Quick answer: A listed panel interlock or a manual transfer switch, paired with a generator inlet box, lets you power home circuits from a portable generator without backfeeding the utility grid. An interlock lets you choose any circuits in the panel but requires managing loads manually. A transfer switch powers pre-selected circuits. Both should be installed by a licensed electrician with a permit. Never connect a generator through a dryer or wall outlet.

After a storm knocks out power across the Lowcountry, many homeowners pull out a portable generator. How it connects to the house determines whether it is a convenience or a hazard.

The dangerous way: backfeeding

Connecting a generator to a home outlet with a double-male cord, sometimes called a "suicide cord," energizes household wiring and can send power back onto utility lines. It can electrocute line workers and neighbors and can damage the generator and home when utility power returns. It is never safe.

Option 1: Panel interlock kit

An interlock is a mechanical device installed on the panel that prevents the main breaker and the generator breaker from being on at the same time.

  • Pros: Lower cost, flexibility to power any circuit in the panel
  • Cons: You must turn circuits on and off to stay within the generator's capacity
  • Requirement: The interlock must be listed for your specific panel.

Option 2: Manual transfer switch

A transfer switch is a separate subpanel with selected circuits, such as the refrigerator, some lights, internet equipment, and a well pump, that can be switched from utility to generator power.

  • Pros: Simple to operate, reduces the risk of overloading
  • Cons: Higher cost, limited to the circuits chosen at installation

Both need an inlet box

A generator inlet box mounted outside lets you plug in the generator with a properly rated cord. Place the generator more than 20 feet from the house, doors, and windows, as CDC guidance advises, and never run it in a garage.

Thinking about automatic backup instead?

If you want power that starts on its own, read our standby generator guide.

Frequently asked questions

Is a generator interlock legal?

A listed interlock kit installed on a compatible panel by a licensed electrician, with a permit where required, is a recognized safe method.

Which is better, an interlock or a transfer switch?

An interlock offers flexibility at lower cost but requires managing loads. A transfer switch is simpler to use but limited to pre-selected circuits.

Can I plug my generator into the dryer outlet?

No. That backfeeds the home's wiring and can energize utility lines, creating a deadly hazard.

How far should a portable generator be from my house?

CDC guidance is more than 20 feet from your home, doors, and windows, and never inside a garage, even with the door open.

Copperhead Electrical serves homeowners across Charleston, Mount Pleasant, West Ashley, James Island, Johns Island, Daniel Island, North Charleston, and Summerville. Call 854-444-6516 or request service online.