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B224BI-WH, B224BI-IV  

Plug-in Isolator Detector Base 

INSTALLATION AND MAINTENANCE INSTRUCTIONS

BEFORE INSTALLING

Please read the 

System Smoke Detector Applications Guide

, which provides 

detailed information on detector spacing, placement, zoning, wiring, and spe-
cial applications. This manual is available online at www.systemsensor.com. 
NFPA 72 guidelines should be observed.

NOTICE:

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

IMPORTANT:

 The detectors used with these bases must be tested and main-

tained following NFPA 72 requirements. The detectors used with these bases 
should be cleaned at least once a year.

GENERAL INFORMATION

The B224BI-WH and B224BI-IV isolator bases intended for use in an intelli-
gent system. Isolator bases prevent an entire communications loop from being 
disabled when a short circuit occurs. They accomplish this by isolating that 
part of the loop containing the short from the remainder of the circuit. These 
bases also automatically restore the entire loop when the cause of the short 
circuit is corrected. In general, up to 25 addressable devices may be isolated 
between isolator bases.

MOUNTING

Mount the mounting plate directly to an electrical box. The plate will 
mount directly to 4" square (with and without plaster ring), 4" octagon,  
3

1

/

2

" octagon, single gang and double gang junction boxes.

1. Connect field wiring to terminals, as shown in Figure 3 and 4.
2. Attach the mounting plate to the junction box as shown in Figure 2.
3.  To mount the base, hook the tab on the base to the groove on the mounting plate.

SPECIFICATIONS

Base Diameter: 

6.85 in (17.4 cm)

Base Height: 

1.61 in (4.1 cm)

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

10% to 93% Relative Humidity (Non-condensing)

Electrical Ratings

Operating Voltage: 

15 to 32 VDC

Standby Current: 

450 µA Maximum

Isolation Current: 

15 mA Maximum

I56-3736-00

5

3825 Ohio Avenue, St. Charles, Illinois 60174

1.800.SENSOR2; Fax: 630.377.6495

www.systemsensor.com

4.  Then, swing the base into position to engage the pins on the product with 

the terminals on the mounting plate.

5. Secure the base by tightening the mounting screws.
6.  Install a compatible smoke detector as described in the installation manual 

for the detector.

CAUTION

Do not over tighten mounting plate screws; this may cause mounting plate 
to flex.

INSTALLATION GUIDELINES

All wiring must be installed in compliance with all applicable local codes and 
any special requirements of the local authority having jurisdiction, using the 
proper wire sizes. 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.
For signal wiring (the wiring between interconnected detectors), it is recom-
mended that the wire be no smaller than 18 AWG (0.823 mm

2

). However, wire 

sizes up to 12 AWG (3.31 mm

2

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

FIGURE 3.

LISTED COM

PA

TIBLE CONTRO

PA

NE

L

CLASS A OPTIONAL WIRING

(+)

(–)

(+)

(–)

2 - COMM IN (–)

1 - COMM IN (+) 

3 - COMM OUT (+)

2 - COMM OUT (–)

OTHER 

INTELLIGENT

DEVICES

C1003-01

FIGURE 1.  

TERMINAL DESIGNATION

1

2

3

 

C0471-05

B224BI-WH/B224BI-IV 

TERMINALS

No. Function
1.   Positive (+) Comm. Line In
2.    

Negative (–) Comm. Line In 
and Out

3.   Positive (+) Comm. Line Out

FIGURE 2. MOUNTING BASE TO 

ELECTRICAL BOX

MOUNTING 

PLATE

BOX

(NOT SUPPLIED)

SCREWS

(NOT SUPPLIED)

C1008-01

  

I56-3736-005 

 

 02/01/2018

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