Transfer Switch vs. Interlock Kit - Which Hookup Is Right?
Last verified: September 2026
Two safe ways to wire a generator into your panel, compared in plain English — how each works, what they cost, and how to choose the one that fits your home. Rather talk it through? My number is (330) 200-8042.
Transfer Switch vs. Interlock, at a Glance
Both a transfer switch and an interlock kit safely connect a generator to your panel, and both are a licensed electrician's job. A transfer switch is a separate box of labeled switches that physically isolates the generator from the utility; an interlock kit is a UL-listed plate on your existing panel that does the same safety job for less. This guide compares them — cost, circuits, the 240-volt well-pump question, and how to choose. There's a printable page-by-page version up top.
Common Questions
1 What's the difference between a transfer switch and an interlock kit?
A transfer switch is a separate box of labeled switches that hands chosen circuits between utility and generator power. An interlock kit is a UL-listed plate on your existing panel that stops the main and generator breakers from being on together. Both isolate the generator safely; the difference is cost, circuits, and convenience.
2 Is one safer than the other?
No. Both keep generator and utility power from ever meeting, which is the core safety job, and both are installed by a licensed electrician. The choice comes down to fit — budget, how many circuits you want, and how hands-on you like to be.
3 Which one lets me power more circuits?
An interlock kit usually does, because it works through every breaker in your existing panel. A transfer switch covers only the circuits it was wired for, chosen in advance — tidy, but adding more later usually means another visit.
4 Do I need one if I'm on a well?
Almost certainly. A well pump is a hardwired 240-volt load that cords can't reach, so you need a panel hookup — a transfer switch or interlock kit — paired with a 240-volt-capable generator sized for the pump's starting surge.
5 Do both need a permit and an inlet box?
Yes. Both are panel work that typically needs a permit and inspection, and both connect through a weatherproof inlet box mounted on your outside wall — see our inlet-box guide for that piece.
6 How much does each cost?
An interlock kit is usually the more affordable hardware; a transfer switch typically costs more. Both add a licensed electrician's visit and usually a permit. For real numbers, get a quote from a licensed electrician rather than trusting a figure online.
Would You Rather I Just Help?
Deciding between a transfer switch and an interlock kit, planning your circuits, and lining up the electrician is exactly what I help with. I'll look at your home and your must-run list, with nothing to sell you. $99 flat for a visit, 30-day come-back-free.
Would you rather I just do this for you?
No shame in it — plenty of folks would rather hand it off, and that's what I'm here for. I'll come to your home, set it up right, and make sure it's working before I leave. Flat $99 per visit — no jargon, no upsell, and every visit is 30-day come-back-free.
Not a hardware job? I can often fix it remotely for $49 — a secure screen-share, up to 2 hours, that you watch the whole time and can end whenever (included free for $39/mo Support Plan members, and it counts toward the $99 if it turns out I need to come out).