How to wire AC contactor lighting

Written by william pippin
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Alternating current contactors for lighting are generally used on large amperage --- 30 amps or more --- lighting circuits that run on 220 volts. The contactors are controlled by a separate 110-volt input, usually a single-pole switch or a photocell. Using a contactor prevents the need for using an expensive 30-amp, two-pole switch to control the lights; it also allows you to control the lights remotely with a photocell or home automation system.

Skill level:

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Things you need

  • Straight screwdriver
  • Wire strippers
  • Wire nut

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  1. 1

    Identify the "L1" and "L2" terminals marked on the contactors. These are your input lines for both hot black wires feeding the circuit.

  2. 2

    Insert the two hot wires coming from the electrical panel into the L1 and L2 terminals and tighten with your straight screwdriver. Attach both bare grounding wires together along with another 6-inch piece of ground wire with a wire nut. Curl the end of the extra wire with your strippers. Insert the curled end of the bare wire under the green grounding screw in the contactors' box and tighten the screw.

  3. 3

    Identify the two terminals on the contactors marked "T1" and "T2." These are your load connections. Insert the two black hot wires that go to the lights to these terminals and tighten the screws.

  4. 4

    Connect the white neutral wire from the control switch to the "L" on the contactors' control input. Connect the black hot wire or switch leg to the "NO" connection on the contactors. By connecting your control wire up to the "NO" connection terminal, the lights are normally off but when a voltage is applied from the switch the contactors close and complete the circuit and the lights come on.

Tips and warnings

  • There are several different types of contactors. Many have built in controls for turning the lights on and off, whether it be a remote module for using a remote control switch. Thermal couplers are used for automatically turning the contactors on or off by temperature. Photocell modules can automatically turn the lights on and off by sensing the light from the sun during the day and lack of it at night. Any lighting contactor with these modules built in won't necessarily require control wires to be hooked up to the contactors as they are controlled by the built-in control circuits.
  • Always disconnect power to any device or circuit you plan on working on to prevent shock or electrocution.

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