The GS100M is a wall or panel mounted microprocessor based gas detector control. It can be configured to meet customer requirements. The GS100M has two plug in terminal blocks. One is for the incoming mains supply and alarm circuit wiring and the second is for connecting the sensor wiring. This reduces the chance of incorrect site wiring. The printed circuit board has an overload light which indicates when a short circuit or an overload has occurred on the sensor wiring.