A power supply assembly for a lighting system is directly mountable onto a standard electrical junction box. The power supply circuit provides an electronically power limited output through multi-conductor power connectors. The power supply assembly is used as part of a lighting system. The power supply output is used to connect to luminaires using a multi-conductor cable having multi-conductor power connectors which mate with the multi-conductor power connectors on the power supply and luminaire. The luminaires use a circuit to interface between the power supply output and the lamp.