How to Connect a Generator to Your House Safely
By the Generator Hubs team · Updated · 6 min read
The safe ways to power home circuits with a portable generator: transfer switch, interlock kit or extension cords. Never backfeed through an outlet.
A portable generator can power more than a few extension cords. With the right equipment, it can feed your furnace, well pump and lighting circuits directly. Doing it safely matters for you, your home and utility line workers.
Never backfeed through an outlet
Plugging a generator into a wall outlet with a double-ended cord sends power back into the utility lines. It can electrocute line workers, damage your wiring and start a fire. It is illegal in most places.
Option 1: a manual transfer switch
A transfer switch is installed next to your main panel and wired to the circuits you choose. You plug the generator into a power inlet box outside, then move each circuit from "line" to "generator". The switch makes it impossible to connect the generator and the utility at the same time.
Option 2: an interlock kit
An interlock is a plate on your main panel that prevents the main breaker and the generator breaker from being on together. It costs less than a transfer switch and lets you choose circuits at the panel. Check that a kit exists for your exact panel model and that it is accepted by your local code.
Option 3: heavy-duty extension cords
For a few appliances, outdoor-rated extension cords of the correct gauge are the simplest option. Run them from the generator to each appliance. Do not run cords under rugs or through closed doors where they can be pinched.
What you need for a transfer switch or interlock
- A generator with a 30 A (L14-30) or 50 A (14-50) outlet.
- A matching generator cord and power inlet box.
- A licensed electrician and, in most areas, a permit.
Placement
Run the generator outdoors only, at least 20 feet from the house, with the exhaust pointing away from doors, windows and vents. Read our generator safety guide before the first use.
Frequently asked questions
Do I need an electrician to install a transfer switch?
Yes. Transfer switches and interlock kits connect to your main electrical panel and should be installed by a licensed electrician, usually with a permit.
Which generator outlet do I need for a transfer switch?
Most home transfer switches use a 30 A L14-30 or 50 A 14-50 connection. The generator must have the matching outlet.
