My main breaker box is not working. My secondary one is. So most of my household without power. Then at 937 at night the power in my house comes on very low and stays on for a couple of he's before it goes off again. What would cause this?

  • Where are you located? Is the box that is 'not working' blown out, or not attached, or bridged? 937 does not sound like nighttime - 9:37 am/pm, or some other time? – bukwyrm May 14 '18 at 20:30
  • what is he's ... here it means he is – jsotola May 14 '18 at 20:50
  • how does the secondary breaker panel get power? ... is it not connected to the primary breaker panel? – jsotola May 14 '18 at 20:56
  • We need more details and pics, i.e. Be nice to know if the panel is a Rule of Six. @bukwyrm he means 21:37. Aside from more details we could also use less obviously-irrelevant detail. – Harper May 14 '18 at 21:31
  • Can we have photos of both breaker boxes involved? Also, is your electric meter measuring any consumption while the power is off? And is there a breaker in the main breaker box that turns off power to the secondary breaker box? – ThreePhaseEel May 14 '18 at 22:09

I suspect you have a meter. If not, get one. Harbor Freight has them for less than $15. You say your main circuit is not working, but your sub-panel is, is that correct? I suspect that one leg of your main panel is not working and the other one is. To test this, remove your cover from your panel box. Remove your wedding ring....trust me, it is a good idea. Set your meter to 200 volts AC. Touch one probe to the point where the black wire comes in and fastens to the box' Touch your other probe to the box itself. You should have a reading of 115v to 122v. If so, this side is good. Repeat for the other side with the red wire. This will be good or bad. I suspect one side is bad. I say this because your sub-panel cannot be working if your main panel is totally dead.

The other issue has to do with your ground or neutral. With wedding ring off, go down your neutral and ground bars and make sure they are all tight.

Why wedding ring off? Because it can cause arcing, and you would not be happy with that!

  • 1
    I got the wedding ring speech > 20 years ago from a computer manufacturer about working on power supplies (he told a story about "three fingers Brown" who wasn't so careful...). Working inside a breaker box, especially if you have never done so before, requires a bit more caution than just taking off your rings & watch. – manassehkatz May 15 '18 at 4:05
  • It depends on how the sub is fed, if fed prior to the main it could be a bad breaker (or the main disconnect in the panel.) Also if a 240v load is on you could see voltage on each leg measuring from 1 hot to the other coming into the panel this could be any thing from 200 to 250 depending on the service type. – Ed Beal Jul 4 '18 at 16:10

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