What is the difference between a generator interlock and a transfer switch?

Both safely connect a generator to home wiring by making sure the home can't be tied to the utility and the generator at once. An interlock kit is a mechanical device on the main panel that prevents the main breaker and the generator breaker from being on at the same time, according to Purdue Extension. A transfer switch is a separate switch that moves selected circuits, or the whole house, from utility power to generator power; automatic versions start the generator and switch over on their own. OSHA says a generator should connect to a building's wiring only through a transfer switch installed by a qualified electrician. Check what your local inspector and utility accept.

Check your local rule. This varies by state, county or city. Your permitting office has the final word; the official lookup pages below show you who that is.

Sources

• Generator Interlocking Circuit Breaker KitPurdue University Extension (4-H Electric)
• Using Portable Generators SafelyU.S. Occupational Safety and Health Administration