How to Wire a 480-Volt 3-Wire With Ground

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480-volt powers large equipment in factories.

Factories and other industrial buildings sometimes require a higher voltage for their electrical service. This is especially true if it's a factory that uses large electrical motors that run off 480-volt electrical service. Knowing how to wire a 480-volt plug to the motor is essential to ensure you do not electrocute yourself or cause a fire. While working with 480-volt electricity can seem intimidating, it can be a safe and easy process if you follow the proper procedures.


Step 1

Turn off the circuit breaker to the 480-volt outlet you will be plugging your machine into. Even though you will be working on the unplugged machine with no power, it is best to have the power off to avoid any risk of electrocution when plugging into the outlet.

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Step 2

Use a screwdriver to remove the electrical panel on the back of the machinery you want to install the electrical plug on.


Step 3

Loosen the four screws inside the electrical panel.

Step 4

Push in the three black wires from the electrical plug into each of the golden or silver colored screws. Secure the wires in place by tightening down with the screwdriver. Do not plug the black wires into the green screw.


Step 5

Connect the green wire from the electrical plug to the green screw inside the electrical panel. Secure the wire in place with the screwdriver.

Step 6

Place the electrical cover back on the machine and secure it in place with the screwdriver.


Step 7

Push in the electrical plug into the 480-volt outlet until it is in all the way.

Step 8

Turn on the circuit breaker and test the machine. If the machine does not turn on, disconnect it and check for any loose wires.


Make sure the machine requires a 480-volt plug. Some machinery run off 220-volt and will burn out if plugged to a 480-volt power source.


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