Bosch | 125 A | D125B Dual Class B Initiating Module

Fire Alarm Systems | D125B Dual Class B Initiating Module
D125B Dual Class B Initiating Module
Two separate powered detector loops
Suitable for 12 VDC or 24 VDC, two‑wire or
four‑wire detectors
Up to 50 two‑wire 12 VDC glass break detectors
Reports individual loop alarm, individual loop
trouble, and ground fault
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 twoor 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
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
When programming for fire applications, refer to the
appropriate control panel's operation and installation
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
• 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.
Do not mix 12 VDC and 24 VDC detectors on the
same D125B Module.
2 | D125B Dual Class B Initiating Module
24 VDC Applications
An auxiliary power supply is used in 24 VDC
applications. The auxiliary power supply provides
power for the module and all devices connected to the
two loops.
For a list of compatible two‑wire detectors, refer to the
D125B Installation Guide.
Small enclosure (gray)
Universal enclosure (gray)
Attack-resistant enclosure (gray)
Fire enclosure (red)
The power supply is not provided with the unit.
Any power supply installed must be UL listed for
use with Bosch fire products.
The D130 Relay Module is used for 24 VDC
applications. CMD 47 is used to reset 24 VDC smoke
detectors. Refer to the control panel's operation and
installation guide.
Unpowered initiating devices such as waterflow
switches, manual stations, and heat detectors are
installed without the D130 Relay Module.
Certifications and approvals
AMCX: Central Station Alarm Units
(UL1610, UL1635), AMCX7: Central
Station Alarm Units Certified for Canada
(ANSI/UL 1635), AOTX: Local Alarm
Units (UL464, UL609), S525), APAW:
Police Station Alarm Units (UL365,
UL464), APAW7: Police-station-connected Alarm Units Certified for Canada
(CAN/ULC -S303, CAN/ULC-S304,
CAN/ULC-S525), APOU: Proprietary
Alarm Units (UL1076), NBSX: Household Burglar Alarm System Units
(UL1023), UOJZ: Control Units, System
(UL864, 9th edition), UTOU: Control
Units and Accessories - Household System Type (UL985)
see our website
#6174 UL 864 9th Edition
12-92-E, Vol. XV
For a list of compatible modules, refer to the D125B
Installation Guide.
G-series = D9412GV4, D7412GV4, D7212GV4*, D9412GV3,
D7412GV3, D7212GV3*, D9412GV2, D7412GV2, D7212GV2*,
D9412G3, D7412G3, D7212G3*
B‑series = B5512 and B4512
These products are legacy products and have been investigated for
compatibility only to UL864 8th edition.
The D7212 models are not listed for commercial fire applications.
Mounting Considerations
The D125B module mounts in the Bosch control panel
enclosure using screws included with the unit. Use a
D137 Mounting Bracket to install additional modules
in the same enclosure, or when installing the D125B in
an approved adjacent enclosure. Separate enclosures
must be within 20 ft (6.1 m) of the control panel
enclosure and connected by conduit.
Wiring Considerations
When used in a fire system, NFPA 72 prohibits this
product from sharing a communications bus with
non-fire devices.
The D125B needs to be electrically connected to the
control panel's common terminal.
Parts included
D125B module
Installation/configuration notes
1.8 kΩ EOL resistors (P/N: F01U009011)
Compatible Products
The following products are compatible with the D125B
Dual Class B Initiating Module:
Hardware pack
Literature pack
Product ID
Product Description
Control panels
Control panels
Control panels
Control panels
Control panel
Technical specifications
Mechanical Properties
(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):
1 loop only:
75 mA maximum
Both loops:
145 mA maximum
1 loop only:
12 mA maximum
3 | D125B Dual Class B Initiating Module
Both loops:
Voltage (nominal)
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:
168 mA maximum
Both loops:
300 mA maximum
1 loop only:
25 mA maximum
Both loops:
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
24 VDC:
7 mA maximum
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
D137 Mounting Bracket
Used to mount accessory modules in D8103, D8108A,
and D8109 enclosures.
Order number D137
Represented by:
Bosch Security Systems, Inc.
130 Perinton Parkway
Fairport, New York, 14450, USA
Phone: +1 800 289 0096
Fax: +1 585 223 9180
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
© Bosch Security Systems 2014 | Data subject to change without notice
2691432971 | en, V3, 17. Jul 2014
Robert Bosch (SEA) Pte Ltd, Security
11 Bishan Street 21
Singapore 573943
Phone: +65 6571 2808
Fax: +65 6571 2699
America Latina:
Bosch (Shanghai) Security Systems Ltd. Robert Bosch Ltda Security Systems Division
201 Building, No. 333 Fuquan Road
Via Anhanguera, Km 98
North IBP
CEP 13065-900
Changning District, Shanghai
Campinas, Sao Paulo, Brazil
200335 China
Phone: +55 19 2103 2860
Phone +86 21 22181111
Fax: +55 19 2103 2862
Fax: +86 21 22182398
Download PDF