0

I have two 50 amp fuses that bring power from the main shutoff to my garage. When I flip the breaker in the garage all my readings seem to be normal. As I begin to turn just the lights on after I get just 3 or 4 (60 watt simple everyday led light bulbs) turned on the lights begin to dim. (The breaker box has 8 25 amp breakers in it and uses all 8 breakers for the outlets and the lights). If I have only one light on and I attempt to plug in anything into an outlet the single light I have on will lose over half of its brightness.

No matter which light I have on the above problem seems to occur. Why would it do that?

4
  • Is this an attached or a detached garage? What make and model is the breaker panel? What gauge are the wires in the walls? Mar 3 '20 at 12:41
  • 2
    Sounds sort of like a "lost neutral" problem (put that in the search box to see what I'm talking about). Picture of panel and of the 50 A fuses/shutoff would be helpful. If you have a multimeter, check voltage at outlets before & after dimming and report the results. Mar 3 '20 at 15:02
  • We’re backstabs used? Bad connections can cause a voltage drop, LED lighting that is dim-able are very sensitive to voltage variations.
    – Ed Beal
    Mar 3 '20 at 15:20
  • Yes, can you give us voltage readings as this is happening? Mar 4 '20 at 1:07
3

You've lost a wire in your feeder - probably a neutral

And this should be treated like an emergency. If it was your whole house, we'd be telling you to call the power company ASAP.

If it's a lost neutral, the problem is that while half your circuits' voltages are going down, the other half are going up - and lighting a 120V appliance up at 190V is a good way to start a fire. Also, if your main-subpanel connection is the obsolete 3-wire type, a lost neutral is energizing all your grounds and putting lethal voltage on precisely the things that are presumed to be safe.

Fortunately there are only a few places where this problem could happen; the neutral bar in either panel, or the places the hot wires terminate in either panel. There's also a possibility of wire/cable damage, but that generally happens right after construction of some kind.

If you have a 3-wire connection (hot-hot-neutral-NO GROUND) this is a very dangerous situation, because as goes the neutral, so goes the ground.

5
  • Hope so - the OP didn't indicate the age of the feeder. If it's ancient, it might not be even in a conduit & there could be decay & breakage almost anywhere. Mar 3 '20 at 19:59
  • Not gonna copy-paste the rest of the answer?
    – user253751
    Mar 4 '20 at 13:11
  • @user253751 I don't know what that means. If you think it's a dup, then VTC the question as dup, but the "lost a neutral on a subpanel" seems new. Mar 4 '20 at 14:04
  • 2
    @Harper-ReinstateMonica You are the official Lost Neutral Person of DIY Stack Exchange. I expect a lot more text in your Lost Neutral Answers.
    – user253751
    Mar 4 '20 at 14:51
  • @user253751 good point, I'm not giving lost neutral the attention it deserves. Edited. Mar 4 '20 at 15:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.