First Alert 9120 Series User Manual Download Page 4

OPTIONAL LOCKING FEATURES

The optional locking features are designed to discourage unauthorized removal of the battery 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.

Locking Pin

TO LOCK THE BATTERY COMPARTMENT

(Model 9120B Only)

Do not lock the battery compartment until you have activated 
the battery and tested the battery back-up.

1. Activate the battery back-up by removing

the “Pull to Activate Battery Back-Up” tab.

2. Push and hold test button until the alarm

sounds: 3 beeps, pause, 3 beeps, pause.

If the unit does not alarm during testing,
DO NOT lock the battery compartment!
Install a new battery and test again. 
If the Smoke Alarm still does not alarm,
replace it immediately.

3. Using needle-nose pliers or a utility 

knife, detach one locking pin from 
the mounting bracket.

TO UNLOCK THE BATTERY COMPARTMENT

(Model 9120B Only)

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 battery from Smoke Alarms with battery back-up.
Finally, press and hold the test 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 bat-
tery 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 battery, 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 battery from Smoke Alarms with battery back-up.
Finally, press and hold the test 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 screw-

driver and the Smoke Alarm counterclockwise (left) at the same time.

TO LOCK THE MOUNTING BRACKET

1. Using needle-nose pliers or utility

knife, detach one locking pin from
mounting bracket.

2. Insert the locking pin into the 

lock located on the base 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.

4. Push the locking pin through the

black dot on the label on the back
of the Smoke Alarm.

4

Summary of Contents for 9120 Series

Page 1: ...er 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 o...

Page 2: ...stall 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 210 760 of NFPA 70 NEC NFPA 72 NFPA 101 ICC 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 t...

Page 3: ...tarts 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 Green LED s On for 2 seconds Off for 2 seconds On All Other Alarms Green LED s On Red LED ...

Page 4: ...vicing an AC or AC DC Smoke Alarm First turn off the AC power at the circuit breaker or fuse box Next remove the battery from Smoke Alarms with battery back up Finally press and hold the test 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 ...

Page 5: ... alarm will reset auto matically 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 I...

Page 6: ...s from the sources of combustion particles stove furnace water heater space heater if possible In areas where a 20 foot 6 meter 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 burn...

Page 7: ... not provide sufficient warning to all residents or meet local fire protection ordinances regulations 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 alarm...

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