How to Connect a Portable Generator to Your House — Safely
Extension cords, generator inlets, interlock kits, and transfer switches compared — with costs — and why backfeeding through a dryer outlet can kill a lineworker.
Updated July 15, 2026
There are exactly three legitimate ways to get generator power into your house, and one infamous way that shows up in news stories. The right choice depends on how many circuits you need and whether you're willing to have an electrician out for half a day. Here's how each actually works, what it costs, and where people get hurt.
Option 1: Extension cords (about $50–$150, no electrician)
The generator stays outside and heavy-gauge cords come in through a window or door to individual appliances. It's the zero-install option and it's completely legitimate for a fridge, a freezer, some lamps, and chargers. The limits: anything hardwired (furnace blower, well pump, ceiling lights) can't be reached, cords across doorways are a trip-and-pinch hazard, and undersized cords overheat. Use 12-gauge or heavier for anything with a motor, and keep runs as short as practical.
Option 2: Generator inlet + interlock kit (roughly $400–$1,000 installed)
An electrician mounts a male inlet box outside, wires it to a breaker at the top of your panel, and fits a sliding metal interlock plate that makes it physically impossible to have that generator breaker on at the same time as the utility main. You backfeed the whole panel legally and safely, then choose which circuits to run by flipping breakers. This is the best value in home backup: one cord, every hardwired load reachable, and load management is just breaker discipline. The catch — it's manual, and the interlock must match your exact panel model to pass inspection.
Option 3: Manual transfer switch (roughly $500–$1,500 installed)
A small sub-panel beside your main panel with 6–10 chosen circuits moved into it. Flip the switch and those circuits — and only those — run from the generator. It's tidier than an interlock for non-technical households because the choosing was done on install day, and some models have built-in wattage meters that make load balancing obvious. Less flexible, though: if the circuit isn't in the switch, it doesn't exist during an outage.
Which one should you pick?
| Method | Typical all-in cost | Reaches hardwired loads? | Best for |
|---|---|---|---|
| Extension cords | $50–$150 | No | Renters, rare short outages, plug-in loads only |
| Inlet + interlock | $400–$1,000 | Yes — whole panel | Most homeowners; maximum flexibility per dollar |
| Manual transfer switch | $500–$1,500 | Yes — chosen circuits | Set-and-forget simplicity, non-technical operators |
| Automatic standby system | $9,000–$14,000 | Yes — everything | Frequent/long outages, medical needs, unattended homes |
If you're buying a generator in the 5,000-watt-and-up class, budget for the inlet and interlock at the same time — it's the difference between a machine that powers some cords and one that quietly runs the house. Match the inlet to the generator's biggest outlet: L14-30 (30A/240V) for most units, 14-50 (50A/240V) for the big 9,500-watt class.
Frequently asked questions
Can I just plug my generator into a dryer outlet?
No. That requires a male-to-male 'suicide cord' that backfeeds your panel and the utility lines. It can electrocute utility workers, it bypasses every safety device in the panel, and it's illegal everywhere in the US. An interlock kit does the same job — whole-panel power — for a few hundred dollars, legally.
What's the difference between an interlock and a transfer switch?
An interlock is a metal plate on your existing panel that forces you to shut off the utility main before energizing the generator breaker — every circuit in the panel becomes available, and you manage load by flipping breakers. A transfer switch is a separate small panel with pre-chosen circuits. Interlocks are cheaper and more flexible; transfer switches are simpler to operate.
What size cord do I need for a generator?
For individual appliances, 12-gauge minimum for motor loads, shorter is better, and never daisy-chain cords. For a panel inlet, use the cord rated for the connection — a 10-gauge L14-30 cord for 30-amp inlets or a 6/8-gauge 14-50 cord for 50-amp inlets — in the shortest length that reaches the generator's safe operating spot.
Do I need an electrician to hook a generator to my house?
For extension cords, no. For anything that touches the panel — inlet, interlock, or transfer switch — yes, both for code compliance and because panel mistakes are the fire-and-electrocution kind. Typical installed cost for an inlet-plus-interlock is $400–$1,000, and it usually takes an electrician two to four hours.