The key lock switch is used to control the power supply of a room. It has a built- in indicator which is ON when no key is in the device so we can find the device in a dark room. The consumption of the indicators is very small. The GR-48 model can be fitted on regular wall outlet mountings. The figure below shows the connection of the device for max. power of 1500W and the connection of the device for output power greater than 1500W.