How to Install a Transfer Switch

High voltage home repair

A transfer switch, along with a generator, provides an important line of defense in preventing loss of life or property during a power outage. The transfer switch acts as a means to keep the generator and the primary power source (usually mains electricity from the residential power grid) from conflicting. The mechanism functions like a double throw switch, where only one means of providing energy can be active at a time: either the generator or the primary power source.

Transfer switches assure the safety of lineman who might be working with the lines (particularly in the case of a power outage) and secondarily, the home generator. A properly installed transfer switch prevents electricity generated in a private home from sneaking through the house’s supply lines back out into the grid. The transfer switch also protects the generator from a harmful backfeed, which could destroy the unit or any transformer serving the house.

Although simple and inexpensive, a transfer switch serves a vital function. If you own a generator to power your home during an outage, a transfer switch allows your home power distribution system to accept the correct input. These devices safely connect generators to load centers in homes to power a set number of devices.

Steps to correctly configure a transfer switch

1.  Determine the appliances, circuits or equipment you want to operate with generator power during a power outage, such as lights, climate control, refrigeration, and heating. Correctly mapping which appliances will work on which circuit assures no one circuit will be overburdened and therefore prone to overcurrent.

2.  Calculate the amps required for each appliance using the circuit breaker rating in the load center. No appliance should have an amperage rating that exceeds the “Generator Main” rating in the transfer switch. The total amperage of all circuits can exceed the generator rating, but not all circuits will be able to be used concurrently.

3.  Assign the circuit number in the load center and in the manual transfer switch, matching the size of the circuit breaker in the load center to the circuit breaker in the transfer switch. Once you’ve determined which circuits you want to connect and the appropriate amperage, you will be ready to physically insert the manual transfer switch.

More information on transfer switches