Question 1

Is a generator interlock legal?

Accepted Answer

Yes, when the interlock is UL-listed for your specific panel brand and installed with a permit. Homemade sliding plates are illegal and dangerous.

Question 2

Interlock vs transfer switch — which is right for me?

Accepted Answer

Interlock is cheaper ($800–$1,500 installed) and lets you power any circuit in the panel. Transfer switch is more convenient (dedicated circuits pre-selected) and required for automatic operation.

Question 3

What size generator works with an interlock?

Accepted Answer

Any portable generator with a 30A (L14-30) or 50A (14-50) outlet. Common sizes are 5,000W–12,000W.

Question 4

Can any panel accept an interlock kit?

Accepted Answer

No. The interlock must be manufacturer-listed for your specific panel model. Square D QO, Homeline, Eaton BR, and Siemens have listed kits; some older or specialty panels don't.

Question 5

How do I use the interlock during an outage?

Accepted Answer

Turn off the main breaker, start the generator outside, plug it into the inlet, then turn on the generator breaker. Manage circuits by only turning on breakers within generator capacity.

Question 6

Where is the generator inlet installed?

Accepted Answer

Exterior wall closest to where you'll park the generator, at least 15 feet from the meter and any window per code and manufacturer instructions.

Question 7

How much does interlock installation cost?

Accepted Answer

Most installs run $800–$1,500 including inlet, breaker, interlock plate, wiring, and permit.

Question 8

Can I run my whole house on an interlock?

Accepted Answer

You can turn on any breaker, but generator capacity limits what runs at once. A 7,500W generator handles fridge + furnace + sump + lights — not central AC.

Question 9

Do I need a permit?

Accepted Answer

Yes — every DMV jurisdiction requires a permit and inspection for interlock installation.

Question 10

How long does installation take?

Accepted Answer

Typically 3–4 hours including inlet mounting, wiring, and testing.

Generator Interlock Kit Installation

What's included

Our process