Fire Alarm Systems | D125B Dual Class B Initiating Module
D125B Dual Class B Initiating Module
u Two separate powered detector loops
u Suitable for 12 VDC or 24 VDC, two‑wire or
four‑wire detectors
u Up to 50 two‑wire 12 VDC glass break detectors
u Reports individual loop alarm, individual loop
trouble, and ground fault
u Manually resets latching devices from control panel
or remote central station
The D125B has two separate NFPA Class B (Style B)
powered loops. The module supervises each of the
loops for opens, shorts, or ground faults. Both loops
can be powered with either 12 VDC or 24 VDC to
connect compatible two-wire detectors or other two-
or four-wire devices such as retarded waterflow
switches, manual stations, heat detectors, or glass
break detectors.
The D125B is suitable for connecting fire or burglary
devices in commercial, industrial, and institutional
applications. Schools, offices, and health care facilities
are typical commercial applications.
adding additional devices to an existing system, use
the 1.8 kΩ resistor (P/N: F01U009011) supplied with
the module.
The D125B shorts the protective loop on the control
panel when the high (+) and low (-) side of either
module loop is shorted together or when a smoke
detector activates. The D125B opens the protective
loop on the control panel during the following
conditions:
• Either of the module protective loops are opened.
• The D125B Interface module is unpowered.
• Either the high (+) side of the loop or the low (-) side
of the loop is shorted to ground.
Functions
With the D9412GV3, D7412GV3, D7212GV3,
D9412GV2, D7412GV2, D7212GV2, D9412G, D7412G,
and D7212G Control Panels, a short to ground causes
a ground fault condition when ground fault detect is
enabled.
When programming for fire applications, refer to the
appropriate control panel's operation and installation
guide.
Loop Supervision
The D125B needs to be electrically connected to earth
ground and to the control panel's common. The D125B
has a supervisory output terminal for each of its loops.
All terminal designations are clearly marked on the
module circuit board.
To supervise the loops, install an end-of-line (EOL)
resistor beyond the last detector of each protective
loop. If you are replacing a D125 or D125A Module
with the D125B, use the 1.5 kΩ resistor
(P/N: 15-03130-000) installed with the original system.
If you are installing a D125B in a new system or are
Notice
Do not mix 12 VDC and 24 VDC detectors on the
same D125B Module.
3 | D125B Dual Class B Initiating Module
Technical specifications
Mechanical Properties
Dimensions
(H x W x D):
5 in. x 3 in. x 0.8 in.
(12.7 cm x 7.6 cm x 2.0 cm)
Power Requirements (12 VDC Circuits)
Current (alarm):
Current (standby):
Voltage (nominal)
1 loop only:
Both loops:
1 loop only:
Both loops:
75 mA maximum
145 mA maximum
12 mA maximum
24 mA maximum
12 VDC supplied by control panel or by
UL864 or UL1481 Listed 12 V power supply
Power Requirements (24 VDC Circuits)
Current (alarm):
Current (standby):
Voltage (nominal)
1 loop only:
Both loops:
1 loop only:
Both loops:
168 mA maximum
300 mA maximum
25 mA maximum
50 mA maximum
24 VDC supplied by UL864 or UL1481
Listed 24 V power supply
Two-wire Loop (Class B, Style B)_Characteristics
Current (alarm):
Current (trouble):
Detector Current:
Wiring Impedance:
12 VDC:
>11.8 mA
24 VDC:
>24.1 mA
12 VDC:
<3.5 mA
24 VDC:
<7.5 mA
12 VDC:
3 mA maximum
7 mA maximum
24 VDC:
50 Ω maximum
Ordering information
D125B Dual Class B Initiating Module
The module provides 2 Class B (Style B) powered
loops for connecting 12 or 24 VDC, two- or four‑wire
fire or burglary devices or up to 50 two‑wire 12 VDC
glass break detectors. It reports individual loop alarm
or trouble and ground fault; and allows latching device
reset from panel or central station.
Order number D125B
Accessories
D137 Mounting Bracket
Used to mount accessory modules in D8103, D8108A,
and D8109 enclosures.
Order number D137
4 | D125B Dual Class B Initiating Module
Represented by:
Americas:
Europe, Middle East, Africa:
Bosch Security Systems B.V.
P.O. Box 80002
5617 BA Eindhoven, The Netherlands
Phone: + 31 40 2577 284
Fax: +31 40 2577 330
Asia-Pacific:
Robert Bosch (SEA) Pte Ltd, Security
Systems
11 Bishan Street 21
Singapore 573943
Phone: +65 6571 2808
Fax: +65 6571 2699
China:
America Latina:
Bosch Security Systems, Inc.
130 Perinton Parkway
Fairport, New York, 14450, USA
Phone: +1 800 289 0096
Fax: +1 585 223 9180
Bosch (Shanghai) Security Systems Ltd. Robert Bosch Ltda Security Systems Division
201 Building, No. 333 Fuquan Road
North IBP
Changning District, Shanghai
200335 China
Phone +86 21 22181111
Fax: +86 21 22182398
Via Anhanguera, Km 98
CEP 13065-900
Campinas, Sao Paulo, Brazil
Phone: +55 19 2103 2860
Fax: +55 19 2103 2862
© Bosch Security Systems 2013 | Data subject to change without notice
2691432971 | en, V2, 06. Aug 2013
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