Both make it safe to power your home from a generator. An
interlock is a mechanical plate on your panel that lets you run selected circuits from a portable generator. It’s the most affordable option. A
transfer switch is a separate switch for chosen circuits or the whole house, and an
automatic transfer switch is what standby generators use. Want help? See our
generator installation service.
How an Interlock Works
A sliding plate on your panel physically prevents the main breaker and the generator breaker from being on at the same time. You plug the generator into an outdoor inlet, turn off the main, and switch on the circuits you need.
How a Transfer Switch Works
A separate panel or switch moves selected circuits from utility power to generator power. Manual switches are flipped by hand. Automatic switches detect an outage and start a standby generator on their own.
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Which to Choose
| Your situation | Best fit |
|---|
| Portable generator, essentials only, lowest cost | Interlock with an inlet |
| Portable generator, a set group of circuits | Manual transfer switch |
| Standby generator, automatic backup | Automatic transfer switch |
Never Backfeed
Plugging a generator into a dryer outlet or wall outlet sends power back onto the utility lines, which can electrocute line workers. An interlock or transfer switch is the only safe way. Both need a permit.
