Abstract: A control unit for switching AC powered high efficiency lighting in response to a signal from an occupancy sensor. The lighting is switched by a hybrid mechanical relay/semiconductor switch. The semiconductor switch is connected in parallel with the relay switch contacts to protect them and is controlled by a noise-insensitive zero voltage crossing detector circuit which switches the semiconductor switch only at the zero crossings of the AC power. The semiconductor switch is preferably turned on by a pulse forming circuit only for a brief period of time spanning the time when the relay is switching.