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How to Hook Up a Generator to Your House: 3 Safe Ways
There are three safe ways to hook up a portable generator to your house: extension cords to individual appliances, a manual transfer switch, or an interlock kit with a power inlet box. The one thing you should never do is plug the generator into a wall outlet. The CPSC warns that this practice, called backfeeding, is extremely dangerous and presents an electrocution risk to utility workers and neighbors on the same transformer.
Why you can't just plug into an outlet
A generator plugged into a wall outlet sends power backward through your panel and out to the utility lines. OSHA says to never attach a generator directly to a building's electrical system unless a qualified electrician has installed it with a transfer switch. When a generator is connected to your house wiring, Reliance Controls notes, the National Electrical Code requires a transfer switch.
The 3 safe ways, compared
| Method | What it powers | Electrician? | Typical installed cost |
|---|---|---|---|
| 1. Extension cords | Plug-in appliances only (fridge, freezer, lights, TV) | No | Cost of heavy-duty outdoor cords |
| 2. Manual transfer switch | Selected hard-wired circuits (furnace, well pump, lights) | Yes | $400 to $1,300 |
| 3. Interlock kit + inlet box | Any circuit in your panel, within the generator's watts | Yes | $400 to $850 |
Installed costs are from HomeGuide's transfer switch installation cost guide. An automatic transfer switch, used mostly with standby generators and some home batteries, runs $600 to $2,500 installed per the same guide.
Option 1: Extension cords (no wiring)
Run heavy-duty outdoor extension cords rated for the load from the generator to each appliance. It is the simplest setup, but it cannot reach hard-wired loads like a furnace blower, well pump, or ceiling lights. Keep cords out of standing water and do not run them under rugs.
Option 2: Manual transfer switch
A manual transfer switch mounts next to your main panel and is wired to the circuits you choose. You plug the generator into an outdoor power inlet box, then flip each circuit from utility to generator. Because each circuit is switched one at a time, it is easy to stay within your generator's capacity. Read our full generator transfer switch guide.
In-stock transfer switch kits that include the inlet box and cord:
- Reliance 306CRK: 6-circuit prewired switch, 10 ft L14-30 power cord, and PB30 outdoor inlet box. Up to 7,500 generator running watts. $349
- Reliance 310CRK: 10-circuit switch with a 30 amp inlet box and a 10 ft 30 amp cord. Up to 7,500 running watts. $479
- Reliance 310CDKN: 10-circuit prewired switch, 30 amp inlet box, and 20 ft 30 amp cord. $661.20
Need it outdoors? The Reliance R310A (30 A, 10 circuits, UL 1008 listed, $459) mounts outside. Browse all transfer switches.
Option 3: Interlock kit and power inlet box
An interlock kit is a plate that mounts on your panel cover so the main breaker and a generator breaker can never be on at the same time. The generator feeds a double-pole breaker in your panel through an outdoor inlet box, and you choose which circuits to run by turning breakers on and off. It is usually the lowest-cost way to reach every circuit in the house. Kits are panel-specific, so match the kit to your panel's brand and model.
- GenInterlock kits for Square D, Eaton, Siemens, GE, and more: $49.95 to $69.95
- Nature's Generator 30 A power inlet box: L14-30P inlet, up to 7,500 W. $29.99
- Nature's Generator 50 A power inlet box: for larger generators with a 50 amp outlet. $49.99
Step-by-step details are in our generator interlock kit installation guide. Still deciding? Compare them in interlock kit vs transfer switch.
Match the generator to the hookup
| Inlet / cord | Generator outlet | In-stock generator |
|---|---|---|
| 30 A, L14-30 | L14-30R | DuroStar DS8000iX: 8,000 starting / 6,500 running watts, inverter, CO alert. $999 |
| 30 A, L14-30 | L14-30R | DuroMax XP5500HX: 5,500 starting / 4,500 running watts, CO alert. $629 |
| 50 A, 14-50 | 14-50R | DuroMax XP9500iH: 9,500 starting / 7,600 running watts, inverter, CO alert. $1,999 |
| 50 A, 14-50 | 14-50R | DuroMax XP13000EH: 13,000 starting / 10,500 running watts. $1,299 |
Not sure how big a generator you need? Read What Size Generator Do You Need to Run a House? Backing up with a battery instead? See transfer switch for a solar generator.
Safety rules that apply to every method
- Use a licensed electrician for any transfer switch or interlock install. Most towns require an electrical permit, so check with your local building department.
- Keep the generator outside, at least 20 feet from windows, doors, and attached garages, per Ready.gov. Never run it indoors or in a garage, even with the doors open.
- Turn the generator off and let it cool before refueling. DuroMax's manual says to allow the engine to cool for several minutes first.
- Size the cord to the outlet. A 30 amp inlet needs a 30 amp cord; a 50 amp inlet needs a 50 amp cord.
Need help choosing? Call 1-888-855-7286. Tell us your panel brand and what you want to back up, and we will help you pick a transfer switch or interlock kit and a matching generator.
Generator hookup FAQ
Can I plug a generator into a wall outlet? No. The CPSC calls backfeeding extremely dangerous because it can electrocute utility workers and neighbors.
What is the cheapest safe way to connect a generator to my house? An interlock kit with a power inlet box. HomeGuide puts the installed cost at $400 to $850, and the kits themselves run about $50 to $70.
Do I need an electrician to hook up a generator? For a transfer switch or interlock kit, yes. Extension cords to individual appliances do not require any wiring.
What size generator do I need for a 30 amp inlet? A 30 amp L14-30 inlet carries up to 7,500 watts. Generators like the DS8000iX (6,500 running watts) fit that hookup.
Is a transfer switch required by code? When a generator connects to house wiring, the National Electrical Code requires a transfer switch, according to Reliance Controls. An interlock kit listed for your panel is the common alternative.