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Question DetailsAsked on 8/30/2014

Constant hum in wall next to where electrical current enters house but sound stops if turn off 1 circuit breaker

Electrician blamed power company. Power company came and saw no problem on their end but they could hear sound/hum too in pipes leading to outside power box. I asked about transformers sending in more electricity but don't have an answer on that. (I opted out of smart meter)
The other night lights flickered when AC went on. There are no new sources of electric uses in my 70 year old town house.

So do I need a new circuit box? OR could it still be the power company?

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3 Answers


Check to see what doesn't work when that 1 circuit breaker is turned off.

My guess is it could be the transformer for the dorbell that is humming. They often mount that transformer close to the main breaker panel and is is always energized,so constant hum is possible.


Answered 6 years ago by BayAreaAC


Could also be a bad or loose circuit breaker, a loose wire or any number of things. The one thing that is certain I would think is it is definitely on that circuit and a good electrician shouls be able to find it and not just pass the buck off to the power company.


Answered 6 years ago by ContractorDon


BayAreaCool and Contractor Don's suggestions are on the mark as usual - find out what is on that circuit, then start tracing along it to find the offending item. Because turning off one breaker stops it (unless you are talking the main house breaker), almost certainly related to something powered by that breaker, not a main feed issue.

The power company transformer cannot send in more power than is demanded - sort of like your city piping can supply a massive flow of water but does not send more than can be produced by the open faucets.

It is possible for a loose mounting in a meter base or meter or conduit to hum like that, as can a loose wiring connection vibrating or a main breaker going bad, but your electrician should have checked for those. A short between the wires in the mainfeed can cause a buzz or humm also, but normally would bereadily detectable by heating of the wire or conduit, which presumably the electrician checked out - but maybe not. But not something you want to check by hand while the power is on.

If it were me I would use my stethoscope to trace the hum location - you could do that, checking from the outside meter box to the breaker panel, then along the circuit that stops it when shut off to find loudest point - but do not touch any of the pipes or boxes directly just in case there is a short somewhere. Don't forget to track downward or upward as applicable next to the incoming power lines - in case it is humming in the incoming conduit. At times, a small short in power lines can start as a hum or buzz from the power being drawn, before it develops into a complete short and arcs out.

Like one of the other comments - I would first guess a transformer somewhere - doorbell, low voltage lighting for yard or kitchen, charger for an electronic device, constant-on device like TV, even a jammed garage door opener or stalled out pool/fish pond pump. If a loudly humming transformer, replace it - sometimes tht is harmless,but sometimesindication of an internal problem which can cause overheating and then failure.

Also immediately check your A/C and furnace - could be you have a starter problem like a stuck starter solenoid or contact or a stalled fan or compressor that is humming loudly - if so, shut the power off till fixed as can burn out motor.

If you turned off all sources of noise, including furnace and A/C, at night when it is quieter (less street noise), I would think you could just walk around the outside and inside of the house and find the source just by ear if it is loud enough to hear from inside the house.

Definitely NOT a new breaker box issue - at worst a wiring problem or maybe one breaker going bad, but this is a diagnosis and minor fix issue, not a major replacement issue.

Lights flickering when AC came on is not unusual, though if not normal for your unit could be indicative of a problem.

I wouldnot take this likely - not because it is "likely" serious, but because it has the potential to be in some cases, so should be considered a fire and electrical short risk until proven otherwise.

Feel free to respond back if you want after you have investigated a bit more, using the Answer This Question button right below your question.

Answered 6 years ago by LCD

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