the AC/DC units in the series will continue to

send and receive signals. AC powered Smoke Alarms will not

operate.

Interconnected units can provide earlier warning of fire than stand-alone units,

especially if a fire starts in a remote area of the dwelling. If any unit in the series

senses smoke, all units will alarm. To determine which Smoke Alarm initiated an

alarm, see table:

During an Alarm:
On Initiating Alarm(s)

Red LED(s) flashes (flash) rapidly

On All Other Alarms

Red LED is Off

After an Alarm (Latching):
On Initiating Alarm(s)

Red LED(s) flash 3 times, spaced one second apart. 

The pattern repeats approximately every 45 seconds.

On All Other Alarms

Green LED(s) On, Red LED(s) Off

Interconnect units within a single family residence only. Otherwise all 

households will experience unwanted alarms when you test any unit in the

series. Interconnected units will only work if they are wired to compatible

units and all requirements are met. This unit is designed to be compatible

with: 

First Alert

®

Smoke Alarm Models SA4120, SA4121B, SA100B, SA520

and 

BRK

®

Smoke Alarm Models 3120B, 9120, 9120B, SC6120B, SC9120B,

7010, 7010B, 7010BSL, 7020B, SC7010B, SC7010BV, 100S, 4120, 4120B,

4120SB; 

BRK

®

CO Alarm Models CO5120BN, CO5120PDBN; BRK

®

Heat

Alarm Models HD6135F and HD6135FB; BRK

®

Auxiliary Devices Models

RM3 and RM4 (Relay Modules), SL177 (Strobe Light). 

See www.brkelectronics.com for most current interconnect list.

Interconnected units must meet ALL of the following requirements:

• A maximum of 18 compatible units may be interconnected 

(Maximum of 12 Smoke Alarms).

• The same fuse or circuit breaker must power all interconnected units.
• The total length of wire interconnecting the units should be less than

1000 feet (300 meters). This type of wire is commonly available at

Hardware and Electrical Supply stores.

• All wiring must conform to all local electrical codes and NFPA 70 (NEC).

Refer to NFPA 72, NFPA 101, and/or your local building code for further 

connection requirements.

HOW TO INSTALL THIS SMOKE ALARM

THE PARTS OF THIS SMOKE ALARM

This Smoke Alarm is designed to be mounted on any standard wiring junction box up to a 4-inch (10 cm) size, on either the ceiling or wall (if allowed by local codes).

Read “Recommended Locations For Smoke Alarms” and “Locations to Avoid For Smoke Alarms” before you begin installation. 

Tools you will need:  • Needle-nose pliers or utility knife • Standard Flathead screwdriver.

FOLLOW THESE INSTALLATION STEPS

STAND-ALONE ALARM ONLY:

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Tuck the orange wire inside the junction box. It is used for interconnect

only.

INTERCONNECTED UNITS ONLY:
Strip off about 1/2” (12 mm) of the plastic coating on the orange wire

on the power connector.

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Connect the orange wire on the power connector to the interconnect

wire in the junction box. Repeat for each unit you are interconnecting.

Never connect the hot or neutral wires in the junction box to the orange

interconnect wire. Never cross hot and neutral wires between Alarms.

STAND-ALONE ALARM ONLY:

If you are only installing one Smoke Alarm, restore power to the 

junction box.

INTERCONNECTED UNITS ONLY:

If you are interconnecting multiple Smoke Alarms, repeat steps 

1-5 for each Smoke Alarm in the series. When you are finished,

restore power to the junction box.

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A. Unswitched 120VAC 

60 Hz source

B. To additional units; Maximum = 18 total

(Maximum 12 Smoke Alarms)

1. Smoke Alarm
2. Ceiling or Wall
3. Power Connector

4. Wire Nut
5. Junction Box
6. Neutral Wire (Wht)

7. Interconnect Wire

(Orange)

8. Hot Wire (Blk) 

4

OPTIONAL LOCKING FEATURES

The locking features are designed to discourage unauthorized removal of the batteries or Alarm. It is not necessary to activate the locks in single-family 

households where unauthorized battery or Alarm removal is not a concern.
These Smoke Alarms have two separate locking features: one to lock the battery compartment, and the other to lock the Smoke Alarm 

to the mounting bracket. You can choose to use either feature independently, or use them both.
Tools you will need: • Needle-nose pliers or utility knife  • Standard Flathead screwdriver.
Both locking features use locking pins, which are molded into the mounting bracket. Using needle-nose pliers or a utility knife, remove

one or both pins from the mounting bracket, depending on how many locking features you want to use.

To permanently remove either lock, insert a flathead screwdriver between the locking pin and the lock, and pry the pin out of the lock.

TO LOCK THE BATTERY COMPARTMENT

Do not lock the battery compartment until you have installed the 

batteries and tested the battery back-up.
1. Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

If the unit does not alarm during testing, DO NOT lock the battery

compartment! Install new batteries and test again. If the Smoke 

Alarm still does not alarm, replace it immediately.

2. Using needle-nose pliers or a utility knife, detach one locking pin 

from the mounting bracket.

3. Push the locking pin through the hole near the battery drawer on the

back of the Smoke Alarm.

TO UNLOCK THE BATTERY COMPARTMENT

Once the Smoke Alarm is installed, you must disconnect it from the AC power

before unlocking the battery compartment.

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse box.

Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.
1. Remove the Smoke Alarm from the mounting

bracket. If the unit is locked to the bracket, see

the section “To Unlock the Mounting Bracket.”

2. Disconnect the power connector by gently prying

it away from the back of the Smoke Alarm.

3. Insert a flathead screwdriver under the head 

of the locking pin, and gently pry it out of the 

battery compartment lock. (If you plan to relock

the battery compartment, save the locking pin.)

4. To relock the battery compartment, close the 

battery door and reinsert locking pin in lock.

5. Reconnect the power connector to the back of the Smoke Alarm, reattach

the Smoke Alarm to the mounting bracket, and restore the power.

When replacing the batteries, always test the Smoke Alarm before relocking

the battery compartment.

TO UNLOCK THE MOUNTING BRACKET

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.

1. Insert a flathead screwdriver between the

mounting bracket pin and the mounting bracket.

2. Pry the Smoke Alarm away from the bracket by

turning both the screwdriver and the Smoke

Alarm counterclockwise (left) at the same time.

TO LOCK THE MOUNTING BRACKET

1. Using needle-nose pliers, detach one locking pin from mounting bracket.

2. Insert the locking pin into the lock located

opposite from the battery drawer as shown

in the diagram.

3. When you attach the Smoke Alarm to the mounting bracket, the locking

pin’s head will fit into a notch on the bracket.

Locking Features (Continued)

Printed in Mexico   M08-0224-000   

11/10

First Alert

®

is a registered trademark of the First Alert Trust.

BRK

®

is a registered trademark of BRK Brands, Inc.

WEEKLY TESTING

NEVER use an open flame of any kind to test this unit. You might

accidentally damage or set fire to the unit or to your home. The built-

in test switch accurately tests the unit’s operation as required by

Underwriters Laboratories, Inc. (UL).

If the Alarm ever fails to test properly, replace it immediately.

Products under warranty may be returned to the manufacturer 

for replacement. See “Limited Warranty” at the end of this manual.

DO NOT stand close to the Alarm when the horn is sounding. Exposure

at close range may be harmful to your hearing. When testing, step away

when horn starts sounding.
It is important to test this unit every week to make 

sure it is working properly. Using the test button is the

recommended way to test this Smoke Alarm.
Press and hold the Test/Silence button on the cover of the

unit until the alarm sounds (the unit may continue to alarm

for a few seconds after you release the button). If it does

not alarm, make sure the unit is receiving power and test 

it again. If it still does not alarm, replace it immediately.
During testing, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause. LED flashes once every second.
When testing a series of interconnected units you must test each unit 

individually. Make sure all units alarm when each one is tested.

REGULAR MAINTENANCE

Use only the replacement batteries listed below. The unit may not 

operate properly with other batteries. Never use rechargeable batteries

since they may not provide a constant charge.
This unit has been designed to be as maintenance-free as possible, but there

are a few simple things you must do to keep it working properly:

Test it at least once a week.

Clean the Smoke Alarm at least once a month; gently vacuum the 

outside of the Smoke Alarm using your household vacuum’s soft brush

attachment. Test the Smoke Alarm. Never use water, cleaners or solvents

since they may damage the unit.

If the Smoke Alarm becomes contaminated by excessive dirt, dust and/or

grime, and cannot be cleaned to avoid unwanted alarms, replace the 

unit immediately.

Relocate the unit if it sounds frequent unwanted alarms. See “Locations 

To Avoid For Smoke Alarms” for details.

When the battery back-up becomes weak, the Smoke Alarm will “chirp”

about once a minute (the low battery warning). This warning should last 7

days, but you should replace the batteries immediately to continue your

protection.

UNDERSTANDING THE INDICATOR LIGHTS 
AND ALARM HORN PATTERNS

NOTE: When power is applied, unit(s) may alarm momentarily.
*
When any Smoke Alarm in an interconnected series triggers an alarm, its

red LED will flash rapidly. The red LEDs will remain OFF on any remaining

alarms in the series. This feature helps responders identify which unit(s) 

triggered the alarm.

Latching Alarm

Red LED flashing 2 

seconds on, 

2 seconds off

Not available

AC Power 

DC Power

Normal Operation

Constant Green LED
No Audible Alarm

Flashing Green LED

once/minute
No Audible Alarm

Test Condition

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Silence Mode

Rapidly Flashing 

Red LED
Audible Alarm Off

Rapidly Flashing 

Red LED
Audible Alarm Off

Alarm Condition*

(Initiating Unit)

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Alarm Condition*

(Remote Units)

Constant Green LED
Audible Alarm

Green LED Off
Audible Alarm

IF THIS SMOKE ALARM SOUNDS

RESPONDING TO AN ALARM

During an alarm, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause.

• If the unit alarms and you are not testing the unit, it is warning you of a

potentially dangerous situation that requires your immediate attention.

NEVER ignore any alarm. Ignoring the alarm may result in injury or

death.

• Never disconnect the AC power to quiet an unwanted alarm.

Disconnecting the power disables the Alarm so it cannot sense

smoke. This will remove your protection. Instead, open a window or

fan the smoke away from the unit. The Alarm will reset automatically.

• If the unit alarms get everyone out of the house immediately.

• ELECTRICAL SHOCK HAZARD: Attempting to disconnect the power

connector from the unit when the power is on may result in electrical

shock, serious injury or death.

When an interconnected system of AC powered units is in alarm, the alarm

indicator light on the unit(s) that initiated the alarm will blink rapidly. It will

remain OFF on any remaining units.
If the unit alarms, get everyone out of the dwelling immediately.
If the unit alarms and you are certain that the source of smoke is not a fire—

cooking smoke or an extremely dusty furnace, for example—open a nearby 

window or door and fan the smoke away from the unit (Use the Silence Feature

to silence the Alarm). This will silence the alarm, and once the smoke clears the

unit will reset itself automatically.

WHAT TO DO IN CASE OF FIRE

Don’t panic; stay calm. Follow your family escape plan.

Get out of the house as quickly as possible. Don’t stop to 

get dressed or collect anything.

Feel doors with the back of your hand before opening them. 

If a door is cool, open it slowly. Don’t open a hot door. Keep doors 

and windows closed, unless you must escape through them.

Cover your nose and mouth with a cloth (preferably damp). 

Take short, shallow breaths.

Meet at your planned meeting place outside your home, 

and do a head count to make sure everybody got out safely.

Call the Fire Department as soon as possible from outside. 

Give your address, then your name.

Never go back inside a burning building for any reason.

Contact your Fire Department for ideas on making your home safer.

Alarms have various limitations. See "Limitations of Smoke Alarms" for

details.

IF YOU SUSPECT A PROBLEM

Smoke Alarms may not operate properly because of dead, missing or weak

batteries, a build-up of dirt, dust or grease on the Smoke Alarm cover, or

installation in an improper location. Clean the Smoke Alarm as described in

“Regular Maintenance,” and install fresh batteries, then test the Smoke Alarm

again. If it fails to test properly when you use the test button, or if the problem

persists, replace the Smoke Alarm immediately.

If you hear a “chirp” approximately once a minute, replace the 

batteries.

If you experience frequent non-emergency alarms (like those caused

by cooking smoke), try relocating the Smoke Alarm.

If the alarm sounds when no smoke is visible, try cleaning or 

relocating the Smoke Alarm. The cover may be dirty.

If the alarm does not sound during testing, make sure it is receiving

AC power from the household current.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the test button for 5-10 seconds to discharge the

branch circuit.

If the Smoke Alarm is still not operating properly, and it is still under warranty,

please see “How to Obtain Warranty Service” in the Limited Warranty.

Do not try fixing the alarm yourself – this will void your warranty!

LIMITED WARRANTY

BRK Brands, Inc., ("BRK") the maker of First Alert

®

brand and BRK

®

brand

products, warrants that for a period of ten years from the date of purchase,

this product will be free from defects in material and workmanship. 

BRK, at its option, will repair or replace this product or any component of

the product found to be defective during the warranty period. Replacement

will be made with a new or remanufactured product or component. If the

product is no longer available, replacement may be made with a similar

product of equal or greater value. This is your exclusive warranty.
This warranty is valid for the original retail purchaser from the date of initial

retail purchase and is not transferable. Keep the original sales receipt. 

Proof of purchase is required to obtain warranty performance. 

BRK dealers, service centers, or retail stores selling BRK products do not

have the right to alter, modify or any way change the terms and conditions

of this warranty.
This warranty does not cover normal wear of parts or damage resulting

from any of the following: negligent use or misuse of the product, use on

improper voltage or current, use contrary to the operating instructions, 

disassembly, repair or alteration by anyone other than BRK or an authorized

service center. Further, the warranty does not cover Acts of God, such as

fire, flood, hurricanes and tornadoes or any batteries that are included with

this unit.
BRK shall not be liable for any incidental or consequential damages

caused by the breach of any express or implied warranty. Except to the

extent prohibited by applicable law, any implied warranty of merchantability

or fitness for a particular purpose is limited in duration to the duration of

the above warranty. Some states, provinces or jurisdictions do not allow

the exclusion or limitation of incidental or consequential damages or 

limitations on how long an implied warranty lasts, so the above limitations

or exclusion may not apply to you. This warranty gives you specific legal

rights, and you may also have other rights that vary from state to state or

province to province.
How to Obtain Warranty Service
Service: 
If service is required, do not return the product to your retailer. 

In order to obtain warranty service, contact the Consumer Affairs Division

at 1-800-323-9005, 7:30 AM - 5:00 PM Central Standard Time, Monday

through Friday. To assist us in serving you, please have the model number

and date of purchase available when calling.  

For Warranty Service return to:

BRK Brands, Inc., 25 Spur Drive, El Paso, TX 79906
Battery: BRK Brands, Inc. make no warranty, express or implied, written or

oral, including that of merchantability or fitness for any particular purpose

with respect to battery.

RECOMMENDED LOCATIONS FOR 

SMOKE ALARMS

Installing Smoke Alarms in Single-Family Residences
The National Fire Protection Association (NFPA), recommends one Smoke

Alarm on every floor, in every sleeping area, and in every bedroom. In new

construction, the Smoke Alarms must be AC powered and interconnected.

See “Agency Placement Recommendations” for details. For additional cover-

age, it is recommended that you install a Smoke Alarm in all rooms, halls,

storage areas, finished attics, and basements, where temperatures normally

remain between 40˚ F (4.4˚ C) and 100˚ F (37.8˚ C). Make sure no door or

other obstruction could keep smoke from reaching the Smoke Alarms.
More specifically, install Smoke Alarms:

On every level of your home, including finished attics and basements.

Inside every bedroom, especially if people sleep with the door partly or

completely closed.

In the hall near every sleeping area. If your home has multiple sleeping

areas, install a unit in each. If a hall is more than 40 feet long (12 meters),

install a unit at each end.

At the top of the first-to-second floor stairway, and at the bottom 

of the basement stairway.

Specific requirements for Smoke Alarm installation vary from state to state

and from region to region. Check with your local Fire Department for current

requirements in your area. 

It is recommended AC or AC/DC units be inter-

connected for added protection.

INSTALLING SMOKE ALARMS IN MOBILE HOMES & RVS

For minimum security install one Smoke Alarm as close to each sleeping area

as possible. For more security, put one unit in each room. Many older mobile

homes (especially those built before 1978) have little or no insulation. If your

mobile home is not well insulated, or if you are unsure of the amount of 

insulation, it is important to install units on inside walls only. Smoke Alarms

should be installed where temperatures normally remain between 40˚ F (4.4˚ C)

and 100˚ F (37.8˚ C). 

WARNING: Test units used in RVs after the vehicle has been in storage,

before every trip, and once a week while in use. Failure to test units

used in RVs as described may remove your protection.

LIMITATIONS OF SMOKE ALARMS

Smoke Alarms have played a key role in reducing deaths resulting from home

fires worldwide. However, like any warning device, Smoke Alarms can only

work if they are properly located, installed, and maintained, and if smoke

reaches the Alarms. They are not foolproof.
Smoke alarms may not waken all individuals. Practice the escape plan 

at least twice a year, making sure that everyone is involved – from kids to

grandparents. Allow children to master fire escape planning and practice

before holding a fire drill at night when they are sleeping. If children or others

do not readily waken to the sound of the smoke alarm, or if there are infants

or family members with mobility limitations, make sure that someone is

assigned to assist them in fire drill and in the event of an emergency. It is 

recommended that you hold a fire drill while family members are sleeping in

order to determine their response to the sound of the smoke alarm while

sleeping and to determine whether they may need assistance in the event 

of an emergency.
Smoke Alarms cannot work without power. Battery operated units cannot

work if the batteries are missing, disconnected or dead, if the wrong type 

of batteries are used, or if the batteries are not installed correctly. AC units 

cannot work if the AC power is cut off for any reason (open fuse or circuit

breaker, failure along a power line or at a power station, electrical fire that

burns the electrical wires, etc.). If you are concerned about the limitations 

of battery or AC power, install both types of units.
Smoke Alarms cannot detect fires if the smoke does not reach the

Alarms. Smoke from fires in chimneys or walls, on roofs, or on the other side

of closed doors may not reach the sensing chamber and set off the Alarm.

That is why one unit should be installed inside each bedroom or sleeping

area—especially if bedroom or sleeping area doors are closed at night—and

in the hallway between them.
Smoke Alarms may not detect fire on another floor or area of the

dwelling. For example, a stand-alone unit on the second floor may not detect

smoke from a basement fire until the fire spreads. This may not give you

enough time to escape safely. That is why recommended minimum protection

is at least one unit in every sleeping area, and every bedroom on every level

of your dwelling. Even with a unit on every floor, stand-alone units may not

provide as much protection as interconnected units, especially if the fire starts

in a remote area. Some safety experts recommend installing interconnected

AC powered units with battery back-up (see “About Smoke Alarms”) or 

professional fire detection systems, so if one unit senses smoke, all units

alarm. Interconnected units may provide earlier warning than stand-alone 

units since all units alarm when one detects smoke.
Smoke Alarms may not be heard. Though the alarm horn in this unit meets

or exceeds current standards, it may not be heard if: 1) the unit is located 

outside a closed or partially closed door, 2) residents recently consumed

alcohol or drugs, 3) the Alarm is drowned out by noise from stereo, TV, traffic,

air conditioner or other appliances, 4) residents are hearing impaired or sound

sleepers. Special purpose units, like those with visual and audible alarms,

should be installed for hearing impaired residents.
Smoke Alarms may not have time to alarm before the fire itself causes

damage, injury, or death, since smoke from some fires may not reach 

the unit immediately. Examples of this include persons smoking in bed, 

children playing with matches, or fires caused by violent explosions

resulting from escaping gas.
Smoke Alarms are not foolproof. 
Like any electronic device, Smoke Alarms

are made of components that can wear out or fail at any time. You must test

the unit weekly to ensure your continued protection. Smoke Alarms cannot

prevent or extinguish fires. They are not a substitute for property or life 

insurance.
Smoke Alarms have a limited life. The unit should be replaced immediately 

if it is not operating properly. You should always replace a Smoke Alarm after

10 years from date of purchase. Write the purchase date on the space provided

on back of unit.

USING THE SILENCE FEATURE 

The Silence Feature can temporarily quiet an unwanted alarm for up to 15 

minutes.

The Silence Feature does not disable the unit—it makes it temporarily

less sensitive to smoke. For your safety, if smoke around the unit is dense

enough to suggest a potentially dangerous situation, the unit will stay in

alarm or may re-alarm quickly. If you do not know the source of the

smoke, do not assume it is an unwanted alarm. Not responding to an

alarm can result in property loss, injury, or death.
To silence Smoke Alarms in an interconnected series:
1. To silence multiple alarms in an interconnected series, you must press the

Test/Silence button on the unit(s) that triggered the alarm.

2. Once you activate the Silence feature, the Red LED will flash approximately

once every 10 seconds.

3. Pressing the Test/Silence button when in silence will restart the silence

timer.

The Silence Feature on these units can temporarily quiet an unwanted alarm for

up to 15 minutes. To use this feature, press the Test/Silence button on the cover.

If the unit will not silence and no heavy smoke is present, or if it stays in

silence mode continuously, it should be replaced immediately.

Model 3120B

with Battery Back-Up and Silence

AC Powered 

Photo & Ion Smoke Alarm

Input: 120V AC 

~

, 60Hz, 0.07A

Make sure the Alarm is not receiving excessively noisy power. Examples of noisy power could be major appliances on the same circuit, power from a

generator or solar power, light dimmer on the same circuit or mounted near fluorescent lighting. Excessively noisy power may cause damage to your

Alarm.

Low Battery

Alarm “chirp’’ approx.

once/minute

Alarm “chirp’’ approx.

once/minute

Low Battery Latch

Green LED flashing 2

seconds on, 

2 seconds off

Not available

LISTED TO

UL 217 

STANDARD

AGENCY PLACEMENT RECOMMENDATIONS

NFPA 72 (National Fire Code) Chapter 11
“For your information, the National Fire Protection Association's Standard 72,

reads as follows:”
“11.5.1 One- and Two-Family Dwelling Units.”
“11.5.1.1 Smoke Detection. 
Where required by applicable laws, codes, or 

standards for the specified occupancy, approved single- and multiple-station

Smoke Alarms shall be installed as follows: (1) In all sleeping rooms.

Exception: Smoke Alarms shall not be required in sleeping rooms in existing

one- and two-family dwelling units. (2) Outside of each separate sleeping area,

in immediate vicinity of the sleeping rooms. (3) On each level of the dwelling

unit, including basements. Exception: In existing one- and two family dwelling

units, approved Smoke Alarms powered by batteries are permitted.”
“A.11.8.3 Are More Smoke Alarms Desirable? The required number of

Smoke Alarms might not provide reliable early warning protection for those

areas separated by a door from the areas protected by the required Smoke

Alarms. For this reason, it is recommended that the householder consider 

the use of additional Smoke Alarms for those areas for increased protection.

The additional areas include the basement, bedrooms, dining room, furnace

room, utility room, and hallways not protected by the required Smoke Alarms.

The installation of Smoke Alarms in kitchens, unfinished attics, or garages 

is not normally recommended, as these locations occasionally experience

conditions that can result in improper operation.”

California State Fire Marshal (CSFM)

Early warning detection is best achieved by the installation of fire detection

equipment in all rooms and areas of the household as follows: A Smoke Alarm

installed in each separate sleeping area (in the vicinity, but outside bedrooms),

and Heat or Smoke Alarms in the living rooms, dining rooms, bedrooms,

kitchens, hallways, finished attics, furnace rooms, closets, utility and storage

rooms, basements, and attached garages.

LOCATIONS TO AVOID FOR SMOKE ALARMS

For best performance, AVOID installing Smoke Alarms in these areas:

Where combustion particles are produced. Combustion particles form

when something burns. Areas to avoid include poorly ventilated kitchens,

garages, and furnace rooms. Keep units at least 20 feet (6 meters) from

the sources of combustion particles (stove, furnace, water heater, space

heater) if possible. In areas where a 20-foot distance is not possible – in

modular, mobile, or smaller homes, for example – it is recommended 

the Smoke Alarm be placed as far from these fuel-burning sources as 

possible. The placement recommendations are intended to keep these

Alarms at a reasonable distance from a fuel-burning source, and thus

reduce “unwanted” alarms. Unwanted alarms can occur if a Smoke

Alarm is placed directly next to a fuel-burning source. Ventilate these

areas as much as possible.

In air streams near kitchens. Air currents can draw cooking smoke into

the sensing chamber of a Smoke Alarm near the kitchen.

In very damp, humid or steamy areas, or directly near bathrooms with

showers. Keep units at least 10 feet (3 meters) away from showers,

saunas, dishwashers, etc.

Where the temperatures are regularly below 40˚ F (4.4˚ C) or above 

100˚ F (37.8˚ C) including unheated buildings, outdoor rooms, porches, 

or unfinished attics or basements.

In very dusty, dirty, or greasy areas. Do not install a Smoke Alarm directly

over the stove or range. Clean a laundry room unit frequently to keep it

free of dust or lint.

Near fresh air vents, ceiling fans, or in very drafty areas. Drafts can blow

smoke away from the unit, preventing it from reaching sensing chamber.

In insect infested areas. Insects can clog openings to the sensing chamber

and cause unwanted alarms.

Less than 12 inches (305 mm) away from fluorescent lights. Electrical

“noise” can interfere with the sensor.

In “dead air” spaces. “Dead air” spaces may prevent smoke from reaching

the Smoke Alarm.

AVOIDING DEAD AIR SPACES

“Dead air” spaces may prevent smoke from reaching the Smoke Alarm. To

avoid dead air spaces, follow the installation recommendations below.
On ceilings, install Smoke Alarms as close to the center of the ceiling as 

possible. If this is not possible, install the Smoke Alarm at least 4 inches 

(102 mm) from the wall or corner.
For wall mounting (if allowed by building codes), the top edge of Smoke

Alarms should be placed between 4 inches (102 mm) and 12 inches (305 mm)

from the wall/ceiling line, below typical “dead air” spaces.
On a peaked, gabled, or cathedral ceiling, install the first Smoke Alarm 

within 3 feet (0.9 meters) of the peak of the ceiling, measured horizontally.

Additional Smoke Alarms may be required depending on the length, angle,

etc. of the ceiling's slope. Refer to NFPA 72 for details on requirements for

sloped or peaked ceilings.

SPECIAL COMPLIANCE CONSIDERATIONS

This Smoke Alarm alone is not a suitable substitute for complete fire

detection systems in places housing many people—like apartment 

buildings, condominiums, hotels, motels, dormitories, hospitals, long-

term health care facilities, nursing homes, day care facilities, or group

homes of any kind—even if they were once single-family homes. It is not

a suitable substitute for complete fire detection systems in warehouses,

industrial facilities, commercial buildings, and special-purpose non-resi-

dential buildings which require special fire detection and alarm systems.

Depending on the building codes in your area, this Smoke Alarm may be

used to provide additional protection in these facilities.
The following information applies to all four types of buildings listed below: 
In new construction, most building codes require the use of AC or AC/DC 

powered Smoke Alarms only. AC, AC/DC, or DC powered Smoke Alarms can be

used in existing construction as specified by local building codes. Refer to NFPA

72 (National Fire Alarm Code) and NFPA 101 (Life Safety Code), local building

codes, or consult your Fire Department for detailed fire protection requirements

in buildings not defined as “households.”
1. Single-Family Residence: 

Single family home, townhouse. It is recommended Smoke Alarms be installed

on every level of the home, in every bedroom, and in each bedroom hallway.
2. Multi-Family or Mixed Occupant Residence: 

Apartment building, condominium. This Smoke Alarm is suitable for use in

individual apartments or condos, provided a primary fire detection system

already exists to meet fire detection requirements in common areas like 

lobbies, hallways, or porches. Using this Smoke Alarm in common areas may

not provide sufficient warning to all residents or meet local fire protection 

ordinances/regulations.
3. Institutions: 

Hospitals, day care facilities, long-term health care facilities. This Smoke 

Alarm is suitable for use in individual patient sleeping/resident rooms, 

provided a primary fire detection system already exists to meet fire detection

requirements in common areas like lobbies, hallways, or porches. Using this

Smoke Alarm in common areas may not provide sufficient warning to all 

residents or meet local fire protection ordinances/regulations.
4. Hotels and Motels: 

Also boarding houses and dormitories. This Smoke Alarm is suitable for use

inside individual sleeping/resident rooms, provided a primary fire detection 

system already exists to meet fire detection requirements in common areas 

like lobbies, hallways, or porches. Using this Smoke Alarm in common areas

may not provide sufficient warning to all residents or meet local fire protection

ordinances/regulations.

ABOUT SMOKE ALARMS

Battery (DC) operated Smoke Alarms: Provide protection even when 

electricity fails, provided the batteries are fresh and correctly installed. Units

are easy to install, and do not require professional installation. They do not,

however, provide interconnected functionality.
AC powered Smoke Alarms: Can be interconnected so if one unit senses

smoke, all units alarm. They do not operate if electricity fails. 

AC with battery (DC) back-up: will operate if electricity fails, provided the

batteries are fresh and correctly installed. AC and AC/DC units must be

installed by a qualified electrician.
Wireless Interconnected Alarms: Offer the same interconnected functionality

as with hardwired alarms, without wires. Units are easy to install and do not

require professional installation. They provide protection even when electricity

fails, provided the batteries are fresh and correctly installed.
Smoke Alarms for Solar or Wind Energy users and battery backup power

systems: AC powered Smoke Alarms should only be operated with true or

pure sine wave inverters. Operating this Smoke Alarm with most battery-

powered UPS (uninterruptible power supply) products or square wave or

“quasi sine wave” inverters 

will damage the Alarm. If you are not sure about

your inverter or UPS type, please consult with the manufacturer to verify.
Smoke Alarms for the hearing impaired: Special purpose Smoke Alarms

should be installed for the hearing impaired. They include a visual alarm and

an audible alarm horn, and meet the requirements of the Americans With

Disabilities Act. These units can be interconnected so if one unit senses

smoke, all units alarm.

Continued...

ABOUT SMOKE ALARMS, Continued
Smoke alarms are not to be used with detector guards unless the 

combination has been evaluated and found suitable for that purpose.
All these Smoke Alarms are designed to provide early warning of fires if 

located, installed and cared for as described in the user’s manual, and if

smoke reaches the Alarm. If you are unsure which type of unit to install, refer

to NFPA (National Fire Protection Association) 72 (National Fire Alarm Code)

and NFPA 101 (Life Safety Code). National Fire Protection Association, One

Batterymarch Park, Quincy, MA 02269-9101. Local building codes may also

require specific units in new construction or in different areas of the home.

2

1

Choosing a replacement battery:
Your Smoke/CO Alarm requires two “AA” Energizer E91 batteries. 

These batteries are available at many local retail stores.

Actual battery service life depends on the Alarm and the environment in which

it is installed. All the batteries specified above are acceptable replacement

batteries for this unit. Regardless of the manufacturer’s suggested battery life,

you MUST replace the battery immediately once the unit starts “chirping”

(the “low battery warning”).
To replace the batteries (without removing Alarm from the ceiling or wall):
1. Open the battery compartment.
2. Press tabs A and B as shown in the diagram

and remove each battery.

3. Insert the new batteries, making sure 

they snap completely into the battery 

compartment. Match the terminals on the

ends of the batteries with the terminals on

the unit.

4. Close the battery compartment, and then

test the unit by pressing the Test/Silence 

button.

AB

SILENCING THE LOW BATTERY WARNING

This Silence Feature can temporarily quiet the low battery warning “chirp” for

up to 8 hours. Press the Test/Silence button on the Alarm cover until you hear

the acknowledge “chirp”.
Once the low battery warning “chirp” silence feature is activated, the unit

continues to flash the green light once a minute for approximately 8 hours.

After 8 hours, the low battery “chirp” will resume. The Alarm will continue 

to operate as long as AC power is supplied. However, 

replace the batteries

as soon as possible, to maintain protection in event of a power outage.
To silence Alarms in an interconnected series:

To silence an interconnected series of Smoke/CO Alarms, you must press the

Test/Silence button on the initiating alarm (The unit with the flashing red light;

the red light will be off on all other Alarms.). If you press the Test/Silence on

any other Alarm, it will only silence that unit, not the whole interconnected

series.

LATCHING FEATURE

Alarm Latch is activated after an Alarm is exposed to alarm levels of smoke.

This feature will only work with AC power. After smoke levels drop below alarm

levels, the

Red LED will begin flashing 2 seconds on, 2 seconds off unless

reset by test/silence button.
This feature helps emergency responders, investigators, or service 

technicians identify which unit(s) in your home were exposed to alarm levels

of smoke. This can help investigators pinpoint the source of smoke.
Interconnected Alarms. Latching Alarm Indicator shows which Alarm(s) in the

series were exposed to alarm levels of smoke. The Latching Alarm Indicator

stays ON until you clear it, so it can alert you to an alarm that occurred while

you were away from home, even though smoke present in the air has dropped

below alarm levels.
Low Battery Latch is activated when the Alarm is in the "low battery 

condition". When this occurs, the 

Green LED flashes 2 seconds on, 2 

seconds off. This feature is designed to help you identify which Alarm needs

to have the battery replaced. Although, the Alarm will sound the low battery

chirp approximately once every minute, sometimes during the initial stages 

of "low battery", the Alarm will chirp in greater intervals than one minute,

sometimes up to several hours, until the battery reaches a steady low battery

level. This innovative feature eliminates the frustration of waiting for and/or

identifying which unit is chirping.

“SMART INTERCONNECT” FEATURE

This Alarm includes "Smart Interconnect" which enables the Alarm to be

interconnected with other First Alert

®

and BRK Smoke, Heat, and "Smart

Interconnect" Smoke, Smoke/CO and CO Alarms. When smoke is detected,

all Alarms will sound the smoke horn pattern. When CO is detected, "Smart

Interconnect" Alarms will sound the CO horn pattern. Alarms that do not have

the "Smart Interconnect" feature will remain silent during a CO alarm.

Model 3120B

Printed in Mexico

M08-0224-000   

11/10

IMPORTANT! PLEASE READ CAREFULLY AND SAVE.

This user’s manual contains important information about your Smoke

Alarm’s operation. If you are installing this Smoke Alarm for use by 

others, you must leave this manual—or a copy of it—with the end user.

INTRODUCTION

Thank you for choosing First Alert

®

for your Smoke Alarm needs. You have 

purchased a state of the art Smoke Alarm designed to provide you with an

early warning of a fire. Please take the time to read this manual and make

this Smoke Alarm an integral part of your family’s safety plan.

Key Features of the 3120B Photo & Ion Combo Smoke Alarm:
Photo & Ion Smoke Sensors: 
Dual photoelectric and ionization smoke 

sensing technologies for optimal sensing of smoke particles produced in

both flaming and smoldering fires.
Optipath 360 Technology

TM

Patented technology provides 360˚ of direct

access to the smoke sensor.
Two Silence Features: Low Battery Silence temporarily silences low 

battery chirp for up to eight hours before replacing low battery. 

Alarm Silence silences an unwanted alarm for several minutes.
Two Latching Features: Alarm Latch remembers which unit initiated an

alarm. 

Low Battery Latch visually identifies which unit is in low battery 

condition.
Perfect Mount: Mounting bracket keeps alarm secure over a wide rotation

range to allow for perfect alignment.
Battery back-up: Keeps alarm functioning during a power interruption 

provided batteries are fresh and installed properly.
© 2010 BRK Brands, Inc. All rights reserved. Distributed by BRK Brands, Inc.

3901 Liberty Street Road, Aurora, IL 60504-8122

Consumer Affairs: (800) 323-9005

www.firstalert.com   •   www.brkelectronics.com

FIRE SAFETY TIPS

Follow safety rules and prevent hazardous situations: 1) Use smoking 

materials properly. Never smoke in bed. 2) Keep matches or lighters away 

from children; 3) Store flammable materials in proper containers; 

4) Keep electrical appliances in good condition and don’t overload electrical

circuits; 5) Keep stoves, barbecue grills, fireplaces and chimneys grease- 

and debris-free; 6) Never leave anything cooking on the stove unattended; 

7) Keep portable heaters and open flames, like candles, away from flammable

materials; 8) Don’t let rubbish accumulate.
Keep alarms clean, and test them weekly. Replace alarms immediately if they

are not working properly. Smoke Alarms that do not work cannot alert you to a

fire. Keep at least one working fire extinguisher on every floor, and an additional

one in the kitchen. Have fire escape ladders or other reliable means of escape

from an upper floor in case stairs are blocked.

BEFORE YOU INSTALL THIS SMOKE ALARM

IMPORTANT! Read “Recommended Locations for Smoke Alarms” and

“Locations to Avoid for Smoke Alarms” before beginning. This unit monitors

the air, and when smoke reaches its sensing chamber, it alarms. It can give

you more time to escape before fire spreads. This unit can ONLY give an early

warning of developing fires if it is installed, maintained and located where

smoke can reach it, and where all residents can hear it, as described in this

manual. This unit will not sense gas, heat, or flame. It cannot prevent or 

extinguish fires.
Understand The Different Type of Smoke Alarms

Battery powered or electrical? Different Smoke Alarms provide different

types of protection. See “About Smoke Alarms” for details.

Know Where To Install Your Smoke Alarms

Fire Safety Professionals recommend at least one Smoke Alarm on every

level of your home, in every bedroom, and in every bedroom hallway or

separate sleeping area. See “Recommended Locations For Smoke Alarms”

and “Locations To Avoid For Smoke Alarms” for details.

Know What Smoke Alarms Can and Can’t Do

A Smoke Alarm can help alert you to fire, giving you precious time to

escape. It can only sound an alarm once smoke reaches the sensor. 

See “Limitations of Smoke Alarms” for details.

Check Your Local Building Codes

This Smoke Alarm is designed to be used in a typical single-family home. 

It alone will not meet requirements for boarding houses, apartment 

buildings, hotels or motels. See “Special Compliance Considerations” 

for details.

5

6

7

1

2

3

All First Alert

®

and BRK

®

Smoke Alarms conform to regulatory 

requirements, including UL217 and are designed to detect particles of

combustion. Smoke particles of varying number and size are produced

in all fires.

Ionization technology is generally more sensitive than photoelectric

technology at detecting small particles, which tend to be produced

in greater amounts by flaming fires, which consume combustible

materials rapidly and spread quickly. Sources of these fires may include

paper burning in a wastebasket, or a grease fire in the kitchen.

Photoelectric technology is generally more sensitive than ionization

technology at detecting large particles, which tend to be produced in

greater amounts by smoldering fires, which may smolder for hours

before bursting into flame. Sources of these fires may include cigarettes

burning in couches or bedding.
For maximum protection, use both types of Smoke Alarms on each

level and in every bedroom of your home.

USER’S MANUAL

SMOKE ALARMS

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

• This unit will not alert hearing impaired residents. It is recom-

mended that you install special units which use devices like

flashing strobe lights to alert hearing impaired residents.

• Installation of this unit must conform to the electrical codes in 

your area; Articles 210 and 300.3 (B) of NFPA 70 (NEC), NFPA 72,

NFPA 101; SBC (SBCCI); UBC (ICBO); NBC (BOCA); OTFDC (CABO),

and any other local or building codes that may apply. Wiring and

installation must be performed by a licensed electrician. Failure to

follow these guidelines may result in injury or property damage.

• This unit must be powered by a 24-hour, 120VAC pure sine wave

60Hz circuit. Be sure the circuit cannot be turned off by a switch,

dimmer, or ground fault circuit interrupter. Failure to connect this

unit to a 24-hour circuit may prevent it from providing constant

protection.

• This Smoke Alarm must have AC or battery power to operate.

If the AC power fails, battery back-up will allow the alarm to

sound for at least 4 minutes. If AC power fails and the battery is

weak, protection should last for at least 7 days. If AC power fails

and the battery is dead or missing, the alarm cannot operate.

• Never disconnect the power from an AC powered unit to stop an

unwanted alarm. Doing so will disable the unit and remove your

protection. In the case of a true unwanted alarm open a window

or fan the smoke away from the unit. The alarm will reset auto-

matically when it returns to normal operation. Never remove the

batteries from a battery operated unit to stop an unwanted alarm

(caused by cooking smoke, etc.). Instead open a window or fan

the smoke away from the unit. The alarm will reset automatically.

• Connect this unit ONLY to other compatible units. See “How To

Install This Smoke Alarm” for details. Do not connect it to any

other type of alarm or auxiliary device. Connecting anything else

to this unit may damage it or prevent it from operating properly.

• This Smoke Alarm has a battery drawer which resists closing

unless a battery is installed. This warns you the unit will not

operate under DC power without a battery.

• Do not stand too close to the unit when the alarm is sounding. 

It is loud to wake you in an emergency. Exposure to the horn at

close range may harm your hearing.

• Do not paint over the unit. Paint may clog the openings to the

sensing chambers and prevent the unit from operating properly.

The Mounting Bracket:

To remove the mounting bracket from the Smoke

Alarm base, hold the Smoke Alarm base firmly 

and twist the mounting bracket counterclockwise.

The mounting bracket installs onto the junction box.

It has a variety of screw slots to fit most boxes.

The Power Connector: 

The power connector plugs into a power input block on

the Smoke Alarm. It supplies the unit with AC power.

• The black wire is “hot.” 
• The white wire is neutral.
• The orange wire is used for interconnect.

If you need to remove the power connector, turn 

POWER OFF first. Insert a flat screwdriver blade

between the power connector and the security tab

inside the power input block. Gently pry back the tab

and pull the connector free.

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The Parts of This Unit
1

Mounting Bracket

2

Mounting Slots

3

Locking Pins (break out of bracket)

4

Hot (Black) AC Wire

5

Neutral (White) AC Wire

6

Interconnect (Orange) Wire

7

Quick-Connect Power Connector

8

Turn this way to remove from bracket

9

Turn this way to attach to bracket

10 Slide-Out Battery Drawer

The basic installation of this Smoke Alarm is similar whether you want to

install one Smoke Alarm, or interconnect more than one Smoke Alarm. 

If you are interconnecting more than one Smoke Alarm, you MUST read

“Special Requirements For Interconnected Smoke Alarms” below before

you begin installation.

ELECTRICAL SHOCK HAZARD. Turn off power to the area where you 

will install this unit at the circuit breaker or fuse box before beginning

installation. Failure to turn off the power before installation may result 

in serious electrical shock, injury or death.
1. Remove the mounting bracket from the base, and attach it to the 

junction box.
Activate the battery back-up by removing the “Pull to Activate Battery

Back-Up” tab. Or, install battery back-up. Battery back-up cannot work

until you install the battery in the correct position (Match “+” to “+” and

“-” to “-”).
Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

2. Using wire nuts, connect the power connector to the household wiring.

3. Plug the power connector into the back of the Smoke Alarm.
4. Position the base of the Smoke Alarm over the mounting bracket and

turn. The Alarm can be positioned over the bracket every 90°.

Turn the Smoke Alarm clockwise (right) until the unit is in place.

5. Check all connections.

Improper wiring of the power connector or the wiring leading to the

power connector will cause damage to the Alarm and may lead to a

non-functioning Alarm.

ELECTRICAL SHOCK HAZARD. Do not restore power until all Smoke

Alarms are completely installed. Restoring power before installation is

complete may result in serious electrical shock, injury or death.
6. Make sure the Smoke Alarm is receiving AC power. Under normal 

operation, the Green power indicator light will shine continuously. 

7. If the Green power indicator light does not light, 

TURN OFF POWER 

TO THE JUNCTION BOX and recheck all connections. If all connections

are correct and the Green power indicator still does not light when you

restore the power, the unit should be replaced immediately.

8. Test each Smoke Alarm. Press and hold the Test/Silence button until the

unit alarms. 

When testing a series of interconnected units you must

test each unit individually. Make sure all units alarm when each one

is tested.

Continued...

8. Continued

If any unit in the series does not alarm, 

TURN OFF POWER and recheck

connections. If it does not alarm when you restore power, replace it 

immediately.

Special Requirements For Interconnected Smoke Alarms

• Failure to meet any of the above requirements could damage the

units and cause them to malfunction, removing your protection.

• AC and AC/DC Smoke Alarms can be interconnected. Under AC

power, all units will alarm when one senses smoke. When power 

is interrupted, only the AC/DC units in the series will continue to

send and receive signals. AC powered Smoke Alarms will not

operate.

Interconnected units can provide earlier warning of fire than stand-alone units,

especially if a fire starts in a remote area of the dwelling. If any unit in the series

senses smoke, all units will alarm. To determine which Smoke Alarm initiated an

alarm, see table:

During an Alarm:
On Initiating Alarm(s)

Red LED(s) flashes (flash) rapidly

On All Other Alarms

Red LED is Off

After an Alarm (Latching):
On Initiating Alarm(s)

Red LED(s) flash 3 times, spaced one second apart. 

The pattern repeats approximately every 45 seconds.

On All Other Alarms

Green LED(s) On, Red LED(s) Off

Interconnect units within a single family residence only. Otherwise all 

households will experience unwanted alarms when you test any unit in the

series. Interconnected units will only work if they are wired to compatible

units and all requirements are met. This unit is designed to be compatible

with: 

First Alert

®

Smoke Alarm Models SA4120, SA4121B, SA100B, SA520

and 

BRK

®

Smoke Alarm Models 3120B, 9120, 9120B, SC6120B, SC9120B,

7010, 7010B, 7010BSL, 7020B, SC7010B, SC7010BV, 100S, 4120, 4120B,

4120SB; 

BRK

®

CO Alarm Models CO5120BN, CO5120PDBN; BRK

®

Heat

Alarm Models HD6135F and HD6135FB; BRK

®

Auxiliary Devices Models

RM3 and RM4 (Relay Modules), SL177 (Strobe Light). 

See www.brkelectronics.com for most current interconnect list.

Interconnected units must meet ALL of the following requirements:

• A maximum of 18 compatible units may be interconnected 

(Maximum of 12 Smoke Alarms).

• The same fuse or circuit breaker must power all interconnected units.
• The total length of wire interconnecting the units should be less than

1000 feet (300 meters). This type of wire is commonly available at

Hardware and Electrical Supply stores.

• All wiring must conform to all local electrical codes and NFPA 70 (NEC).

Refer to NFPA 72, NFPA 101, and/or your local building code for further 

connection requirements.

HOW TO INSTALL THIS SMOKE ALARM

THE PARTS OF THIS SMOKE ALARM

This Smoke Alarm is designed to be mounted on any standard wiring junction box up to a 4-inch (10 cm) size, on either the ceiling or wall (if allowed by local codes).

Read “Recommended Locations For Smoke Alarms” and “Locations to Avoid For Smoke Alarms” before you begin installation. 

Tools you will need:  • Needle-nose pliers or utility knife • Standard Flathead screwdriver.

FOLLOW THESE INSTALLATION STEPS

STAND-ALONE ALARM ONLY:

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Tuck the orange wire inside the junction box. It is used for interconnect

only.

INTERCONNECTED UNITS ONLY:
Strip off about 1/2” (12 mm) of the plastic coating on the orange wire

on the power connector.

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Connect the orange wire on the power connector to the interconnect

wire in the junction box. Repeat for each unit you are interconnecting.

Never connect the hot or neutral wires in the junction box to the orange

interconnect wire. Never cross hot and neutral wires between Alarms.

STAND-ALONE ALARM ONLY:

If you are only installing one Smoke Alarm, restore power to the 

junction box.

INTERCONNECTED UNITS ONLY:

If you are interconnecting multiple Smoke Alarms, repeat steps 

1-5 for each Smoke Alarm in the series. When you are finished,

restore power to the junction box.

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A. Unswitched 120VAC 

60 Hz source

B. To additional units; Maximum = 18 total

(Maximum 12 Smoke Alarms)

1. Smoke Alarm
2. Ceiling or Wall
3. Power Connector

4. Wire Nut
5. Junction Box
6. Neutral Wire (Wht)

7. Interconnect Wire

(Orange)

8. Hot Wire (Blk) 

4

OPTIONAL LOCKING FEATURES

The locking features are designed to discourage unauthorized removal of the batteries or Alarm. It is not necessary to activate the locks in single-family 

households where unauthorized battery or Alarm removal is not a concern.
These Smoke Alarms have two separate locking features: one to lock the battery compartment, and the other to lock the Smoke Alarm 

to the mounting bracket. You can choose to use either feature independently, or use them both.
Tools you will need: • Needle-nose pliers or utility knife  • Standard Flathead screwdriver.
Both locking features use locking pins, which are molded into the mounting bracket. Using needle-nose pliers or a utility knife, remove

one or both pins from the mounting bracket, depending on how many locking features you want to use.

To permanently remove either lock, insert a flathead screwdriver between the locking pin and the lock, and pry the pin out of the lock.

TO LOCK THE BATTERY COMPARTMENT

Do not lock the battery compartment until you have installed the 

batteries and tested the battery back-up.
1. Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

If the unit does not alarm during testing, DO NOT lock the battery

compartment! Install new batteries and test again. If the Smoke 

Alarm still does not alarm, replace it immediately.

2. Using needle-nose pliers or a utility knife, detach one locking pin 

from the mounting bracket.

3. Push the locking pin through the hole near the battery drawer on the

back of the Smoke Alarm.

TO UNLOCK THE BATTERY COMPARTMENT

Once the Smoke Alarm is installed, you must disconnect it from the AC power

before unlocking the battery compartment.

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse box.

Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.
1. Remove the Smoke Alarm from the mounting

bracket. If the unit is locked to the bracket, see

the section “To Unlock the Mounting Bracket.”

2. Disconnect the power connector by gently prying

it away from the back of the Smoke Alarm.

3. Insert a flathead screwdriver under the head 

of the locking pin, and gently pry it out of the 

battery compartment lock. (If you plan to relock

the battery compartment, save the locking pin.)

4. To relock the battery compartment, close the 

battery door and reinsert locking pin in lock.

5. Reconnect the power connector to the back of the Smoke Alarm, reattach

the Smoke Alarm to the mounting bracket, and restore the power.

When replacing the batteries, always test the Smoke Alarm before relocking

the battery compartment.

TO UNLOCK THE MOUNTING BRACKET

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.

1. Insert a flathead screwdriver between the

mounting bracket pin and the mounting bracket.

2. Pry the Smoke Alarm away from the bracket by

turning both the screwdriver and the Smoke

Alarm counterclockwise (left) at the same time.

TO LOCK THE MOUNTING BRACKET

1. Using needle-nose pliers, detach one locking pin from mounting bracket.

2. Insert the locking pin into the lock located

opposite from the battery drawer as shown

in the diagram.

3. When you attach the Smoke Alarm to the mounting bracket, the locking

pin’s head will fit into a notch on the bracket.

Locking Features (Continued)

Printed in Mexico   M08-0224-000   

11/10

First Alert

®

is a registered trademark of the First Alert Trust.

BRK

®

is a registered trademark of BRK Brands, Inc.

WEEKLY TESTING

NEVER use an open flame of any kind to test this unit. You might

accidentally damage or set fire to the unit or to your home. The built-

in test switch accurately tests the unit’s operation as required by

Underwriters Laboratories, Inc. (UL).

If the Alarm ever fails to test properly, replace it immediately.

Products under warranty may be returned to the manufacturer 

for replacement. See “Limited Warranty” at the end of this manual.

DO NOT stand close to the Alarm when the horn is sounding. Exposure

at close range may be harmful to your hearing. When testing, step away

when horn starts sounding.
It is important to test this unit every week to make 

sure it is working properly. Using the test button is the

recommended way to test this Smoke Alarm.
Press and hold the Test/Silence button on the cover of the

unit until the alarm sounds (the unit may continue to alarm

for a few seconds after you release the button). If it does

not alarm, make sure the unit is receiving power and test 

it again. If it still does not alarm, replace it immediately.
During testing, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause. LED flashes once every second.
When testing a series of interconnected units you must test each unit 

individually. Make sure all units alarm when each one is tested.

REGULAR MAINTENANCE

Use only the replacement batteries listed below. The unit may not 

operate properly with other batteries. Never use rechargeable batteries

since they may not provide a constant charge.
This unit has been designed to be as maintenance-free as possible, but there

are a few simple things you must do to keep it working properly:

Test it at least once a week.

Clean the Smoke Alarm at least once a month; gently vacuum the 

outside of the Smoke Alarm using your household vacuum’s soft brush

attachment. Test the Smoke Alarm. Never use water, cleaners or solvents

since they may damage the unit.

If the Smoke Alarm becomes contaminated by excessive dirt, dust and/or

grime, and cannot be cleaned to avoid unwanted alarms, replace the 

unit immediately.

Relocate the unit if it sounds frequent unwanted alarms. See “Locations 

To Avoid For Smoke Alarms” for details.

When the battery back-up becomes weak, the Smoke Alarm will “chirp”

about once a minute (the low battery warning). This warning should last 7

days, but you should replace the batteries immediately to continue your

protection.

UNDERSTANDING THE INDICATOR LIGHTS 
AND ALARM HORN PATTERNS

NOTE: When power is applied, unit(s) may alarm momentarily.
*
When any Smoke Alarm in an interconnected series triggers an alarm, its

red LED will flash rapidly. The red LEDs will remain OFF on any remaining

alarms in the series. This feature helps responders identify which unit(s) 

triggered the alarm.

Latching Alarm

Red LED flashing 2 

seconds on, 

2 seconds off

Not available

AC Power 

DC Power

Normal Operation

Constant Green LED
No Audible Alarm

Flashing Green LED

once/minute
No Audible Alarm

Test Condition

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Silence Mode

Rapidly Flashing 

Red LED
Audible Alarm Off

Rapidly Flashing 

Red LED
Audible Alarm Off

Alarm Condition*

(Initiating Unit)

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Alarm Condition*

(Remote Units)

Constant Green LED
Audible Alarm

Green LED Off
Audible Alarm

IF THIS SMOKE ALARM SOUNDS

RESPONDING TO AN ALARM

During an alarm, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause.

• If the unit alarms and you are not testing the unit, it is warning you of a

potentially dangerous situation that requires your immediate attention.

NEVER ignore any alarm. Ignoring the alarm may result in injury or

death.

• Never disconnect the AC power to quiet an unwanted alarm.

Disconnecting the power disables the Alarm so it cannot sense

smoke. This will remove your protection. Instead, open a window or

fan the smoke away from the unit. The Alarm will reset automatically.

• If the unit alarms get everyone out of the house immediately.

• ELECTRICAL SHOCK HAZARD: Attempting to disconnect the power

connector from the unit when the power is on may result in electrical

shock, serious injury or death.

When an interconnected system of AC powered units is in alarm, the alarm

indicator light on the unit(s) that initiated the alarm will blink rapidly. It will

remain OFF on any remaining units.
If the unit alarms, get everyone out of the dwelling immediately.
If the unit alarms and you are certain that the source of smoke is not a fire—

cooking smoke or an extremely dusty furnace, for example—open a nearby 

window or door and fan the smoke away from the unit (Use the Silence Feature

to silence the Alarm). This will silence the alarm, and once the smoke clears the

unit will reset itself automatically.

WHAT TO DO IN CASE OF FIRE

Don’t panic; stay calm. Follow your family escape plan.

Get out of the house as quickly as possible. Don’t stop to 

get dressed or collect anything.

Feel doors with the back of your hand before opening them. 

If a door is cool, open it slowly. Don’t open a hot door. Keep doors 

and windows closed, unless you must escape through them.

Cover your nose and mouth with a cloth (preferably damp). 

Take short, shallow breaths.

Meet at your planned meeting place outside your home, 

and do a head count to make sure everybody got out safely.

Call the Fire Department as soon as possible from outside. 

Give your address, then your name.

Never go back inside a burning building for any reason.

Contact your Fire Department for ideas on making your home safer.

Alarms have various limitations. See "Limitations of Smoke Alarms" for

details.

IF YOU SUSPECT A PROBLEM

Smoke Alarms may not operate properly because of dead, missing or weak

batteries, a build-up of dirt, dust or grease on the Smoke Alarm cover, or

installation in an improper location. Clean the Smoke Alarm as described in

“Regular Maintenance,” and install fresh batteries, then test the Smoke Alarm

again. If it fails to test properly when you use the test button, or if the problem

persists, replace the Smoke Alarm immediately.

If you hear a “chirp” approximately once a minute, replace the 

batteries.

If you experience frequent non-emergency alarms (like those caused

by cooking smoke), try relocating the Smoke Alarm.

If the alarm sounds when no smoke is visible, try cleaning or 

relocating the Smoke Alarm. The cover may be dirty.

If the alarm does not sound during testing, make sure it is receiving

AC power from the household current.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the test button for 5-10 seconds to discharge the

branch circuit.

If the Smoke Alarm is still not operating properly, and it is still under warranty,

please see “How to Obtain Warranty Service” in the Limited Warranty.

Do not try fixing the alarm yourself – this will void your warranty!

LIMITED WARRANTY

BRK Brands, Inc., ("BRK") the maker of First Alert

®

brand and BRK

®

brand

products, warrants that for a period of ten years from the date of purchase,

this product will be free from defects in material and workmanship. 

BRK, at its option, will repair or replace this product or any component of

the product found to be defective during the warranty period. Replacement

will be made with a new or remanufactured product or component. If the

product is no longer available, replacement may be made with a similar

product of equal or greater value. This is your exclusive warranty.
This warranty is valid for the original retail purchaser from the date of initial

retail purchase and is not transferable. Keep the original sales receipt. 

Proof of purchase is required to obtain warranty performance. 

BRK dealers, service centers, or retail stores selling BRK products do not

have the right to alter, modify or any way change the terms and conditions

of this warranty.
This warranty does not cover normal wear of parts or damage resulting

from any of the following: negligent use or misuse of the product, use on

improper voltage or current, use contrary to the operating instructions, 

disassembly, repair or alteration by anyone other than BRK or an authorized

service center. Further, the warranty does not cover Acts of God, such as

fire, flood, hurricanes and tornadoes or any batteries that are included with

this unit.
BRK shall not be liable for any incidental or consequential damages

caused by the breach of any express or implied warranty. Except to the

extent prohibited by applicable law, any implied warranty of merchantability

or fitness for a particular purpose is limited in duration to the duration of

the above warranty. Some states, provinces or jurisdictions do not allow

the exclusion or limitation of incidental or consequential damages or 

limitations on how long an implied warranty lasts, so the above limitations

or exclusion may not apply to you. This warranty gives you specific legal

rights, and you may also have other rights that vary from state to state or

province to province.
How to Obtain Warranty Service
Service: 
If service is required, do not return the product to your retailer. 

In order to obtain warranty service, contact the Consumer Affairs Division

at 1-800-323-9005, 7:30 AM - 5:00 PM Central Standard Time, Monday

through Friday. To assist us in serving you, please have the model number

and date of purchase available when calling.  

For Warranty Service return to:

BRK Brands, Inc., 25 Spur Drive, El Paso, TX 79906
Battery: BRK Brands, Inc. make no warranty, express or implied, written or

oral, including that of merchantability or fitness for any particular purpose

with respect to battery.

RECOMMENDED LOCATIONS FOR 

SMOKE ALARMS

Installing Smoke Alarms in Single-Family Residences
The National Fire Protection Association (NFPA), recommends one Smoke

Alarm on every floor, in every sleeping area, and in every bedroom. In new

construction, the Smoke Alarms must be AC powered and interconnected.

See “Agency Placement Recommendations” for details. For additional cover-

age, it is recommended that you install a Smoke Alarm in all rooms, halls,

storage areas, finished attics, and basements, where temperatures normally

remain between 40˚ F (4.4˚ C) and 100˚ F (37.8˚ C). Make sure no door or

other obstruction could keep smoke from reaching the Smoke Alarms.
More specifically, install Smoke Alarms:

On every level of your home, including finished attics and basements.

Inside every bedroom, especially if people sleep with the door partly or

completely closed.

In the hall near every sleeping area. If your home has multiple sleeping

areas, install a unit in each. If a hall is more than 40 feet long (12 meters),

install a unit at each end.

At the top of the first-to-second floor stairway, and at the bottom 

of the basement stairway.

Specific requirements for Smoke Alarm installation vary from state to state

and from region to region. Check with your local Fire Department for current

requirements in your area. 

It is recommended AC or AC/DC units be inter-

connected for added protection.

INSTALLING SMOKE ALARMS IN MOBILE HOMES & RVS

For minimum security install one Smoke Alarm as close to each sleeping area

as possible. For more security, put one unit in each room. Many older mobile

homes (especially those built before 1978) have little or no insulation. If your

mobile home is not well insulated, or if you are unsure of the amount of 

insulation, it is important to install units on inside walls only. Smoke Alarms

should be installed where temperatures normally remain between 40˚ F (4.4˚ C)

and 100˚ F (37.8˚ C). 

WARNING: Test units used in RVs after the vehicle has been in storage,

before every trip, and once a week while in use. Failure to test units

used in RVs as described may remove your protection.

LIMITATIONS OF SMOKE ALARMS

Smoke Alarms have played a key role in reducing deaths resulting from home

fires worldwide. However, like any warning device, Smoke Alarms can only

work if they are properly located, installed, and maintained, and if smoke

reaches the Alarms. They are not foolproof.
Smoke alarms may not waken all individuals. Practice the escape plan 

at least twice a year, making sure that everyone is involved – from kids to

grandparents. Allow children to master fire escape planning and practice

before holding a fire drill at night when they are sleeping. If children or others

do not readily waken to the sound of the smoke alarm, or if there are infants

or family members with mobility limitations, make sure that someone is

assigned to assist them in fire drill and in the event of an emergency. It is 

recommended that you hold a fire drill while family members are sleeping in

order to determine their response to the sound of the smoke alarm while

sleeping and to determine whether they may need assistance in the event 

of an emergency.
Smoke Alarms cannot work without power. Battery operated units cannot

work if the batteries are missing, disconnected or dead, if the wrong type 

of batteries are used, or if the batteries are not installed correctly. AC units 

cannot work if the AC power is cut off for any reason (open fuse or circuit

breaker, failure along a power line or at a power station, electrical fire that

burns the electrical wires, etc.). If you are concerned about the limitations 

of battery or AC power, install both types of units.
Smoke Alarms cannot detect fires if the smoke does not reach the

Alarms. Smoke from fires in chimneys or walls, on roofs, or on the other side

of closed doors may not reach the sensing chamber and set off the Alarm.

That is why one unit should be installed inside each bedroom or sleeping

area—especially if bedroom or sleeping area doors are closed at night—and

in the hallway between them.
Smoke Alarms may not detect fire on another floor or area of the

dwelling. For example, a stand-alone unit on the second floor may not detect

smoke from a basement fire until the fire spreads. This may not give you

enough time to escape safely. That is why recommended minimum protection

is at least one unit in every sleeping area, and every bedroom on every level

of your dwelling. Even with a unit on every floor, stand-alone units may not

provide as much protection as interconnected units, especially if the fire starts

in a remote area. Some safety experts recommend installing interconnected

AC powered units with battery back-up (see “About Smoke Alarms”) or 

professional fire detection systems, so if one unit senses smoke, all units

alarm. Interconnected units may provide earlier warning than stand-alone 

units since all units alarm when one detects smoke.
Smoke Alarms may not be heard. Though the alarm horn in this unit meets

or exceeds current standards, it may not be heard if: 1) the unit is located 

outside a closed or partially closed door, 2) residents recently consumed

alcohol or drugs, 3) the Alarm is drowned out by noise from stereo, TV, traffic,

air conditioner or other appliances, 4) residents are hearing impaired or sound

sleepers. Special purpose units, like those with visual and audible alarms,

should be installed for hearing impaired residents.
Smoke Alarms may not have time to alarm before the fire itself causes

damage, injury, or death, since smoke from some fires may not reach 

the unit immediately. Examples of this include persons smoking in bed, 

children playing with matches, or fires caused by violent explosions

resulting from escaping gas.
Smoke Alarms are not foolproof. 
Like any electronic device, Smoke Alarms

are made of components that can wear out or fail at any time. You must test

the unit weekly to ensure your continued protection. Smoke Alarms cannot

prevent or extinguish fires. They are not a substitute for property or life 

insurance.
Smoke Alarms have a limited life. The unit should be replaced immediately 

if it is not operating properly. You should always replace a Smoke Alarm after

10 years from date of purchase. Write the purchase date on the space provided

on back of unit.

USING THE SILENCE FEATURE 

The Silence Feature can temporarily quiet an unwanted alarm for up to 15 

minutes.

The Silence Feature does not disable the unit—it makes it temporarily

less sensitive to smoke. For your safety, if smoke around the unit is dense

enough to suggest a potentially dangerous situation, the unit will stay in

alarm or may re-alarm quickly. If you do not know the source of the

smoke, do not assume it is an unwanted alarm. Not responding to an

alarm can result in property loss, injury, or death.
To silence Smoke Alarms in an interconnected series:
1. To silence multiple alarms in an interconnected series, you must press the

Test/Silence button on the unit(s) that triggered the alarm.

2. Once you activate the Silence feature, the Red LED will flash approximately

once every 10 seconds.

3. Pressing the Test/Silence button when in silence will restart the silence

timer.

The Silence Feature on these units can temporarily quiet an unwanted alarm for

up to 15 minutes. To use this feature, press the Test/Silence button on the cover.

If the unit will not silence and no heavy smoke is present, or if it stays in

silence mode continuously, it should be replaced immediately.

Model 3120B

with Battery Back-Up and Silence

AC Powered 

Photo & Ion Smoke Alarm

Input: 120V AC 

~

, 60Hz, 0.07A

Make sure the Alarm is not receiving excessively noisy power. Examples of noisy power could be major appliances on the same circuit, power from a

generator or solar power, light dimmer on the same circuit or mounted near fluorescent lighting. Excessively noisy power may cause damage to your

Alarm.

Low Battery

Alarm “chirp’’ approx.

once/minute

Alarm “chirp’’ approx.

once/minute

Low Battery Latch

Green LED flashing 2

seconds on, 

2 seconds off

Not available

LISTED TO

UL 217 

STANDARD

AGENCY PLACEMENT RECOMMENDATIONS

NFPA 72 (National Fire Code) Chapter 11
“For your information, the National Fire Protection Association's Standard 72,

reads as follows:”
“11.5.1 One- and Two-Family Dwelling Units.”
“11.5.1.1 Smoke Detection. 
Where required by applicable laws, codes, or 

standards for the specified occupancy, approved single- and multiple-station

Smoke Alarms shall be installed as follows: (1) In all sleeping rooms.

Exception: Smoke Alarms shall not be required in sleeping rooms in existing

one- and two-family dwelling units. (2) Outside of each separate sleeping area,

in immediate vicinity of the sleeping rooms. (3) On each level of the dwelling

unit, including basements. Exception: In existing one- and two family dwelling

units, approved Smoke Alarms powered by batteries are permitted.”
“A.11.8.3 Are More Smoke Alarms Desirable? The required number of

Smoke Alarms might not provide reliable early warning protection for those

areas separated by a door from the areas protected by the required Smoke

Alarms. For this reason, it is recommended that the householder consider 

the use of additional Smoke Alarms for those areas for increased protection.

The additional areas include the basement, bedrooms, dining room, furnace

room, utility room, and hallways not protected by the required Smoke Alarms.

The installation of Smoke Alarms in kitchens, unfinished attics, or garages 

is not normally recommended, as these locations occasionally experience

conditions that can result in improper operation.”

California State Fire Marshal (CSFM)

Early warning detection is best achieved by the installation of fire detection

equipment in all rooms and areas of the household as follows: A Smoke Alarm

installed in each separate sleeping area (in the vicinity, but outside bedrooms),

and Heat or Smoke Alarms in the living rooms, dining rooms, bedrooms,

kitchens, hallways, finished attics, furnace rooms, closets, utility and storage

rooms, basements, and attached garages.

LOCATIONS TO AVOID FOR SMOKE ALARMS

For best performance, AVOID installing Smoke Alarms in these areas:

Where combustion particles are produced. Combustion particles form

when something burns. Areas to avoid include poorly ventilated kitchens,

garages, and furnace rooms. Keep units at least 20 feet (6 meters) from

the sources of combustion particles (stove, furnace, water heater, space

heater) if possible. In areas where a 20-foot distance is not possible – in

modular, mobile, or smaller homes, for example – it is recommended 

the Smoke Alarm be placed as far from these fuel-burning sources as 

possible. The placement recommendations are intended to keep these

Alarms at a reasonable distance from a fuel-burning source, and thus

reduce “unwanted” alarms. Unwanted alarms can occur if a Smoke

Alarm is placed directly next to a fuel-burning source. Ventilate these

areas as much as possible.

In air streams near kitchens. Air currents can draw cooking smoke into

the sensing chamber of a Smoke Alarm near the kitchen.

In very damp, humid or steamy areas, or directly near bathrooms with

showers. Keep units at least 10 feet (3 meters) away from showers,

saunas, dishwashers, etc.

Where the temperatures are regularly below 40˚ F (4.4˚ C) or above 

100˚ F (37.8˚ C) including unheated buildings, outdoor rooms, porches, 

or unfinished attics or basements.

In very dusty, dirty, or greasy areas. Do not install a Smoke Alarm directly

over the stove or range. Clean a laundry room unit frequently to keep it

free of dust or lint.

Near fresh air vents, ceiling fans, or in very drafty areas. Drafts can blow

smoke away from the unit, preventing it from reaching sensing chamber.

In insect infested areas. Insects can clog openings to the sensing chamber

and cause unwanted alarms.

Less than 12 inches (305 mm) away from fluorescent lights. Electrical

“noise” can interfere with the sensor.

In “dead air” spaces. “Dead air” spaces may prevent smoke from reaching

the Smoke Alarm.

AVOIDING DEAD AIR SPACES

“Dead air” spaces may prevent smoke from reaching the Smoke Alarm. To

avoid dead air spaces, follow the installation recommendations below.
On ceilings, install Smoke Alarms as close to the center of the ceiling as 

possible. If this is not possible, install the Smoke Alarm at least 4 inches 

(102 mm) from the wall or corner.
For wall mounting (if allowed by building codes), the top edge of Smoke

Alarms should be placed between 4 inches (102 mm) and 12 inches (305 mm)

from the wall/ceiling line, below typical “dead air” spaces.
On a peaked, gabled, or cathedral ceiling, install the first Smoke Alarm 

within 3 feet (0.9 meters) of the peak of the ceiling, measured horizontally.

Additional Smoke Alarms may be required depending on the length, angle,

etc. of the ceiling's slope. Refer to NFPA 72 for details on requirements for

sloped or peaked ceilings.

SPECIAL COMPLIANCE CONSIDERATIONS

This Smoke Alarm alone is not a suitable substitute for complete fire

detection systems in places housing many people—like apartment 

buildings, condominiums, hotels, motels, dormitories, hospitals, long-

term health care facilities, nursing homes, day care facilities, or group

homes of any kind—even if they were once single-family homes. It is not

a suitable substitute for complete fire detection systems in warehouses,

industrial facilities, commercial buildings, and special-purpose non-resi-

dential buildings which require special fire detection and alarm systems.

Depending on the building codes in your area, this Smoke Alarm may be

used to provide additional protection in these facilities.
The following information applies to all four types of buildings listed below: 
In new construction, most building codes require the use of AC or AC/DC 

powered Smoke Alarms only. AC, AC/DC, or DC powered Smoke Alarms can be

used in existing construction as specified by local building codes. Refer to NFPA

72 (National Fire Alarm Code) and NFPA 101 (Life Safety Code), local building

codes, or consult your Fire Department for detailed fire protection requirements

in buildings not defined as “households.”
1. Single-Family Residence: 

Single family home, townhouse. It is recommended Smoke Alarms be installed

on every level of the home, in every bedroom, and in each bedroom hallway.
2. Multi-Family or Mixed Occupant Residence: 

Apartment building, condominium. This Smoke Alarm is suitable for use in

individual apartments or condos, provided a primary fire detection system

already exists to meet fire detection requirements in common areas like 

lobbies, hallways, or porches. Using this Smoke Alarm in common areas may

not provide sufficient warning to all residents or meet local fire protection 

ordinances/regulations.
3. Institutions: 

Hospitals, day care facilities, long-term health care facilities. This Smoke 

Alarm is suitable for use in individual patient sleeping/resident rooms, 

provided a primary fire detection system already exists to meet fire detection

requirements in common areas like lobbies, hallways, or porches. Using this

Smoke Alarm in common areas may not provide sufficient warning to all 

residents or meet local fire protection ordinances/regulations.
4. Hotels and Motels: 

Also boarding houses and dormitories. This Smoke Alarm is suitable for use

inside individual sleeping/resident rooms, provided a primary fire detection 

system already exists to meet fire detection requirements in common areas 

like lobbies, hallways, or porches. Using this Smoke Alarm in common areas

may not provide sufficient warning to all residents or meet local fire protection

ordinances/regulations.

ABOUT SMOKE ALARMS

Battery (DC) operated Smoke Alarms: Provide protection even when 

electricity fails, provided the batteries are fresh and correctly installed. Units

are easy to install, and do not require professional installation. They do not,

however, provide interconnected functionality.
AC powered Smoke Alarms: Can be interconnected so if one unit senses

smoke, all units alarm. They do not operate if electricity fails. 

AC with battery (DC) back-up: will operate if electricity fails, provided the

batteries are fresh and correctly installed. AC and AC/DC units must be

installed by a qualified electrician.
Wireless Interconnected Alarms: Offer the same interconnected functionality

as with hardwired alarms, without wires. Units are easy to install and do not

require professional installation. They provide protection even when electricity

fails, provided the batteries are fresh and correctly installed.
Smoke Alarms for Solar or Wind Energy users and battery backup power

systems: AC powered Smoke Alarms should only be operated with true or

pure sine wave inverters. Operating this Smoke Alarm with most battery-

powered UPS (uninterruptible power supply) products or square wave or

“quasi sine wave” inverters 

will damage the Alarm. If you are not sure about

your inverter or UPS type, please consult with the manufacturer to verify.
Smoke Alarms for the hearing impaired: Special purpose Smoke Alarms

should be installed for the hearing impaired. They include a visual alarm and

an audible alarm horn, and meet the requirements of the Americans With

Disabilities Act. These units can be interconnected so if one unit senses

smoke, all units alarm.

Continued...

ABOUT SMOKE ALARMS, Continued
Smoke alarms are not to be used with detector guards unless the 

combination has been evaluated and found suitable for that purpose.
All these Smoke Alarms are designed to provide early warning of fires if 

located, installed and cared for as described in the user’s manual, and if

smoke reaches the Alarm. If you are unsure which type of unit to install, refer

to NFPA (National Fire Protection Association) 72 (National Fire Alarm Code)

and NFPA 101 (Life Safety Code). National Fire Protection Association, One

Batterymarch Park, Quincy, MA 02269-9101. Local building codes may also

require specific units in new construction or in different areas of the home.

2

1

Choosing a replacement battery:
Your Smoke/CO Alarm requires two “AA” Energizer E91 batteries. 

These batteries are available at many local retail stores.

Actual battery service life depends on the Alarm and the environment in which

it is installed. All the batteries specified above are acceptable replacement

batteries for this unit. Regardless of the manufacturer’s suggested battery life,

you MUST replace the battery immediately once the unit starts “chirping”

(the “low battery warning”).
To replace the batteries (without removing Alarm from the ceiling or wall):
1. Open the battery compartment.
2. Press tabs A and B as shown in the diagram

and remove each battery.

3. Insert the new batteries, making sure 

they snap completely into the battery 

compartment. Match the terminals on the

ends of the batteries with the terminals on

the unit.

4. Close the battery compartment, and then

test the unit by pressing the Test/Silence 

button.

AB

SILENCING THE LOW BATTERY WARNING

This Silence Feature can temporarily quiet the low battery warning “chirp” for

up to 8 hours. Press the Test/Silence button on the Alarm cover until you hear

the acknowledge “chirp”.
Once the low battery warning “chirp” silence feature is activated, the unit

continues to flash the green light once a minute for approximately 8 hours.

After 8 hours, the low battery “chirp” will resume. The Alarm will continue 

to operate as long as AC power is supplied. However, 

replace the batteries

as soon as possible, to maintain protection in event of a power outage.
To silence Alarms in an interconnected series:

To silence an interconnected series of Smoke/CO Alarms, you must press the

Test/Silence button on the initiating alarm (The unit with the flashing red light;

the red light will be off on all other Alarms.). If you press the Test/Silence on

any other Alarm, it will only silence that unit, not the whole interconnected

series.

LATCHING FEATURE

Alarm Latch is activated after an Alarm is exposed to alarm levels of smoke.

This feature will only work with AC power. After smoke levels drop below alarm

levels, the

Red LED will begin flashing 2 seconds on, 2 seconds off unless

reset by test/silence button.
This feature helps emergency responders, investigators, or service 

technicians identify which unit(s) in your home were exposed to alarm levels

of smoke. This can help investigators pinpoint the source of smoke.
Interconnected Alarms. Latching Alarm Indicator shows which Alarm(s) in the

series were exposed to alarm levels of smoke. The Latching Alarm Indicator

stays ON until you clear it, so it can alert you to an alarm that occurred while

you were away from home, even though smoke present in the air has dropped

below alarm levels.
Low Battery Latch is activated when the Alarm is in the "low battery 

condition". When this occurs, the 

Green LED flashes 2 seconds on, 2 

seconds off. This feature is designed to help you identify which Alarm needs

to have the battery replaced. Although, the Alarm will sound the low battery

chirp approximately once every minute, sometimes during the initial stages 

of "low battery", the Alarm will chirp in greater intervals than one minute,

sometimes up to several hours, until the battery reaches a steady low battery

level. This innovative feature eliminates the frustration of waiting for and/or

identifying which unit is chirping.

“SMART INTERCONNECT” FEATURE

This Alarm includes "Smart Interconnect" which enables the Alarm to be

interconnected with other First Alert

®

and BRK Smoke, Heat, and "Smart

Interconnect" Smoke, Smoke/CO and CO Alarms. When smoke is detected,

all Alarms will sound the smoke horn pattern. When CO is detected, "Smart

Interconnect" Alarms will sound the CO horn pattern. Alarms that do not have

the "Smart Interconnect" feature will remain silent during a CO alarm.

Model 3120B

Printed in Mexico

M08-0224-000   

11/10

IMPORTANT! PLEASE READ CAREFULLY AND SAVE.

This user’s manual contains important information about your Smoke

Alarm’s operation. If you are installing this Smoke Alarm for use by 

others, you must leave this manual—or a copy of it—with the end user.

INTRODUCTION

Thank you for choosing First Alert

®

for your Smoke Alarm needs. You have 

purchased a state of the art Smoke Alarm designed to provide you with an

early warning of a fire. Please take the time to read this manual and make

this Smoke Alarm an integral part of your family’s safety plan.

Key Features of the 3120B Photo & Ion Combo Smoke Alarm:
Photo & Ion Smoke Sensors: 
Dual photoelectric and ionization smoke 

sensing technologies for optimal sensing of smoke particles produced in

both flaming and smoldering fires.
Optipath 360 Technology

TM

Patented technology provides 360˚ of direct

access to the smoke sensor.
Two Silence Features: Low Battery Silence temporarily silences low 

battery chirp for up to eight hours before replacing low battery. 

Alarm Silence silences an unwanted alarm for several minutes.
Two Latching Features: Alarm Latch remembers which unit initiated an

alarm. 

Low Battery Latch visually identifies which unit is in low battery 

condition.
Perfect Mount: Mounting bracket keeps alarm secure over a wide rotation

range to allow for perfect alignment.
Battery back-up: Keeps alarm functioning during a power interruption 

provided batteries are fresh and installed properly.
© 2010 BRK Brands, Inc. All rights reserved. Distributed by BRK Brands, Inc.

3901 Liberty Street Road, Aurora, IL 60504-8122

Consumer Affairs: (800) 323-9005

www.firstalert.com   •   www.brkelectronics.com

FIRE SAFETY TIPS

Follow safety rules and prevent hazardous situations: 1) Use smoking 

materials properly. Never smoke in bed. 2) Keep matches or lighters away 

from children; 3) Store flammable materials in proper containers; 

4) Keep electrical appliances in good condition and don’t overload electrical

circuits; 5) Keep stoves, barbecue grills, fireplaces and chimneys grease- 

and debris-free; 6) Never leave anything cooking on the stove unattended; 

7) Keep portable heaters and open flames, like candles, away from flammable

materials; 8) Don’t let rubbish accumulate.
Keep alarms clean, and test them weekly. Replace alarms immediately if they

are not working properly. Smoke Alarms that do not work cannot alert you to a

fire. Keep at least one working fire extinguisher on every floor, and an additional

one in the kitchen. Have fire escape ladders or other reliable means of escape

from an upper floor in case stairs are blocked.

BEFORE YOU INSTALL THIS SMOKE ALARM

IMPORTANT! Read “Recommended Locations for Smoke Alarms” and

“Locations to Avoid for Smoke Alarms” before beginning. This unit monitors

the air, and when smoke reaches its sensing chamber, it alarms. It can give

you more time to escape before fire spreads. This unit can ONLY give an early

warning of developing fires if it is installed, maintained and located where

smoke can reach it, and where all residents can hear it, as described in this

manual. This unit will not sense gas, heat, or flame. It cannot prevent or 

extinguish fires.
Understand The Different Type of Smoke Alarms

Battery powered or electrical? Different Smoke Alarms provide different

types of protection. See “About Smoke Alarms” for details.

Know Where To Install Your Smoke Alarms

Fire Safety Professionals recommend at least one Smoke Alarm on every

level of your home, in every bedroom, and in every bedroom hallway or

separate sleeping area. See “Recommended Locations For Smoke Alarms”

and “Locations To Avoid For Smoke Alarms” for details.

Know What Smoke Alarms Can and Can’t Do

A Smoke Alarm can help alert you to fire, giving you precious time to

escape. It can only sound an alarm once smoke reaches the sensor. 

See “Limitations of Smoke Alarms” for details.

Check Your Local Building Codes

This Smoke Alarm is designed to be used in a typical single-family home. 

It alone will not meet requirements for boarding houses, apartment 

buildings, hotels or motels. See “Special Compliance Considerations” 

for details.

5

6

7

1

2

3

All First Alert

®

and BRK

®

Smoke Alarms conform to regulatory 

requirements, including UL217 and are designed to detect particles of

combustion. Smoke particles of varying number and size are produced

in all fires.

Ionization technology is generally more sensitive than photoelectric

technology at detecting small particles, which tend to be produced

in greater amounts by flaming fires, which consume combustible

materials rapidly and spread quickly. Sources of these fires may include

paper burning in a wastebasket, or a grease fire in the kitchen.

Photoelectric technology is generally more sensitive than ionization

technology at detecting large particles, which tend to be produced in

greater amounts by smoldering fires, which may smolder for hours

before bursting into flame. Sources of these fires may include cigarettes

burning in couches or bedding.
For maximum protection, use both types of Smoke Alarms on each

level and in every bedroom of your home.

USER’S MANUAL

SMOKE ALARMS

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

• This unit will not alert hearing impaired residents. It is recom-

mended that you install special units which use devices like

flashing strobe lights to alert hearing impaired residents.

• Installation of this unit must conform to the electrical codes in 

your area; Articles 210 and 300.3 (B) of NFPA 70 (NEC), NFPA 72,

NFPA 101; SBC (SBCCI); UBC (ICBO); NBC (BOCA); OTFDC (CABO),

and any other local or building codes that may apply. Wiring and

installation must be performed by a licensed electrician. Failure to

follow these guidelines may result in injury or property damage.

• This unit must be powered by a 24-hour, 120VAC pure sine wave

60Hz circuit. Be sure the circuit cannot be turned off by a switch,

dimmer, or ground fault circuit interrupter. Failure to connect this

unit to a 24-hour circuit may prevent it from providing constant

protection.

• This Smoke Alarm must have AC or battery power to operate.

If the AC power fails, battery back-up will allow the alarm to

sound for at least 4 minutes. If AC power fails and the battery is

weak, protection should last for at least 7 days. If AC power fails

and the battery is dead or missing, the alarm cannot operate.

• Never disconnect the power from an AC powered unit to stop an

unwanted alarm. Doing so will disable the unit and remove your

protection. In the case of a true unwanted alarm open a window

or fan the smoke away from the unit. The alarm will reset auto-

matically when it returns to normal operation. Never remove the

batteries from a battery operated unit to stop an unwanted alarm

(caused by cooking smoke, etc.). Instead open a window or fan

the smoke away from the unit. The alarm will reset automatically.

• Connect this unit ONLY to other compatible units. See “How To

Install This Smoke Alarm” for details. Do not connect it to any

other type of alarm or auxiliary device. Connecting anything else

to this unit may damage it or prevent it from operating properly.

• This Smoke Alarm has a battery drawer which resists closing

unless a battery is installed. This warns you the unit will not

operate under DC power without a battery.

• Do not stand too close to the unit when the alarm is sounding. 

It is loud to wake you in an emergency. Exposure to the horn at

close range may harm your hearing.

• Do not paint over the unit. Paint may clog the openings to the

sensing chambers and prevent the unit from operating properly.

The Mounting Bracket:

To remove the mounting bracket from the Smoke

Alarm base, hold the Smoke Alarm base firmly 

and twist the mounting bracket counterclockwise.

The mounting bracket installs onto the junction box.

It has a variety of screw slots to fit most boxes.

The Power Connector: 

The power connector plugs into a power input block on

the Smoke Alarm. It supplies the unit with AC power.

• The black wire is “hot.” 
• The white wire is neutral.
• The orange wire is used for interconnect.

If you need to remove the power connector, turn 

POWER OFF first. Insert a flat screwdriver blade

between the power connector and the security tab

inside the power input block. Gently pry back the tab

and pull the connector free.

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The Parts of This Unit
1

Mounting Bracket

2

Mounting Slots

3

Locking Pins (break out of bracket)

4

Hot (Black) AC Wire

5

Neutral (White) AC Wire

6

Interconnect (Orange) Wire

7

Quick-Connect Power Connector

8

Turn this way to remove from bracket

9

Turn this way to attach to bracket

10 Slide-Out Battery Drawer

The basic installation of this Smoke Alarm is similar whether you want to

install one Smoke Alarm, or interconnect more than one Smoke Alarm. 

If you are interconnecting more than one Smoke Alarm, you MUST read

“Special Requirements For Interconnected Smoke Alarms” below before

you begin installation.

ELECTRICAL SHOCK HAZARD. Turn off power to the area where you 

will install this unit at the circuit breaker or fuse box before beginning

installation. Failure to turn off the power before installation may result 

in serious electrical shock, injury or death.
1. Remove the mounting bracket from the base, and attach it to the 

junction box.
Activate the battery back-up by removing the “Pull to Activate Battery

Back-Up” tab. Or, install battery back-up. Battery back-up cannot work

until you install the battery in the correct position (Match “+” to “+” and

“-” to “-”).
Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

2. Using wire nuts, connect the power connector to the household wiring.

3. Plug the power connector into the back of the Smoke Alarm.
4. Position the base of the Smoke Alarm over the mounting bracket and

turn. The Alarm can be positioned over the bracket every 90°.

Turn the Smoke Alarm clockwise (right) until the unit is in place.

5. Check all connections.

Improper wiring of the power connector or the wiring leading to the

power connector will cause damage to the Alarm and may lead to a

non-functioning Alarm.

ELECTRICAL SHOCK HAZARD. Do not restore power until all Smoke

Alarms are completely installed. Restoring power before installation is

complete may result in serious electrical shock, injury or death.
6. Make sure the Smoke Alarm is receiving AC power. Under normal 

operation, the Green power indicator light will shine continuously. 

7. If the Green power indicator light does not light, 

TURN OFF POWER 

TO THE JUNCTION BOX and recheck all connections. If all connections

are correct and the Green power indicator still does not light when you

restore the power, the unit should be replaced immediately.

8. Test each Smoke Alarm. Press and hold the Test/Silence button until the

unit alarms. 

When testing a series of interconnected units you must

test each unit individually. Make sure all units alarm when each one

is tested.

Continued...

8. Continued

If any unit in the series does not alarm, 

TURN OFF POWER and recheck

connections. If it does not alarm when you restore power, replace it 

immediately.

Special Requirements For Interconnected Smoke Alarms

• Failure to meet any of the above requirements could damage the

units and cause them to malfunction, removing your protection.

• AC and AC/DC Smoke Alarms can be interconnected. Under AC

power, all units will alarm when one senses smoke. When power 

is interrupted, only the AC/DC units in the series will continue to

send and receive signals. AC powered Smoke Alarms will not

operate.

Interconnected units can provide earlier warning of fire than stand-alone units,

especially if a fire starts in a remote area of the dwelling. If any unit in the series

senses smoke, all units will alarm. To determine which Smoke Alarm initiated an

alarm, see table:

During an Alarm:
On Initiating Alarm(s)

Red LED(s) flashes (flash) rapidly

On All Other Alarms

Red LED is Off

After an Alarm (Latching):
On Initiating Alarm(s)

Red LED(s) flash 3 times, spaced one second apart. 

The pattern repeats approximately every 45 seconds.

On All Other Alarms

Green LED(s) On, Red LED(s) Off

Interconnect units within a single family residence only. Otherwise all 

households will experience unwanted alarms when you test any unit in the

series. Interconnected units will only work if they are wired to compatible

units and all requirements are met. This unit is designed to be compatible

with: 

First Alert

®

Smoke Alarm Models SA4120, SA4121B, SA100B, SA520

and 

BRK

®

Smoke Alarm Models 3120B, 9120, 9120B, SC6120B, SC9120B,

7010, 7010B, 7010BSL, 7020B, SC7010B, SC7010BV, 100S, 4120, 4120B,

4120SB; 

BRK

®

CO Alarm Models CO5120BN, CO5120PDBN; BRK

®

Heat

Alarm Models HD6135F and HD6135FB; BRK

®

Auxiliary Devices Models

RM3 and RM4 (Relay Modules), SL177 (Strobe Light). 

See www.brkelectronics.com for most current interconnect list.

Interconnected units must meet ALL of the following requirements:

• A maximum of 18 compatible units may be interconnected 

(Maximum of 12 Smoke Alarms).

• The same fuse or circuit breaker must power all interconnected units.
• The total length of wire interconnecting the units should be less than

1000 feet (300 meters). This type of wire is commonly available at

Hardware and Electrical Supply stores.

• All wiring must conform to all local electrical codes and NFPA 70 (NEC).

Refer to NFPA 72, NFPA 101, and/or your local building code for further 

connection requirements.

HOW TO INSTALL THIS SMOKE ALARM

THE PARTS OF THIS SMOKE ALARM

This Smoke Alarm is designed to be mounted on any standard wiring junction box up to a 4-inch (10 cm) size, on either the ceiling or wall (if allowed by local codes).

Read “Recommended Locations For Smoke Alarms” and “Locations to Avoid For Smoke Alarms” before you begin installation. 

Tools you will need:  • Needle-nose pliers or utility knife • Standard Flathead screwdriver.

FOLLOW THESE INSTALLATION STEPS

STAND-ALONE ALARM ONLY:

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Tuck the orange wire inside the junction box. It is used for interconnect

only.

INTERCONNECTED UNITS ONLY:
Strip off about 1/2” (12 mm) of the plastic coating on the orange wire

on the power connector.

Connect the white wire on the power connector to the neutral wire in

the junction box.

Connect the black wire on the power connector to the hot wire in the

junction box.

Connect the orange wire on the power connector to the interconnect

wire in the junction box. Repeat for each unit you are interconnecting.

Never connect the hot or neutral wires in the junction box to the orange

interconnect wire. Never cross hot and neutral wires between Alarms.

STAND-ALONE ALARM ONLY:

If you are only installing one Smoke Alarm, restore power to the 

junction box.

INTERCONNECTED UNITS ONLY:

If you are interconnecting multiple Smoke Alarms, repeat steps 

1-5 for each Smoke Alarm in the series. When you are finished,

restore power to the junction box.

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!

"

"

#

A. Unswitched 120VAC 

60 Hz source

B. To additional units; Maximum = 18 total

(Maximum 12 Smoke Alarms)

1. Smoke Alarm
2. Ceiling or Wall
3. Power Connector

4. Wire Nut
5. Junction Box
6. Neutral Wire (Wht)

7. Interconnect Wire

(Orange)

8. Hot Wire (Blk) 

4

OPTIONAL LOCKING FEATURES

The locking features are designed to discourage unauthorized removal of the batteries or Alarm. It is not necessary to activate the locks in single-family 

households where unauthorized battery or Alarm removal is not a concern.
These Smoke Alarms have two separate locking features: one to lock the battery compartment, and the other to lock the Smoke Alarm 

to the mounting bracket. You can choose to use either feature independently, or use them both.
Tools you will need: • Needle-nose pliers or utility knife  • Standard Flathead screwdriver.
Both locking features use locking pins, which are molded into the mounting bracket. Using needle-nose pliers or a utility knife, remove

one or both pins from the mounting bracket, depending on how many locking features you want to use.

To permanently remove either lock, insert a flathead screwdriver between the locking pin and the lock, and pry the pin out of the lock.

TO LOCK THE BATTERY COMPARTMENT

Do not lock the battery compartment until you have installed the 

batteries and tested the battery back-up.
1. Push and hold Test button until the alarm sounds: 3 beeps, pause, 

3 beeps, pause. LED flashes once every second.

If the unit does not alarm during testing, DO NOT lock the battery

compartment! Install new batteries and test again. If the Smoke 

Alarm still does not alarm, replace it immediately.

2. Using needle-nose pliers or a utility knife, detach one locking pin 

from the mounting bracket.

3. Push the locking pin through the hole near the battery drawer on the

back of the Smoke Alarm.

TO UNLOCK THE BATTERY COMPARTMENT

Once the Smoke Alarm is installed, you must disconnect it from the AC power

before unlocking the battery compartment.

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse box.

Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.
1. Remove the Smoke Alarm from the mounting

bracket. If the unit is locked to the bracket, see

the section “To Unlock the Mounting Bracket.”

2. Disconnect the power connector by gently prying

it away from the back of the Smoke Alarm.

3. Insert a flathead screwdriver under the head 

of the locking pin, and gently pry it out of the 

battery compartment lock. (If you plan to relock

the battery compartment, save the locking pin.)

4. To relock the battery compartment, close the 

battery door and reinsert locking pin in lock.

5. Reconnect the power connector to the back of the Smoke Alarm, reattach

the Smoke Alarm to the mounting bracket, and restore the power.

When replacing the batteries, always test the Smoke Alarm before relocking

the battery compartment.

TO UNLOCK THE MOUNTING BRACKET

ELECTRICAL SHOCK HAZARD. Turn off the power to the area where the

Smoke Alarm is installed before removing it from the mounting bracket.

Failure to turn off the power first may result in serious electrical shock,

injury or death.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the Test/Silence button for 5-10 seconds to 

discharge the branch circuit.

1. Insert a flathead screwdriver between the

mounting bracket pin and the mounting bracket.

2. Pry the Smoke Alarm away from the bracket by

turning both the screwdriver and the Smoke

Alarm counterclockwise (left) at the same time.

TO LOCK THE MOUNTING BRACKET

1. Using needle-nose pliers, detach one locking pin from mounting bracket.

2. Insert the locking pin into the lock located

opposite from the battery drawer as shown

in the diagram.

3. When you attach the Smoke Alarm to the mounting bracket, the locking

pin’s head will fit into a notch on the bracket.

Locking Features (Continued)

Printed in Mexico   M08-0224-000   

11/10

First Alert

®

is a registered trademark of the First Alert Trust.

BRK

®

is a registered trademark of BRK Brands, Inc.

WEEKLY TESTING

NEVER use an open flame of any kind to test this unit. You might

accidentally damage or set fire to the unit or to your home. The built-

in test switch accurately tests the unit’s operation as required by

Underwriters Laboratories, Inc. (UL).

If the Alarm ever fails to test properly, replace it immediately.

Products under warranty may be returned to the manufacturer 

for replacement. See “Limited Warranty” at the end of this manual.

DO NOT stand close to the Alarm when the horn is sounding. Exposure

at close range may be harmful to your hearing. When testing, step away

when horn starts sounding.
It is important to test this unit every week to make 

sure it is working properly. Using the test button is the

recommended way to test this Smoke Alarm.
Press and hold the Test/Silence button on the cover of the

unit until the alarm sounds (the unit may continue to alarm

for a few seconds after you release the button). If it does

not alarm, make sure the unit is receiving power and test 

it again. If it still does not alarm, replace it immediately.
During testing, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause. LED flashes once every second.
When testing a series of interconnected units you must test each unit 

individually. Make sure all units alarm when each one is tested.

REGULAR MAINTENANCE

Use only the replacement batteries listed below. The unit may not 

operate properly with other batteries. Never use rechargeable batteries

since they may not provide a constant charge.
This unit has been designed to be as maintenance-free as possible, but there

are a few simple things you must do to keep it working properly:

Test it at least once a week.

Clean the Smoke Alarm at least once a month; gently vacuum the 

outside of the Smoke Alarm using your household vacuum’s soft brush

attachment. Test the Smoke Alarm. Never use water, cleaners or solvents

since they may damage the unit.

If the Smoke Alarm becomes contaminated by excessive dirt, dust and/or

grime, and cannot be cleaned to avoid unwanted alarms, replace the 

unit immediately.

Relocate the unit if it sounds frequent unwanted alarms. See “Locations 

To Avoid For Smoke Alarms” for details.

When the battery back-up becomes weak, the Smoke Alarm will “chirp”

about once a minute (the low battery warning). This warning should last 7

days, but you should replace the batteries immediately to continue your

protection.

UNDERSTANDING THE INDICATOR LIGHTS 
AND ALARM HORN PATTERNS

NOTE: When power is applied, unit(s) may alarm momentarily.
*
When any Smoke Alarm in an interconnected series triggers an alarm, its

red LED will flash rapidly. The red LEDs will remain OFF on any remaining

alarms in the series. This feature helps responders identify which unit(s) 

triggered the alarm.

Latching Alarm

Red LED flashing 2 

seconds on, 

2 seconds off

Not available

AC Power 

DC Power

Normal Operation

Constant Green LED
No Audible Alarm

Flashing Green LED

once/minute
No Audible Alarm

Test Condition

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Silence Mode

Rapidly Flashing 

Red LED
Audible Alarm Off

Rapidly Flashing 

Red LED
Audible Alarm Off

Alarm Condition*

(Initiating Unit)

Rapidly Flashing 

Red LED
Audible Alarm

Rapidly Flashing 

Red LED
Audible Alarm

Alarm Condition*

(Remote Units)

Constant Green LED
Audible Alarm

Green LED Off
Audible Alarm

IF THIS SMOKE ALARM SOUNDS

RESPONDING TO AN ALARM

During an alarm, you will hear a loud, repeating horn pattern: 3 beeps,

pause, 3 beeps, pause.

• If the unit alarms and you are not testing the unit, it is warning you of a

potentially dangerous situation that requires your immediate attention.

NEVER ignore any alarm. Ignoring the alarm may result in injury or

death.

• Never disconnect the AC power to quiet an unwanted alarm.

Disconnecting the power disables the Alarm so it cannot sense

smoke. This will remove your protection. Instead, open a window or

fan the smoke away from the unit. The Alarm will reset automatically.

• If the unit alarms get everyone out of the house immediately.

• ELECTRICAL SHOCK HAZARD: Attempting to disconnect the power

connector from the unit when the power is on may result in electrical

shock, serious injury or death.

When an interconnected system of AC powered units is in alarm, the alarm

indicator light on the unit(s) that initiated the alarm will blink rapidly. It will

remain OFF on any remaining units.
If the unit alarms, get everyone out of the dwelling immediately.
If the unit alarms and you are certain that the source of smoke is not a fire—

cooking smoke or an extremely dusty furnace, for example—open a nearby 

window or door and fan the smoke away from the unit (Use the Silence Feature

to silence the Alarm). This will silence the alarm, and once the smoke clears the

unit will reset itself automatically.

WHAT TO DO IN CASE OF FIRE

Don’t panic; stay calm. Follow your family escape plan.

Get out of the house as quickly as possible. Don’t stop to 

get dressed or collect anything.

Feel doors with the back of your hand before opening them. 

If a door is cool, open it slowly. Don’t open a hot door. Keep doors 

and windows closed, unless you must escape through them.

Cover your nose and mouth with a cloth (preferably damp). 

Take short, shallow breaths.

Meet at your planned meeting place outside your home, 

and do a head count to make sure everybody got out safely.

Call the Fire Department as soon as possible from outside. 

Give your address, then your name.

Never go back inside a burning building for any reason.

Contact your Fire Department for ideas on making your home safer.

Alarms have various limitations. See "Limitations of Smoke Alarms" for

details.

IF YOU SUSPECT A PROBLEM

Smoke Alarms may not operate properly because of dead, missing or weak

batteries, a build-up of dirt, dust or grease on the Smoke Alarm cover, or

installation in an improper location. Clean the Smoke Alarm as described in

“Regular Maintenance,” and install fresh batteries, then test the Smoke Alarm

again. If it fails to test properly when you use the test button, or if the problem

persists, replace the Smoke Alarm immediately.

If you hear a “chirp” approximately once a minute, replace the 

batteries.

If you experience frequent non-emergency alarms (like those caused

by cooking smoke), try relocating the Smoke Alarm.

If the alarm sounds when no smoke is visible, try cleaning or 

relocating the Smoke Alarm. The cover may be dirty.

If the alarm does not sound during testing, make sure it is receiving

AC power from the household current.

Always discharge the branch circuit before servicing an AC or AC/DC

Smoke Alarm. First, turn off the AC power at the circuit breaker or fuse

box. Next, remove the batteries from Smoke Alarms with battery back-up.

Finally, press and hold the test button for 5-10 seconds to discharge the

branch circuit.

If the Smoke Alarm is still not operating properly, and it is still under warranty,

please see “How to Obtain Warranty Service” in the Limited Warranty.

Do not try fixing the alarm yourself – this will void your warranty!

LIMITED WARRANTY

BRK Brands, Inc., ("BRK") the maker of First Alert

®

brand and BRK

®

brand

products, warrants that for a period of ten years from the date of purchase,

this product will be free from defects in material and workmanship. 

BRK, at its option, will repair or replace this product or any component of

the product found to be defective during the warranty period. Replacement

will be made with a new or remanufactured product or component. If the

product is no longer available, replacement may be made with a similar

product of equal or greater value. This is your exclusive warranty.
This warranty is valid for the original retail purchaser from the date of initial

retail purchase and is not transferable. Keep the original sales receipt. 

Proof of purchase is required to obtain warranty performance. 

BRK dealers, service centers, or retail stores selling BRK products do not

have the right to alter, modify or any way change the terms and conditions

of this warranty.
This warranty does not cover normal wear of parts or damage resulting

from any of the following: negligent use or misuse of the product, use on

improper voltage or current, use contrary to the operating instructions, 

disassembly, repair or alteration by anyone other than BRK or an authorized

service center. Further, the warranty does not cover Acts of God, such as

fire, flood, hurricanes and tornadoes or any batteries that are included with

this unit.
BRK shall not be liable for any incidental or consequential damages

caused by the breach of any express or implied warranty. Except to the

extent prohibited by applicable law, any implied warranty of merchantability

or fitness for a particular purpose is limited in duration to the duration of

the above warranty. Some states, provinces or jurisdictions do not allow

the exclusion or limitation of incidental or consequential damages or 

limitations on how long an implied warranty lasts, so the above limitations

or exclusion may not apply to you. This warranty gives you specific legal

rights, and you may also have other rights that vary from state to state or

province to province.
How to Obtain Warranty Service
Service: 
If service is required, do not return the product to your retailer. 

In order to obtain warranty service, contact the Consumer Affairs Division

at 1-800-323-9005, 7:30 AM - 5:00 PM Central Standard Time, Monday

through Friday. To assist us in serving you, please have the model number

and date of purchase available when calling.  

For Warranty Service return to:

BRK Brands, Inc., 25 Spur Drive, El Paso, TX 79906
Battery: BRK Brands, Inc. make no warranty, express or implied, written or

oral, including that of merchantability or fitness for any particular purpose

with respect to battery.

RECOMMENDED LOCATIONS FOR 

SMOKE ALARMS

Installing Smoke Alarms in Single-Family Residences
The National Fire Protection Association (NFPA), recommends one Smoke

Alarm on every floor, in every sleeping area, and in every bedroom. In new

construction, the Smoke Alarms must be AC powered and interconnected.

See “Agency Placement Recommendations” for details. For additional cover-

age, it is recommended that you install a Smoke Alarm in all rooms, halls,

storage areas, finished attics, and basements, where temperatures normally

remain between 40˚ F (4.4˚ C) and 100˚ F (37.8˚ C). Make sure no door or

other obstruction could keep smoke from reaching the Smoke Alarms.
More specifically, install Smoke Alarms:

On every level of your home, including finished attics and basements.

Inside every bedroom, especially if people sleep with the door partly or

completely closed.

In the hall near every sleeping area. If your home has multiple sleeping

areas, install a unit in each. If a hall is more than 40 feet long (12 meters),

install a unit at each end.

At the top of the first-to-second floor stairway, and at the bottom 

of the basement stairway.

Specific requirements for Smoke Alarm installation vary from state to state

and from region to region. Check with your local Fire Department for current

requirements in your area. 

It is recommended AC or AC/DC units be inter-

connected for added protection.

INSTALLING SMOKE ALARMS IN MOBILE HOMES & RVS

For minimum security install one Smoke Alarm as close to each sleeping area

as possible. For more security, put one unit in each room. Many older mobile

homes (especially those built before 1978) have little or no insulation. If your

mobile home is not well insulated, or if you are unsure of the amount of 

insulation, it is important to install units on inside walls only. Smoke Alarms

should be installed where temperatures normally remain between 40˚ F (4.4˚ C)

and 100˚ F (37.8˚ C). 

WARNING: Test units used in RVs after the vehicle has been in storage,

before every trip, and once a week while in use. Failure to test units

used in RVs as described may remove your protection.

LIMITATIONS OF SMOKE ALARMS

Smoke Alarms have played a key role in reducing deaths resulting from home

fires worldwide. However, like any warning device, Smoke Alarms can only

work if they are properly located, installed, and maintained, and if smoke

reaches the Alarms. They are not foolproof.
Smoke alarms may not waken all individuals. Practice the escape plan 

at least twice a year, making sure that everyone is involved – from kids to

grandparents. Allow children to master fire escape planning and practice

before holding a fire drill at night when they are sleeping. If children or others

do not readily waken to the sound of the smoke alarm, or if there are infants

or family members with mobility limitations, make sure that someone is

assigned to assist them in fire drill and in the event of an emergency. It is 

recommended that you hold a fire drill while family members are sleeping in

order to determine their response to the sound of the smoke alarm while

sleeping and to determine whether they may need assistance in the event 

of an emergency.
Smoke Alarms cannot work without power. Battery operated units cannot

work if the batteries are missing, disconnected or dead, if the wrong type 

of batteries are used, or if the batteries are not installed correctly. AC units 

cannot work if the AC power is cut off for any reason (open fuse or circuit

breaker, failure along a power line or at a power station, electrical fire that

burns the electrical wires, etc.). If you are concerned about the limitations 

of battery or AC power, install both types of units.
Smoke Alarms cannot detect fires if the smoke does not reach the

Alarms. Smoke from fires in chimneys or walls, on roofs, or on the other side

of closed doors may not reach the sensing chamber and set off the Alarm.

That is why one unit should be installed inside each bedroom or sleeping

area—especially if bedroom or sleeping area doors are closed at night—and

in the hallway between them.
Smoke Alarms may not detect fire on another floor or area of the

dwelling. For example, a stand-alone unit on the second floor may not detect

smoke from a basement fire until the fire spreads. This may not give you

enough time to escape safely. That is why recommended minimum protection

is at least one unit in every sleeping area, and every bedroom on every level

of your dwelling. Even with a unit on every floor, stand-alone units may not

provide as much protection as interconnected units, especially if the fire starts

in a remote area. Some safety experts recommend installing interconnected

AC powered units with battery back-up (see “About Smoke Alarms”) or 

professional fire detection systems, so if one unit senses smoke, all units

alarm. Interconnected units may provide earlier warning than stand-alone 

units since all units alarm when one detects smoke.
Smoke Alarms may not be heard. Though the alarm horn in this unit meets

or exceeds current standards, it may not be heard if: 1) the unit is located 

outside a closed or partially closed door, 2) residents recently consumed

alcohol or drugs, 3) the Alarm is drowned out by noise from stereo, TV, traffic,

air conditioner or other appliances, 4) residents are hearing impaired or sound

sleepers. Special purpose units, like those with visual and audible alarms,

should be installed for hearing impaired residents.
Smoke Alarms may not have time to alarm before the fire itself causes

damage, injury, or death, since smoke from some fires may not reach 

the unit immediately. Examples of this include persons smoking in bed, 

children playing with matches, or fires caused by violent explosions

resulting from escaping gas.
Smoke Alarms are not foolproof. 
Like any electronic device, Smoke Alarms

are made of components that can wear out or fail at any time. You must test

the unit weekly to ensure your continued protection. Smoke Alarms cannot

prevent or extinguish fires. They are not a substitute for property or life 

insurance.
Smoke Alarms have a limited life. The unit should be replaced immediately 

if it is not operating properly. You should always replace a Smoke Alarm after

10 years from date of purchase. Write the purchase date on the space provided

on back of unit.

USING THE SILENCE FEATURE 

The Silence Feature can temporarily quiet an unwanted alarm for up to 15 

minutes.

The Silence Feature does not disable the unit—it makes it temporarily

less sensitive to smoke. For your safety, if smoke around the unit is dense

enough to suggest a potentially dangerous situation, the unit will stay in

alarm or may re-alarm quickly. If you do not know the source of the

smoke, do not assume it is an unwanted alarm. Not responding to an

alarm can result in property loss, injury, or death.
To silence Smoke Alarms in an interconnected series:
1. To silence multiple alarms in an interconnected series, you must press the

Test/Silence button on the unit(s) that triggered the alarm.

2. Once you activate the Silence feature, the Red LED will flash approximately

once every 10 seconds.

3. Pressing the Test/Silence button when in silence will restart the silence

timer.

The Silence Feature on these units can temporarily quiet an unwanted alarm for

up to 15 minutes. To use this feature, press the Test/Silence button on the cover.

If the unit will not silence and no heavy smoke is present, or if it stays in

silence mode continuously, it should be replaced immediately.

Model 3120B

with Battery Back-Up and Silence

AC Powered 

Photo & Ion Smoke Alarm

Input: 120V AC 

~

, 60Hz, 0.07A

Make sure the Alarm is not receiving excessively noisy power. Examples of noisy power could be major appliances on the same circuit, power from a

generator or solar power, light dimmer on the same circuit or mounted near fluorescent lighting. Excessively noisy power may cause damage to your

Alarm.

Low Battery

Alarm “chirp’’ approx.

once/minute

Alarm “chirp’’ approx.

once/minute

Low Battery Latch

Green LED flashing 2

seconds on, 

2 seconds off

Not available

LISTED TO

UL 217 

STANDARD

AGENCY PLACEMENT RECOMMENDATIONS

NFPA 72 (National Fire Code) Chapter 11
“For your information, the National Fire Protection Association's Standard 72,

reads as follows:”
“11.5.1 One- and Two-Family Dwelling Units.”
“11.5.1.1 Smoke Detection. 
Where required by applicable laws, codes, or 

standards for the specified occupancy, approved single- and multiple-station

Smoke Alarms shall be installed as follows: (1) In all sleeping rooms.

Exception: Smoke Alarms shall not be required in sleeping rooms in existing

one- and two-family dwelling units. (2) Outside of each separate sleeping area,

in immediate vicinity of the sleeping rooms. (3) On each level of the dwelling

unit, including basements. Exception: In existing one- and two family dwelling

units, approved Smoke Alarms powered by batteries are permitted.”
“A.11.8.3 Are More Smoke Alarms Desirable? The required number of

Smoke Alarms might not provide reliable early warning protection for those

areas separated by a door from the areas protected by the required Smoke

Alarms. For this reason, it is recommended that the householder consider 

the use of additional Smoke Alarms for those areas for increased protection.

The additional areas include the basement, bedrooms, dining room, furnace

room, utility room, and hallways not protected by the required Smoke Alarms.

The installation of Smoke Alarms in kitchens, unfinished attics, or garages 

is not normally recommended, as these locations occasionally experience

conditions that can result in improper operation.”

California State Fire Marshal (CSFM)

Early warning detection is best achieved by the installation of fire detection

equipment in all rooms and areas of the household as follows: A Smoke Alarm

installed in each separate sleeping area (in the vicinity, but outside bedrooms),

and Heat or Smoke Alarms in the living rooms, dining rooms, bedrooms,

kitchens, hallways, finished attics, furnace rooms, closets, utility and storage

rooms, basements, and attached garages.

LOCATIONS TO AVOID FOR SMOKE ALARMS

For best performance, AVOID installing Smoke Alarms in these areas:

Where combustion particles are produced. Combustion particles form

when something burns. Areas to avoid include poorly ventilated kitchens,

garages, and furnace rooms. Keep units at least 20 feet (6 meters) from

the sources of combustion particles (stove, furnace, water heater, space

heater) if possible. In areas where a 20-foot distance is not possible – in

modular, mobile, or smaller homes, for example – it is recommended 

the Smoke Alarm be placed as far from these fuel-burning sources as 

possible. The placement recommendations are intended to keep these

Alarms at a reasonable distance from a fuel-burning source, and thus

reduce “unwanted” alarms. Unwanted alarms can occur if a Smoke

Alarm is placed directly next to a fuel-burning source. Ventilate these

areas as much as possible.

In air streams near kitchens. Air currents can draw cooking smoke into

the sensing chamber of a Smoke Alarm near the kitchen.

In very damp, humid or steamy areas, or directly near bathrooms with

showers. Keep units at least 10 feet (3 meters) away from showers,

saunas, dishwashers, etc.

Where the temperatures are regularly below 40˚ F (4.4˚ C) or above 

100˚ F (37.8˚ C) including unheated buildings, outdoor rooms, porches, 

or unfinished attics or basements.

In very dusty, dirty, or greasy areas. Do not install a Smoke Alarm directly

over the stove or range. Clean a laundry room unit frequently to keep it

free of dust or lint.

Near fresh air vents, ceiling fans, or in very drafty areas. Drafts can blow

smoke away from the unit, preventing it from reaching sensing chamber.

In insect infested areas. Insects can clog openings to the sensing chamber

and cause unwanted alarms.

Less than 12 inches (305 mm) away from fluorescent lights. Electrical

“noise” can interfere with the sensor.

In “dead air” spaces. “Dead air” spaces may prevent smoke from reaching

the Smoke Alarm.

AVOIDING DEAD AIR SPACES

“Dead air” spaces may prevent smoke from reaching the Smoke Alarm. To

avoid dead air spaces, follow the installation recommendations below.
On ceilings, install Smoke Alarms as close to the center of the ceiling as 

possible. If this is not possible, install the Smoke Alarm at least 4 inches 

(102 mm) from the wall or corner.
For wall mounting (if allowed by building codes), the top edge of Smoke

Alarms should be placed between 4 inches (102 mm) and 12 inches (305 mm)

from the wall/ceiling line, below typical “dead air” spaces.
On a peaked, gabled, or cathedral ceiling, install the first Smoke Alarm 

within 3 feet (0.9 meters) of the peak of the ceiling, measured horizontally.

Additional Smoke Alarms may be required depending on the length, angle,

etc. of the ceiling's slope. Refer to NFPA 72 for details on requirements for

sloped or peaked ceilings.

SPECIAL COMPLIANCE CONSIDERATIONS

This Smoke Alarm alone is not a suitable substitute for complete fire

detection systems in places housing many people—like apartment 

buildings, condominiums, hotels, motels, dormitories, hospitals, long-

term health care facilities, nursing homes, day care facilities, or group

homes of any kind—even if they were once single-family homes. It is not

a suitable substitute for complete fire detection systems in warehouses,

industrial facilities, commercial buildings, and special-purpose non-resi-

dential buildings which require special fire detection and alarm systems.

Depending on the building codes in your area, this Smoke Alarm may be

used to provide additional protection in these facilities.
The following information applies to all four types of buildings listed below: 
In new construction, most building codes require the use of AC or AC/DC 

powered Smoke Alarms only. AC, AC/DC, or DC powered Smoke Alarms can be

used in existing construction as specified by local building codes. Refer to NFPA

72 (National Fire Alarm Code) and NFPA 101 (Life Safety Code), local building

codes, or consult your Fire Department for detailed fire protection requirements

in buildings not defined as “households.”
1. Single-Family Residence: 

Single family home, townhouse. It is recommended Smoke Alarms be installed

on every level of the home, in every bedroom, and in each bedroom hallway.
2. Multi-Family or Mixed Occupant Residence: 

Apartment building, condominium. This Smoke Alarm is suitable for use in

individual apartments or condos, provided a primary fire detection system

already exists to meet fire detection requirements in common areas like 

lobbies, hallways, or porches. Using this Smoke Alarm in common areas may

not provide sufficient warning to all residents or meet local fire protection 

ordinances/regulations.
3. Institutions: 

Hospitals, day care facilities, long-term health care facilities. This Smoke 

Alarm is suitable for use in individual patient sleeping/resident rooms, 

provided a primary fire detection system already exists to meet fire detection

requirements in common areas like lobbies, hallways, or porches. Using this

Smoke Alarm in common areas may not provide sufficient warning to all 

residents or meet local fire protection ordinances/regulations.
4. Hotels and Motels: 

Also boarding houses and dormitories. This Smoke Alarm is suitable for use

inside individual sleeping/resident rooms, provided a primary fire detection 

system already exists to meet fire detection requirements in common areas 

like lobbies, hallways, or porches. Using this Smoke Alarm in common areas

may not provide sufficient warning to all residents or meet local fire protection

ordinances/regulations.

ABOUT SMOKE ALARMS

Battery (DC) operated Smoke Alarms: Provide protection even when 

electricity fails, provided the batteries are fresh and correctly installed. Units

are easy to install, and do not require professional installation. They do not,

however, provide interconnected functionality.
AC powered Smoke Alarms: Can be interconnected so if one unit senses

smoke, all units alarm. They do not operate if electricity fails. 

AC with battery (DC) back-up: will operate if electricity fails, provided the

batteries are fresh and correctly installed. AC and AC/DC units must be

installed by a qualified electrician.
Wireless Interconnected Alarms: Offer the same interconnected functionality

as with hardwired alarms, without wires. Units are easy to install and do not

require professional installation. They provide protection even when electricity

fails, provided the batteries are fresh and correctly installed.
Smoke Alarms for Solar or Wind Energy users and battery backup power

systems: AC powered Smoke Alarms should only be operated with true or

pure sine wave inverters. Operating this Smoke Alarm with most battery-

powered UPS (uninterruptible power supply) products or square wave or

“quasi sine wave” inverters 

will damage the Alarm. If you are not sure about

your inverter or UPS type, please consult with the manufacturer to verify.
Smoke Alarms for the hearing impaired: Special purpose Smoke Alarms

should be installed for the hearing impaired. They include a visual alarm and

an audible alarm horn, and meet the requirements of the Americans With

Disabilities Act. These units can be interconnected so if one unit senses

smoke, all units alarm.

Continued...

ABOUT SMOKE ALARMS, Continued
Smoke alarms are not to be used with detector guards unless the 

combination has been evaluated and found suitable for that purpose.
All these Smoke Alarms are designed to provide early warning of fires if 

located, installed and cared for as described in the user’s manual, and if

smoke reaches the Alarm. If you are unsure which type of unit to install, refer

to NFPA (National Fire Protection Association) 72 (National Fire Alarm Code)

and NFPA 101 (Life Safety Code). National Fire Protection Association, One

Batterymarch Park, Quincy, MA 02269-9101. Local building codes may also

require specific units in new construction or in different areas of the home.

2

1

Choosing a replacement battery:
Your Smoke/CO Alarm requires two “AA” Energizer E91 batteries. 

These batteries are available at many local retail stores.

Actual battery service life depends on the Alarm and the environment in which

it is installed. All the batteries specified above are acceptable replacement

batteries for this unit. Regardless of the manufacturer’s suggested battery life,

you MUST replace the battery immediately once the unit starts “chirping”

(the “low battery warning”).
To replace the batteries (without removing Alarm from the ceiling or wall):
1. Open the battery compartment.
2. Press tabs A and B as shown in the diagram

and remove each battery.

3. Insert the new batteries, making sure 

they snap completely into the battery 

compartment. Match the terminals on the

ends of the batteries with the terminals on

the unit.

4. Close the battery compartment, and then

test the unit by pressing the Test/Silence 

button.

AB

SILENCING THE LOW BATTERY WARNING

This Silence Feature can temporarily quiet the low battery warning “chirp” for

up to 8 hours. Press the Test/Silence button on the Alarm cover until you hear

the acknowledge “chirp”.
Once the low battery warning “chirp” silence feature is activated, the unit

continues to flash the green light once a minute for approximately 8 hours.

After 8 hours, the low battery “chirp” will resume. The Alarm will continue 

to operate as long as AC power is supplied. However, 

replace the batteries

as soon as possible, to maintain protection in event of a power outage.
To silence Alarms in an interconnected series:

To silence an interconnected series of Smoke/CO Alarms, you must press the

Test/Silence button on the initiating alarm (The unit with the flashing red light;

the red light will be off on all other Alarms.). If you press the Test/Silence on

any other Alarm, it will only silence that unit, not the whole interconnected

series.

LATCHING FEATURE

Alarm Latch is activated after an Alarm is exposed to alarm levels of smoke.

This feature will only work with AC power. After smoke levels drop below alarm

levels, the

Red LED will begin flashing 2 seconds on, 2 seconds off unless

reset by test/silence button.
This feature helps emergency responders, investigators, or service 

technicians identify which unit(s) in your home were exposed to alarm levels

of smoke. This can help investigators pinpoint the source of smoke.
Interconnected Alarms. Latching Alarm Indicator shows which Alarm(s) in the

series were exposed to alarm levels of smoke. The Latching Alarm Indicator

stays ON until you clear it, so it can alert you to an alarm that occurred while

you were away from home, even though smoke present in the air has dropped

below alarm levels.
Low Battery Latch is activated when the Alarm is in the "low battery 

condition". When this occurs, the 

Green LED flashes 2 seconds on, 2 

seconds off. This feature is designed to help you identify which Alarm needs

to have the battery replaced. Although, the Alarm will sound the low battery

chirp approximately once every minute, sometimes during the initial stages 

of "low battery", the Alarm will chirp in greater intervals than one minute,

sometimes up to several hours, until the battery reaches a steady low battery

level. This innovative feature eliminates the frustration of waiting for and/or

identifying which unit is chirping.

“SMART INTERCONNECT” FEATURE

This Alarm includes "Smart Interconnect" which enables the Alarm to be

interconnected with other First Alert

®

and BRK Smoke, Heat, and "Smart

Interconnect" Smoke, Smoke/CO and CO Alarms. When smoke is detected,

all Alarms will sound the smoke horn pattern. When CO is detected, "Smart

Interconnect" Alarms will sound the CO horn pattern. Alarms that do not have

the "Smart Interconnect" feature will remain silent during a CO alarm.

Summary of Contents for 3120B

Page 1: ...heat or flame It cannot prevent or extinguish fires Understand The Different Type of Smoke Alarms Battery powered or electrical Different Smoke Alarms provide different types of protection See About S...

Page 2: ...nerally more sensitive than ionization technology at detecting large particles which tend to be produced in greater amounts by smoldering fires which may smolder for hours before bursting into flame S...

Page 3: ...d the alarm Latching Alarm Red LED flashing 2 seconds on 2 seconds off Not available AC Power DC Power Normal Operation Constant Green LED No Audible Alarm Flashing Green LED once minute No Audible Al...

Page 4: ...Smoke Alarms for details When the battery back up becomes weak the Smoke Alarm will chirp about once a minute the low battery warning This warning should last 7 days but you should replace the batter...

Page 5: ...on that requires your immediate attention NEVER ignore any alarm Ignoring the alarm may result in injury or death Never disconnect the AC power to quiet an unwanted alarm Disconnecting the power disab...

Page 6: ...Call the Fire Department as soon as possible from outside Give your address then your name Never go back inside a burning building for any reason Contact your Fire Department for ideas on making your...

Page 7: ...ns With Disabilities Act These units can be interconnected so if one unit senses smoke all units alarm Continued RECOMMENDED LOCATIONS FOR SMOKE ALARMS Installing Smoke Alarms in Single Family Residen...

Page 8: ...any component of the product found to be defective during the warranty period Replacement will be made with a new or remanufactured product or component If the product is no longer available replacem...

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