How to Install a Portable Generator Transfer Switch

  • 2-4 hours
  • Advanced
  • 250-500
What You'll Need
Extension cord
Breaker box
Transfer switch panel
10/4 cable
New breakers

A portable generator transfer switch will transfer power to selected circuits in the event of a power outage. Once installed, you’ll simply need to plug in your portable generator and crank it up. Everything in the new circuit box, or portable generator transfer switch, will run. For anyone used to working with electricity, this isn’t a complex task. However, novices should get experienced help before attempting to install a portable generator transfer switch because of the potential dangers involved in working with electricity. Here are the steps to install your new portable generator transfer switch.

Step 1 - Buy a Generator

Before installing a portable generator transfer switch you need to know what size generator to buy. How much do you really need to run during a power outage? Look at the wattage of the appliances and buy a generator that allows for a comfortable margin above this to accommodate for spikes in energy consumption.

Step 2 - Shut Off Power

Shut off power to the main breaker box and take off the cover. Remember that the main disconnect terminal will still be hot so avoid approaching it. You’ll see a circle in the side of the box. Knock this out and put in a threaded nipple. At the other end of the nipple attach the new box. Use heavy screws to anchor the new box to the wall next to your main circuit panel. Now attach the grounding bus to the wall of the new panel.

Step 3 - Wire It

Man working on electrical panel

You may need to focus on selecting specific circuits that you would need during an outage such as lighting, water pump, and appliances. The goal is to attach wiring from the transfer switch to the existing wires so power can alternate between either one as needed.

Remove the black wire from each of the breakers which have a circuit you want to power with the generator. Use an insulated screwdriver for this. Remove the breaker from the panel and remove the white and green wires. Tape all three wires for each circuit together. Strip the sheathing from 10/4 cable and feed it through the conduit between the two boxes. Connect the white and green wires to the appropriate buses in the main panel. Now attach the red and black wires from the 10/4 cable to a breaker that’s 30 amps and 240 volts and press it into place in the main panel. Repeat the connections in the transfer panel switch panel. Once you have the hot wires connected to a breaker and installed you have power to the side panel.

Step 4 - Extend the Wires

You’ll need to extend the wires from the circuits you’ve disconnected to bring them into the portable generator transfer switch panel. Depending on the local code, you might be able to use wire connectors for this purpose. Having done this, bring the wires through the conduit. Attach the white wire to the neutral bus, the green wire to the ground bus, and the black wire to the breaker.

Step 5 - Setup Outlets

wires coming through a wall

To set up an outlet for the portable generator to plug into within the power generator transfer switch, you’ll need more 10/4 cable. Install your outlet outside the house, on the wall outside your electrical control panel. Mount it to the house and drill a hole through the side of the house to run the wiring to the inside. Connect to the receptacle for the generator. In the breaker box attach the white and green wires to their respective buses and attach the black wire to a free 240-volt breaker.

Test your newly install transfer switch by turning off the main circuit breaker and turning on the breakers to the portable generator. Plug in the generator and run it to ensure power is working properly.