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Hi,


I'm hoping an electrical engineer or experienced electrician can help here with a cause and plan of action.



I live in an apt on the ground floor of a 3 story building with 60 units. I'm being driven out of my mind by a loud noise that starts up at night when temperatures drop and/or load increases in our building. I've had to find another place to sleep.



The noise has been identified as coming from the electrical distribution box which is attached to a cement wall that runs up all three floors in my bedroom as a firewall. See pic below.



The building transformer is outside of our building and it checks out ok.

All equipment in the room below is the property and responsibility of the building owner.


Underground wires come into our building and into the box which is about 8 feet tall by about 10 feet wide. There are a couple of large power switches to switch off certain service areas. Cables split off to another electrical panels, and to two meter closets for meters for the individual units.


The noise is so bothersome but I haven't been able to get the building manager to investigate properly and fix. I can't sleep in my ground floor apt because of the noise/vibration being so loud and bothersome. An acoustic engineer confirmed the hum when it was not even bothersome.... Its in the 60-120-240 hz range. It's one time I hate having really good hearing range.

It's the left box... the whole thing is vibrating and making noise....
Really loud at times.... so loud I can hear it in my whole apartment above.


Also, there has been some flooding in the room.... but dry when this picture was taken....


Any ideas what would be causing the noise? I'm hoping I can present my findings here to the strata.
 

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Most likely lighting contactors as they come on around sundown.
Indeed.
It does seem like there is one or more (somewhat faulty) relay coils being energized at a certain time or as the result of a particular "event".
If you have access to the "room" concerned you should be able to localize the source of the sound/vibration to a particular area of "panel" behind which the faulty device is installed.
 

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Disrespectful to dirt
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It's the left box... the whole thing is vibrating and making noise....
You are not going to like the answer. That's normal. It's what switchboards do. The only thing fixable might be loose equipment or covers which may rattle or resonate, but those would create more of a buzzing or rattling sound. The hum and growl are just the equipment doing its job.
 

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Here's an old engine noise trick.
Take a large screwdriver, hold the point on the metal enclosure. Hold the Plastic handle against your ear. Move to different spots until you find the loudest point. Check the silver colored boxes between the switch gear also.
You should be able to isolate the noise. to a specific point.
 

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I agree with chandler48 - don't do anything to attempt to fix the problem. You will end up with the liability end of it which is something you do not want.


Also, I am wondering why you even have access to that equipment. You should not even be going near it.


If the noise is that bad and not allowing you to sleep the only thing you can do is report it to your landlord. You must have signed a lease. In the lease there must be a section which states that you have the right to peace and quiet (paraphrased). Read through your lease. Let the lease be your friend. Don't even call in an electrician. You can still be held liable. I would not even call an electrician if the landlord gives you permission because if an electrician that you call screws something up then you may still end up with the liability.
 

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Has it been humming all the time or just recently?

Could be a loose connection inside that is arcing which also means it is overheating and could result in ever expanding damage if not corrected.

At least the landlord/owner needs to have it investigated quickly to avoid the possible need to replace entire boxes full of equipment.

Repeat: Do not open up equipment or engage any other person to open up equipment yourself.

Almost nobody has hearing impairment in the 120-240 Hz range (not related to 120 vs.240 volts) and very few people have impairment in the 60-120 Hz range. It is the higher, treble overtones (10000-20000 Hz) and then treble (5000-10000 Hz) ranges that are lost as folks grow older.
 

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Very Stable Genius
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Electrical rooms hum.
Only solution will be to move.
Possibly the building manager would be willing to help you relocate
within the building...unless (s)he has decided you're someone who'll
always be unhappy about something.
The fact you got access to the electrical room and took pictures would
not impress me if I were the bm....unless of course the bm arranged
that.
 

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I've never heard an electrical room, switchgear, or panel boards hum, even with "loose connections", without a transformer or contactors present
Have you ever been near any of that equipment? Press your ear to even a lightly loaded home panelboard and you'll plainly hear it humming away. No transformer required. Turn on significant loads and you'll hear it farther away. Higher current equipment hums even more loudly. It's something unavoidable with AC.
 

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I wouldn't do anything on your own cause of the liability as many others have noted.

That said, perhaps you can discuss with your landlord to let you put in some rockwool in the ceiling / floor to help cut down the sound? I suspect he wouldn't pay for it, but it might be worth the cost to your ability to get a good nights sleep. Don't forget air sealing holes though.
 

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Without going into a long technical explanation, this is normal. Everything in electrical vibrates, even the wires in your apartment / home; it is just so small you cannot see it. Current is changing direction 60 times every second and in a large distribution that is amplified by the 1000’s of amps passing through that equipment.

This is why electrical maintenance is important; equipment with high current must be maintained on a regular basis to prevent loose connections. Connections must be torqued to manufacturer’s specifications and attaching hardware must be changed if it cannot meet the specifications.

Now I am not saying that if the MCC / MDC has some maintenance done it will eliminate the “humming” (because it won’t), but it may be time for some maintenance regardless if the “humming” is that bad.

Cheers
John
 
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