Why is my light buzzing?
December 1, 2012 3:00 PM   Subscribe

Last week my boyfriend replaced the wall mounted sconces in our living room. Today one of them is buzzing intermittently - it sounds sort of like it has a fly caught in it. There is no fly in it. I have taken out the light bulb. I have flipped the switch in the fuse box in the basement that powers this light. It is still doing it and it is freaking me out! Any idea what is going on and if it could be dangerous? I will be out for a few hours tonight and then will be alone in the house till very late and would rather not have a fire start in my living room wall.

Additional info:
The house is old (built in 1930) and originally had tube and knob wiring, but everything appears to updated.
I'm fairly sure that the sconce that we replaced was put in sometime in the last 20 years and has always worked fine and ner made noise.
It is on a dimmer switch.
The other sconce is not buzzing.
It buzzes if the light is on, if the light is off, if the light bulb is taken out and if the power is off.
The if the light is on when it is buzzing, the light does not flicker.
The buzz comes and goes and it really inconsistent - no pattern, not steady.
I first heard it this afternoon, but I don't spend a ton of time in the living room without the TV on, so I guess it could have been going on for a few days.
However, I'm fairly certain it wasn't doing this last Saturday.
We bought the sconces at Lowes - I believe the wiring was very simple (I wasn't here for the installation)
posted by Sabby to Home & Garden (16 answers total)
If you've turned off power to this light, it seems unlikely that the noise you're hearing is coming from the light. You might also want to turn the power off and check the wiring with a multimeter to assure that there isn't a glitch in the system that is allowing power to that light when the fuse is off.

You might also want to try replacing the dimmer switch with a standard switch and see if that makes a difference.

I am not an electrician.
posted by HuronBob at 3:10 PM on December 1, 2012

The previous owner of my house occasionally miswired things. One of the issues was a light hooked up to a dimmer switch that could not, in fact, be hooked up to a dimmer switch, with similar buzzing reslts.
posted by thomas j wise at 3:14 PM on December 1, 2012

Is is a straight-to-mains bulb you're talking about here, or something with a ballast or a transformer? If you've got a light fitting with a built-in transformer, it's probably that that's buzzing rather than the bulb.
posted by pipeski at 3:15 PM on December 1, 2012

1) If you are SURE that the circuit you are turning off at the panel is the one for this light (because with it off the other light won't work);
2) You are SURE that the wiring in the house is done correctly, i.e., no shared neutrals, no missing grounds
3) Turn ALL breakers off and then the MAIN breaker for the whole panel
The light still buzzes - it's not an electrical problem but a magic buzzing fairy;
The light does not buzz;
Turn on the MAIN breaker with all branch breakers off
If the light buzzes: You have a massively dangerous problem - at least once circuit is not protected by a branch breaker. Turn the MAIN OFF and get an electrician out immediately. This is a "oh shit! run around like my hair is on fire" problem.
With the MAIN ON and all branch breakers off the light does not buzz, then
Proceed to turn branch circuits on one at a time - checking for buzz after each one
You find the one that causes the buzzing note which one it is, turn it and the one that should feed the lights off and call an electrician. At this point you are safe as long as those 2 are off so it's not an immediate crisis. But note what is powered by the branches you now have off. If it's the frig, get an extension cord to keep the food cold until you can get an electrician out.

From what you are describing I bet you have improperly routed neutral returns which is not likely to cause a fire but is most certainly NOT safe.

LOTS of knob and tube houses have had romex or other structured cabling added willy-nilly without a real over all plan.
posted by BrooksCooper at 3:18 PM on December 1, 2012 [8 favorites]

One possibility is that there is a loose connection somewhere which is causing sparking - that you hear as the buzzing. Another possibility is that the dimmer switch is causing the buzzing because it is overloaded or damaged in some way. In either case check both the fitting and the dimmer to see if either smells of burning. If you can open them up then you can also look for scorch marks. Check the wattage of all bulbs on the circuit and make sure, if possible, that the dimmer is marked up to be able to take at least this load.

Check also for the type of bulbs in the fittings. Some type of bulbs are not designed to be used with dimmers.
posted by rongorongo at 3:18 PM on December 1, 2012

Any chance it's the fixture physically rattling against the wall? The inconsistency could be that it only rattles when there's low frequencies like a passing truck or footsteps in another part of the house.
posted by Benjy at 3:45 PM on December 1, 2012

I'm going to assume that you have correctly identified the source of the buzz as coming from or near the sconce.

While anything can happen the time correlation between sconce installation and buzzing occurrence strong suggests the installation is the problem rather than some pre-existing problem with your wiring. You should keep in mind the possibility but we'll discount it right now to concentrate on the more likely.

We know this isn't a problem with the bulb because you have removed the bulb and the buzzing persists. Because the buzzing still happens with the bulb removed it's probably not a dimmer problem either.

Ideally turning the switch off at the wall that controls the light should remove all power from the fixture. This is really easy to screw up though.

If the bulbs aren't standard Edison medium base screw in light bulbs (IE: if they are low voltage, florescent, or induction) then I'd guess an integral transformer buzzing and an improperly wired switch (improper wiring could be somewhere not at the switch location).

If they are just standard screw in light bulbs then the noise could be a loose wiring connection. However for that loose connection to make a pure buzzing noise would be fairly unusual.

If it isn't those two things then there are a bunch of crazy unlikely possibilities like bad internal wall wiring or some weird harmonic.

My approach would be to disconnect the fixture and then see if yo still have buzzing. If not then the fixture was the problem so take it back to lowes. If you do you probably need an electrician.

Make sure the breaker is off before removing the fixture. A no contact voltage tester (Voltic) can be used to safely verify you have no power at the fixture before proceeding.
posted by Mitheral at 4:00 PM on December 1, 2012

The buzz is definitely coming from the sconce. The bulbs are dimmable CFL.
The fixture is this one: Sconce

While I am not 100% on item #2 on the list ("You are SURE that the wiring in the house is done correctly, i.e., no shared neutrals, no missing grounds") I did what BrooksCooper suggested and had no buzzing with the main off (whew!) but seem to have buzzing with one that does not power the light.

So, this does not seem to be a "oh shit! run around like my hair is on fire" type problem, correct? But what does this mean? What is this problem called?

On preview, Mitheral has a good point about the installation - if this is a problem involving 2 breakers why did we not have buzzing before?
posted by Sabby at 4:16 PM on December 1, 2012

So, no - if you have breaker A which should power the light OFF and Breaker B which should be unrelated to the light ON and you get buzzing this is the second scenario I described. As long as you can live with A and B OFF until electrician help then you are in no danger.
Turn them off, wait until Monday (to avoid weekend rates) and call around for quotes.

A problem to be remedied but not a crisis.

If something essential is powered by A or B (like the refrigerator) then get an extension cord to power it over the weekend.

NOT a fire hazard if A and B are OFF
posted by BrooksCooper at 4:34 PM on December 1, 2012 [1 favorite]

AS for why the "no buzzing in prior configuration" - can't explain without more data but if the old lights were not controlled by a dimmer that's likely the change that allowed the symptom to appear.

Most dimmers use some current even in the "off" position. I'm positing that you have cross-connected neutrals and thus some current always flowing through this circuit. A plain old switch would be totally OFF when off and thus would not allow current leak.

Without seeing things and testing that's the limit of prognostication. Glad it's not a "oh god we are going to die" problem. That would ruin your weekend for sure!
posted by BrooksCooper at 4:36 PM on December 1, 2012

The old lights did have the dimmer. I guess we will figure this out more once we get someone out here to look at it. And this house is wired wacky - with the 2 breakers off the entire first floor has no power - except for one outlet in the kitchen (which is useful for keeping the fridge on!)
Thanks for your help!
posted by Sabby at 4:44 PM on December 1, 2012

Good luck!
posted by BrooksCooper at 4:51 PM on December 1, 2012

Please report back what your electrician wants to know. Inquiring minds want to know!
posted by BrooksCooper at 4:56 PM on December 1, 2012

What kind of bulbs are you using? When we changed from incandescent to compact florescent bulbs in a chandelier, the whole thing buzzed if you tried to use the dimmer switch.
(The whole ugly thing is now gone, replaced with a ceiling fan, yay!)
posted by deborah at 6:16 PM on December 1, 2012

I once had a lamp which emitted a buzzing noise every time a particular note was played on a nearby piano. Apparently, it had a resonant frequency which caused some part of it to vibrate against a different part enough to make an audible buzz. Gripping the fixture eliminated the buzz, and adjusting/tightening the glass cover eliminated it permanently.

So maybe there's something, possibly an electric device like a fan or a fridge, which is creating a vibration that resonates with the lamp fixture and makes it buzz?
posted by alexei at 7:56 PM on December 1, 2012

Um, just sayin', a shared neutral is not an indication of an improperly wired house. An improperly set up shared neutral would be a problem, however. Had a master electrician throw in lots of circuits for my home office and workshop when we moved in, something like six circuits, all shared neutrals, passed inspection just fine with an inspector who caught the electrician on a code technicality that they both agreed was a bit silly given the situation.
posted by jgreco at 9:37 PM on December 1, 2012

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