The D125B has two separate NFPA Class 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.
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 installing a D125B in a new system or are adding additional devices to an existing system, use the 1.8 kΩ resistor (P/N: F01U009011) supplied with the module.
