Generator Transfer Switch Installation with your electrical project

Decide what you actually need running

Most portable-generator installations back up selected circuits rather than the whole house: heating controls, the refrigerator, a well pump, some lighting, one or two receptacle circuits. Air conditioning, electric ranges, water heaters and dryers are usually out of reach on a portable generator.

Watch for: A circuit list assembled without checking the starting current of motor loads. A well pump can draw several times its running current at start-up, and a generator that copes on paper stalls in practice.

Manual, automatic, or an interlock kit

A manual transfer switch means you start the generator and throw the switch yourself; an automatic one senses the outage and does it for you. A panel interlock kit is a third option — a listed mechanical device making it physically impossible to close the generator breaker and the main breaker at once. It is accepted in many jurisdictions, costs considerably less, and gives access to any circuit in the panel.

Watch for: Interlock kits that are not listed for your specific panel. A generic plate is not the same product, and an inspector will know the difference.

Inlet, cabling and where the generator stands

A power inlet box is fitted outside and a cable of the right rating connects the generator to it. Position matters for a reason unrelated to electricity: generators produce carbon monoxide, and must be run well away from the house and never in a garage, a porch or anywhere partly enclosed.

Watch for: An inlet fitted where the only convenient generator position is near a door, window or air intake. The carbon monoxide risk is what actually kills people.

Permit and inspection

Permitted work in most jurisdictions. The inspection covers the switching arrangement, the inlet, and the grounding and bonding — which differ depending on the generator's own configuration.