How to connect a generator to your house safely

This page is an overview, so you can plan and talk to an electrician with confidence. It is not a wiring guide. Connecting anything to your home's wiring is licensed-electrician work.

Your safe options at a glance

Option	What it powers	Who sets it up	Wiring work
Extension cords	Only things that plug in	You	None
Interlock kit + inlet box	Any circuit in your panel, a few at a time	Licensed electrician, usually with a permit	Usually less
Manual transfer switch + inlet box	Only the circuits wired to it	Licensed electrician, usually with a permit	More

Not sure between the last two? Our interlock vs transfer switch guide compares them in detail.

Option 1: Extension cords (no wiring at all)

The simplest safe way is to skip the house wiring. NFPA says to plug appliances "directly into the generator or a heavy duty outdoor-rated extension cord." Ready.gov says the same: connect appliances with heavy-duty extension cords.

• Good for: a fridge, a freezer, lamps, phone chargers, a window AC, a CPAP.
• Not good for: anything hard-wired. That includes a furnace, a well pump, a sump pump wired into a box, ceiling lights and most water heaters.
• Check every cord. NFPA says to look for cuts and tears, and make sure the plug has all three prongs.

If you want the furnace or well pump on, you need option 2 or 3.

Options 2 and 3: An interlock or transfer switch, with an inlet box

Both let your generator feed your home's circuits safely. Both stop the generator and the utility from ever being connected at the same time.

• A transfer switch is a small separate panel. You flip chosen circuits from "Line" to "Generator."
• An interlock kit is a sliding plate on your main panel. It stops the main breaker and a generator breaker from being on together.

With either one, the generator plugs into a power inlet box. That's a weatherproof socket mounted on an outside wall. One cord runs from the generator's outlet to the inlet.

OSHA's rule: don't attach a generator to a building's electrical system "unless a qualified electrician has properly installed the generator with a transfer switch." Honda's manual likewise says not to connect to a building's electrical system unless an isolation switch "has been installed by a qualified electrician."

What the electrician does

A good electrician will usually:

1. Look at your panel and decide whether an interlock kit is available and listed for it, or a transfer switch fits better.
2. Help you pick circuits and check them against your generator's watts. Our what size generator to run a house guide helps you plan this first.
3. Install the inlet box on an outside wall, sized to match your generator's outlet.
4. Install the interlock or transfer switch, with a breaker sized to match.
5. Sort out grounding and the neutral. Generac says that when you connect to a panel or transfer switch, the generator needs a ground rod. Champion explains that some setups, like a transfer switch that doesn't switch the neutral, call for a "floating neutral" generator. Champion adds that a qualified electrician should decide this.
6. Pull the permit and have the work inspected.
7. Show you the switch-over steps, and the order to do them in.

Permits and your utility

NFPA says a transfer switch should be installed by a qualified electrician "in accordance with the National Electrical Code (NEC) and all applicable state and local electrical codes." In most places, that means a permit and an inspection.

Champion's manual says to notify your utility company before you connect your generator to your power system. It also notes that in some areas, generators must be registered with the local utility. Ask your electrician what applies where you live.

Match the inlet to your generator

The inlet box, the cord and the generator's outlet must all match.

Generator outlet	Volts	Most it can carry
L14-30 (4-prong, 30 A twist-lock)	120/240 V	7,200 W
14-50 (50 A)	120/240 V	12,000 W

The outlet sets the ceiling, not the generator. WEN rates its L14-30 adapter at 30 A and 7,200 W, and its 50 A 14-50R parallel kit at 12,000 W. So a generator rated above 7,200 running watts still can't push more than 7,200 W through an L14-30 inlet.

Worked example: The Westinghouse WGEN7500DFc is rated 7,500 running watts, and its 240 V outlet is an L14-30R. Through that one outlet: 30 A × 240 V = 7,200 W. So your house circuits get up to 7,200 W, not 7,500. For a bigger feed, you'd need a generator with a 14-50R outlet and a 50 A inlet. See 30 amp vs 50 amp generator cords.

Need 240 V? A well pump or other 240 V load needs a generator with a 240 V outlet. A 120 V-only generator can't run it.

How a switch-over usually goes

Your electrician's steps for your setup come first. The general order is:

1. Put the generator outdoors, at least 20 feet from the house, with the exhaust pointed away.
2. Connect the cord to the generator and the inlet box.
3. Start the generator with nothing connected, and let it warm up.
4. Interlock: switch the main breaker OFF, slide the plate, then turn the generator breaker ON. Transfer switch: flip circuits to "Generator."
5. Turn big loads off first, then turn circuits on one at a time.
6. When utility power returns, reverse the steps.

Never do these

• Never plug a generator into a wall outlet or dryer outlet. OSHA warns this backfeed "can energize wiring systems for great distances," putting utility workers and others at risk of electrocution.
• Never use a double-ended "suicide cord." It's a backfeed cord with live, exposed prongs.
• Never wire a generator into your panel without a transfer switch or a listed interlock.
• Never run the generator in the garage, even near the inlet box. It stays outdoors, 20+ feet away. See how far a generator should be from the house.

Run it outdoors only, 20+ feet from the house, away from windows and doors: generator carbon monoxide safety.