Interlock Kit for Well-Pump Backup
Last verified: September 2026
For homes on a private well, no power means no water. Here's how an interlock lets your generator power the well pump — and keeps your taps running through an outage. On a well and want reliable water? (330) 200-8042.
Well-Pump Backup with an Interlock, at a Glance
On a private well, an outage means no water at all — the electric pump stops with the grid. A well pump is hardwired and usually 240-volt, so a cord can't power it; an interlock reaches its breaker in your panel, and your generator must be sized for the pump's large starting surge. Bring the pump up on its own, then cycle it — your pressure tank buffers water so it runs now and then rather than constantly. Store drinking water too. There's a printable 29-page version up top.
Common Questions
1 Can I run an extension cord to my well pump?
No. A well pump is hardwired and usually 240-volt, which cords can't provide. It must be powered through an interlock or transfer switch, wired by a licensed electrician with a permit.
2 What size generator do I need for a well pump?
It depends on your pump. Read its nameplate or ask your well company for its horsepower, then match a 240-volt generator with enough surge capacity and headroom. See our sizing guide.
3 Why bring the pump up on its own?
The pump has a large starting surge. Starting it by itself gives that surge a clear runway; starting it alongside another motor can overload the generator. Let it settle, then add other loads.
4 Will the pump run all the time during an outage?
No — your pressure tank stores water, so the pump cycles on to refill it now and then. That lets you share generator power with the furnace, fridge, and other circuits.
5 Can undersized power hurt my pump?
Yes. Too little power can make the pump hum, strain, and overheat, and over time damage the motor. Since pumps are costly and hard to replace, size the generator generously.
6 Do I still need stored water with a generator?
Yes — keep several days of drinking water as a backstop, in case of fuel or generator trouble. The generator is one layer of your water plan, not the whole thing.
Would You Rather I Just Help?
Reliable water is one of my favorite things to help rural families plan. I'll help you find your pump's needs, plan a generator sized to protect it, work out how you'll cycle it, and coordinate a licensed electrician for the interlock and a well pro for the pump. I don't do the wiring myself. $99 flat for a visit.
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).