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B501 Plug-in Detector Base

INSTALLATION AND MAINTENANCE INSTRUCTIONS

3825 Ohio Avenue, St. Charles, Illinois 60174

1-800-SENSOR2, FAX: 630-377-6495

www.systemsensor.com

BEFORE INSTALLING 

Please read the 

System Smoke Detectors Application Guide

, which provides 

detailed information on detector spacing, placement, zoning, wiring, and spe-
cial applications. Copies of this application guide are available from System 
Sensor. NFPA 72 guidelines should be observed.

NOTICE

: This manual should be left with the owner/user of this equipment.

IMPORTANT

: The detector used with this base must be tested and maintained 

regularly following NFPA 72 requirements. The detector should be cleaned at 
least once a year.

GENERAL DESCRIPTION

The B501 is a plug in detector base intended for use in an intelligent system 
with screw terminals provided for power (+) and (–), and remote annuncia-
tor connections. Communication takes place over the power (+) and (–) lines. 

BASE TERMINALS

No. 

  Function

 

 

Power (–), Remote Annunciator (–)

2    Power 

(+)

 

 

Remote Annunciator (+)

FIGURE 1. TERMINAL LAYOUT:

TAMPER PROOF

TAB

TERMINAL 3 

TERMINAL 2 

TERMINAL 1 

MOUNTING

This detector base mounts directly to 4 inch square with plaster ring, 3.5 inch 
octagon, 50 mm, 60 mm, and 70 mm centers.

INSTALLATION AND WIRING GUIDELINES (SEE FIGURE 2)

All wiring must be installed in compliance with all applicable local codes 
and any special requirements of the local authority having jurisdiction. Proper 
wire gauges should be used. The conductors used to connect smoke detectors 
to control panels and accessory devices should be color-coded to reduce the 
likelihood of  wiring errors. Improper connections can prevent a system from 
responding properly in the event of a fire.

SPECIFICATIONS

Base Diameter: 

4.0 inches (10.2cm)

Base Height: 

.74 inches (18.8 mm) 

Operating Temperature: 

Refer to applicable sensor Operating Temperature Range using the Base/Sensor Cross Reference Chart at systemsensor.com

Electrical Ratings – includes base and detector

Operating Voltage: 

15 to 32 VDC

Standby Current: 

150µA

I56-3738-00

2R

For signal wiring (the wiring between interconnected detectors and modules), 
it is recommended that the wiring be no smaller than 18 AWG (0.823 square 
mm). Wire sizes up to 12 AWG (3.31 square mm) may be used with the base. 

Alarm system control panels have specifications for allowable loop resistance. 
Consult the control panel specifications for the total loop resistance allowed 
before wiring the detector loops. 

Make wiring connections by stripping about 

3

8

 inch (10 mm) of insulation 

from the wire end (use strip gauge molded in base). Then slide the wire under 
the clamping plate and tighten the clamping plate screw. Do not loop the wire 
under the clamping plate. (see Figure 3)

Check the zone wiring of all bases in the system before installing the detec-
tors. This includes checking the wiring for continuity, correct polarity, ground 
fault testing and performing a dielectric test. 

The base includes an area for recording the zone, address, and type of detec-
tor to be installed at that location. This information is useful for setting the  
detector head address and for verification of the detector type required for 
that location.

Once all detector bases have been wired and mounted, and the loop wiring 
has been checked, the detector heads may be installed in the bases.

FIGURE 2. TYPICAL WIRING DIAGRAM FOR 2-WIRE LOOP:

(–)

(+)

+

-

UL

 LISTED COM

PA

TIBLE

CONTROL

 P

ANEL

CAUTION: DO NOT LOOP WIRE 

UNDER TERMINAL 1 OR 2.

BREAK WIRE RUN TO PROVIDE 

SUPERVISION OF CONNECTIONS.

CLASS A OPTIONAL WIRING

REMOTE 

ANNUNCIATOR

(–)
(+)

3

2

1

3

2

1

3

2

1

FIGURE 3.:

C0473-00

C0131-01

C0133-01

  

I56-3738-002R 

 

 03-11

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