Installation
Generator interlock kit installation
A generator interlock kit is a mechanical slide on the main panel that prevents the main breaker and the generator breaker from being on at the same time. With an exterior power inlet, it lets a portable generator power chosen circuits without backfeeding the utility.
- Call now to check electrician availability in your area
- Licensed, independent electricians
- 48 states + DC
About generator interlock kit installation
Plugging a generator into a wall outlet, or a "suicide cord", can send power back onto utility lines and injure line workers. An interlock and inlet box is the lower-cost, code-compliant alternative to a full transfer switch.
With an interlock, you choose which circuits to run during an outage, such as the furnace blower, refrigerator, sump pump and some lights, within the generator's capacity.
- Generator Interlock Kit Installation at a glance
- Installation
- Who does the work
- An independent licensed electrician
- Urgent calls
- Usually scheduled
- Typical first step
- Match the panel
Signs you need this
- You own or plan to buy a portable generator
- Outages in your area last hours or days
- You need to keep a sump pump, furnace or well pump running
- You want backup power without a standby generator
What the electrician does
- 1
Match the panel
The electrician confirms an interlock kit is listed for your panel model.
- 2
Install the inlet
An exterior power inlet box is mounted near where the generator will run, away from windows.
- 3
Install interlock and breaker
The generator breaker and interlock are installed in the main panel.
- 4
Test and inspect
Changeover is tested and the work is inspected.
What affects the cost
Electricians set their own prices. These are the factors that move a quote up or down, so you can compare like for like.
- Interlock kit availability for your panel
- Inlet amperage (30 or 50 amp)
- Distance from panel to inlet
- Generator cord length and type
- Permit fees
What you can do safely, and when to stop
Safe to do
- ✓ Know your generator's running and surge wattage
- ✓ List the circuits you want to power
Stop and call
- ✕ Never backfeed through an outlet
- ✕ Never run a generator in a garage
Generator Interlock Kit Installation FAQ
Is an interlock kit legal?
Yes, when it is listed for your panel and installed with a permit; it is a recognized way to prevent backfeeding.
Interlock kit or transfer switch?
An interlock uses your existing panel and lets you pick circuits; a transfer switch has dedicated circuits or switches automatically with a standby generator.
What can a portable generator run?
Typically a furnace blower, refrigerator, sump pump, lights and a few outlets, depending on its wattage.
Where should the inlet go?
Outside, near a safe spot to run the generator, well away from doors, windows and vents.
How long does installation take?
Often a few hours when the panel and inlet location are close.
Where electricians offer this
Local guides to generator interlock kit installation in cities where local housing makes it a common job:
By state:
Available through our network in 48 states and DC. Metro guides:
Related services
Generator Installation
A generator must connect through a transfer switch or an approved interlock so it can never feed power back into utility lines.
Learn more →
Whole-Home Surge Protection
A whole-home surge protective device (SPD) mounts at the panel and limits voltage spikes before they reach your circuits.
Learn more →
Dedicated Circuits
A dedicated circuit serves one appliance or one heavy-use area so it does not share capacity with anything else.
Learn more →Need help with generator interlock kit installation?
Call now and we connect you with a licensed electrician who serves your ZIP code.