Context Plus Common Base, 45681-200 The Context Plus Common Base is designed to accept DIL switch addressed smoke Optical and
Temperature detectors. Polarity must be observed as indicated. A self adhesive label is provided with each base to mark the detector address.

If you require remote LED indication, an additional remote LED driver PCB assembly must be used, part no. 43781-089 (driver fits in base) Context Plus Negative Switching Isolating Base, 45681-505IMC Designed to sense and isolate short-circuits on Context Plus loops, the Context Plus Negative Switching Isolating base can be used in place of standard bases.

Under normal operating conditions the isolating circuit provides a low resistance of 0.2 ohm in either direction. If the loop voltage falls to 14±0.4V the isolator will switch from the closed state to the open state in order to isolate the loop ‘in’ and ‘out’ lines. The isolated section is tested every four seconds and is automatically re- connected when the load resistance is 175 or greater.

The current pulses are drawn from the loop and it is important for correct operation of the system that the pulse load be included in the loop calculation made for any system. Up to 20 detectors or the equivalent load may be connected between two isolating circuits. Interfaces and sounders are counted as one detector for every milliampere of switch-on surge current.

Isolating bases are loop powered and polarity sensitive and can be damaged if connected in reverse polarity. It is important to note the polarity is indicated at the wiring terminal. All wiring terminals will accept solid or stranded cables up to 2.5mm2. A Yellow LED illuminates if a short-circuit is detected either side of the isolator. Complies with EN54-17 (2005).