The GTDU generator transfer device works in conjunction with an auxiliary generator or a central inverter system to power existing incandescent, fluorescent or LED fixtures for egress lighting regardless of fixture wall switch position or dimsetting. The device consists of relay switching circuitry in 1-compact steel case. 1-generator transfer device per fixture is used to bypass the fixture wall switch and/or dimmer, allowing the building's generator (or central inverter) to operate switchable fixtures at full illumination. The generator transfer device is suitable for indoor or damp locations and for sealed and gasketed fixtures. Recommended applications include: auditoriums, classrooms, hospital, offices or any other location with generator (or central inverter) supplied lighting.