How to Wire a 12 Volt Electrical Relay

By Joey Butler

An electrical relay can be used to control a device remotely with a switch designed for less of a load than the device being switched. Relays can even be used for building simple logic into electrical circuits, according to Glen Baxter, a certified electrician. A 12-volt relay is perfect for controlling electrical devices in an auto, a tractor or 12-volt systems in campers; in addition, says Baxter, 12-volt relays are readily available and easy to wire.

Things You'll Need

  • 12-volt relay
  • 6 wires
  • Switch
  • Power supply

Step 1

Connect the end of a wire to one side of a switch. Connect the other end of the same wire to the positive terminal on your power supply.

Step 2

Connect the end of a wire to the other side of your switch. Connect the other end of the same wire to one of the coil terminals on the relay. The coil terminals should be marked on the relay, but sometimes the terminals will be numbered. Consult the relay wiring diagram from the manufacturer if the terminals are numbered.

Step 3

Attach the end of a wire to the other coil terminal. Connect the other end of the same wire to the neutral side of your power supply.

Step 4

Connect the end of a wire to one of the load terminals on the relay. Connect the other end of the same wire to the positive terminal on your power supply.

Step 5

Finish the circuit by connecting the end of a wire to the other load terminal on the relay and the other end of the same wire to one side of the load device. Attach a wire to the other side of the load device and connect the other end of the same wire to the neutral terminal on your power supply.

Step 6

Turn the switch to the "on" position and test your circuit.