I've had an issue recently where turning on the light in one room occasionally turns off the power in that breaker. The breaker doesn't actually appear to be tripped, but resetting the breaker will restore power.

However, when I do so, there is an audible buzzing and crackling noise for 1-2 seconds when the breaker is first powered back on. Why is that and, more importantly, how do I fix that?

My first thoughts, from a non-electrician stand-point, is that the breaker is damaged and needs to be replaced. This could also explain why it stops working occasionally. Maybe it's no longer using the voltage that it's rated for.

Any ideas?

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    Does this breaker have a "TEST" button? Can you tell us the brand name and subtype of the panel (Cutler Hammer BR, Square D QO, Westinghouse Zinsco, that sort of thing)? Commented Jul 9, 2019 at 23:20
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    Can you post photos of the panel for that matter? Does the breaker wobble slightly if you put your finger on its front and try to wiggle it up-and-down? Commented Jul 9, 2019 at 23:39
  • An anecdote: I used to have a wirelessly controlled light switch to turn on and off a security light (a fairly large reactive load.) When the light was on, the a buzzing went throughout the entire electrical system. I've since removed that switch and the problem went away.
    – Duston
    Commented Jul 10, 2019 at 15:33
  • Hello, and welcome to Home Improvement. We'll need more info before we can help you. And, you should probably take our tour so you'll know how best to participate here. Commented Jul 10, 2019 at 16:55
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    It's a vintage panel made by CEB Limited. It's a BC24100 100AMP panel. I believe that specific panel has bolt-on QBH breakers. The breaker in question is a 40AMP double-pole (I believe that's the term for two breakers with an adjoined switch) breaker. It does not appear to be tripped, but resetting it works. It's only an issue in the summer, although this house has no air conditioning, so power consumption is roughly the same year-round. Commented Jul 10, 2019 at 17:58

1 Answer 1


CEB Ltd. is a now obsolete panel mfr., but they used Cutler Hammer circuit breakers. You can still buy those breakers from Eaton (the new name for Cutler Hammer) and they still use the same part numbers.

Those are "bolt-on" circuit breakers, meaning the way they connect to the panel bus bars is a bolt (screw) instead of a stab-in arrangement. Bolt-on breakers are mostly used in industry, not residential because industrial and commercial users are usually moving and modifying circuits more often, so plug-in breakers get loose and sloppy over time. The down side to bolt-on breakers though is that the connections must be periodically tightened, something that an industrial user would have as part of a routine maintenance program. Most homeowners however are unaware of this need, hence the preference for stab-in breakers.

The point is, the buzzing sound is often a sign of that bolted connection getting loose, and it is VERY dangerous as it could eventually start a fire! If you are uncomfortable with messing with the guts of your panel, hire an electrician immediately. They (or you) must remove that breaker and clean off all mating surfaces on the breaker tang and the bus bars before re-assembling it. DO NOT just tighten up the screw as there is likely debris in there now from arcing that has been taking place.

  • My understanding is from mechanical lugs, which the vendors say do not need periodic retightening (if something came loose, it was torqued wrong to begin with) -- do busbar bolt-downs behave differently? Or was this a case of something that never was right to begin with? (Seconded on taking the culprit joint apart and cleaning it up, though -- that's the recommended cure for a mistorqued joint, provided you use a torque tool to tighten it down properly when you're putting it back together, of course!) Commented Jul 11, 2019 at 1:32
  • Mechanical lugs are different, they (most) are designed using hardened aluminum with specially designed steel set screws designed to jam against the threads in the lug body and not loosen over time (although "never" is an ambitious idea).
    – JRaef
    Commented Jul 11, 2019 at 2:00
  • Bolted bus connections on small breakers like this are not designed this way because the threads are going into the soft copper or aluminum bus. Then you have a steel machine screw and copper or aluminum bus, which expand and contract at different rates, so over time the connections can loosen. On larger breakers, special concave spring washers (called "Belleville washers) are used to help keep them tight for longer, but all bolted connections should be checked periodically.
    – JRaef
    Commented Jul 11, 2019 at 2:00
  • Thanks for the explanation, it makes more sense now why things could get sloppy over time in a bolted bus connection (also, Belleville washers are awesome <3) Commented Jul 11, 2019 at 2:24

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