A high-voltage lighting system, such as ballroom lighting in a high-end home, must provide a way to energise the light bulbs without jeopardising the operator. Lighting contactors provide a way to activate the lights from a remote location like a wall switch. When electricity from the switch enters the contactor's low-voltage circuit, an electromagnet closes the contact points of the contactor's high-voltage circuit. This allows the high-voltage electricity to pass through the contactor to the lighting system. A contactor's points open when the low-voltage power source disconnects. A contactor's design prevents electricity from arcing while the contact points are open.
Locate and turn the circuit breaker labelled "Lighting" off. Lighting systems that use contactors operate with high voltage, often 220 volt.
Open the lighting system's service box. Usually located near the lights, it has three sets of wires leading to it: One wire set leads to the switch; one set leads to the circuit breaker, and one set leads to the lights. The box also contains a step-down transformer with clearly marked high-voltage (primary) and low-voltage (secondary) wires.
Mount the contactor to the electrical service box's housing with the hex-head screws included with the electrical box. Push the screws through the contactor's mounting holes, located near the contactor's edge, into the electrical box's pre-drilled holes, and tighten the screws with the correct-sized screwdriver.
Loosen the contactor's terminal screws with a slotted screwdriver. A 220-volt lighting contactor contains six terminal screws: two low-voltage (control); two high-voltage input (Line), and two high-voltage output(Load). The Line and Load terminal sets both contain "L1" and "L2" terminals. A label, usually moulded into the contactor's housing, identifies each terminal.
Push the wire from the low-voltage side of the transformer into one of the contactor's low-voltage terminals, and tighten the terminal screw with a slotted screwdriver. The transformer's other low-voltage wire connects to one of the wires that leads to the switch.
Push the remaining wire from the switch into the contactor's remaining low-voltage terminal, and tighten the screw with the slotted screwdriver. This completes the low-voltage circuit: Power flows from the transformer to the switch, then from the switch to the contactor, and from the contactor back to the transformer.
Push the wire set from the circuit breaker into the contactor's Line terminals. Push the neutral wire--usually the wire with white-coloured insulation--and one of the transformer's high-voltage wires into the L1 terminal. Push the hot wire--usually the wire with black-coloured insulation--and the transformer's other high-voltage wire into the L2 terminal. Tighten the terminal screws with the slotted screwdriver.
Push the wire set that leads to the light into the contactor's Load terminals. Push the neutral wire--usually the wire with white-coloured insulation--into the L1 terminal, and the hot wire--usually the wire with black-coloured insulation--into the L2 terminal. Tighten the terminal screws with the slotted screwdriver.
Close the electrical box's lid, and test the lighting system.