By Joseph Elmadam, Updated Mar 24, 2022
Lighting contactors are relay switches that control the flow of electricity through a circuit powering the lighting in a given area. They are located remotely and control circuits with higher voltages, which can be dangerous to the operator if handled directly. A lighting contactor switch operates at a lower, safer load and uses an electromagnet to control the high‑voltage/current circuit.
Turn the power off for the entire system by switching off the main circuit breaker. Wear electrical gloves and take all necessary safety precautions, as lighting circuits carry heavy electrical loads.
Locate and open the service box that feeds power to the lights. This box, typically situated near the lighting fixtures, contains the transformer and the wiring that connects the lights to their switches and the circuit breaker. Mount the contactor in the service box using a screwdriver and secure it with screws.
Loosen the terminal screws on the contactor. Lighting contactors have six terminals: two for low‑voltage control and four for high‑voltage operation. The low‑voltage terminals are called “control” terminals, the high‑voltage input terminals are “line,” and the high‑voltage output terminals are “load.”
Connect the switch wire to one of the low‑voltage terminals on the transformer. Run a second wire from the transformer’s other low‑voltage terminal to a control terminal on the contactor. Connect the second switch wire to the remaining control terminal on the contactor.
Insert the neutral wire from the circuit breaker and one of the high‑voltage wires from the transformer into the contactor’s line terminal marked “L1.” Place the live (hot) wire from the circuit breaker and the other high‑voltage transformer wire into the line terminal marked “L2.” (Live wires are typically black or red; neutral wires are white.)
Wire the neutral wire that supplies the lights to the contactor’s load terminal marked “L1,” and wire the live/hot wire to the terminal marked “L2.” After verifying all connections, close the service box.
