"Single breaker" doesn't always mean 120V


LifeTime Supporter
Jun 23, 2011
I've seen lots of threads where people have said that a single-wide breaker means your pump is 120V and a double-wide breaker means your pump is 240v. That's not always true... Who here hasn't bought a house and run into a few homeowner special modifications?

I replaced the booster pump on my Polaris earlier this spring. The main pump has a double-wide breaker in the middle of the 6-slot subpanel. A single-wide breaker in slot 2 is labeled "Polaris.". So I figure the booster pump is wired for 120V, and I start the job of replacing the old pump. Fortunately I'd taken the step of wiring the new pump for 120V before working on the old pump, and knew something was up as soon as I took off the cover plate and saw the old pump wired for 240V. I start poking around with my multimeter (smart) but manage to short out the probe and get an explosion of sparks in my lap (clumsy). Startled but unhurt I go back to the panel and find breaker 6, labeled "filter," has tripped. At least I now know how the pump is wired. Keep in mind that I've only had this house and pool for 2.5 years, so I am still finding surprises. The attic exhaust fan was another fun one, hah.

So the moral of the story is take nothing for granted, and be safe. Verify that power is really off when you're doing work. Some electrical work can be quite easy, but don't do it without the proper tools and precautions. A cheap $20 Sears multimeter can be indispensable and should be in every homeowner's toolbox.

Melt In The Sun

TFP Expert
LifeTime Supporter
Oct 29, 2009
Tucson, AZ
Soupy said:
A cheap $20 Sears multimeter can be indispensable and should be in every homeowner's toolbox.
Absolutely! And....use it! We have a breaker that was labeled "disposal", which my wife found out has nothing to do with the disposal :hammer:


Well-known member
Jun 14, 2007
New Jersey
Pulling 220V off separate single breakers is a favorite trick in Brazil, a country I lived in for 13 years and that may have the worst electricians on the planet. "Take nothing for granted" was the rule of life. Neutrals and hots from different places, 3-way switches wired in bizarre ways, and wire colors were simply decoration. (By the way, grounding is unknown in residential construction outside of kitchens.)


TFP Expert
May 1, 2007
Orlando, FL
I ran across a house once with a three-way light setup in a hallway that was fed from two breakers.
I started flipping breakers off until my partner yelled "that's it!", then I verified I had the right one by flipping it back on ("It's back on!") then off again ("OK, it's off again.") .
I switched the other breakers back on, then went into the hall to find the light back on. (WTF??!!!) Yep. TWO breakers had to be off to shut that one down.
Finally found a couple of circuits tied together in the attic.

Fun job.