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Humming Dimmer #75651
03/07/07 10:56 PM
03/07/07 10:56 PM
Happi_Man  Offline OP
Joined: Jun 2002
Posts: 206
Columbus, Ohio - USA
I have my theory but I am wondering what your first guess would be as to why a dimmer switch makes a humming sound (obviously when the light is on). How do you explain this to a homeowner?

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Re: Humming Dimmer #75652
03/07/07 11:01 PM
03/07/07 11:01 PM
HCE727  Offline
Joined: Nov 2005
Posts: 186
Delaware County, PA, USA
Check out

Re: Humming Dimmer #75653
03/07/07 11:51 PM
03/07/07 11:51 PM
JoeTestingEngr  Offline
Joined: Nov 2005
Posts: 791
Chicago, Il.
I think it is the standard answer: It doesn't know the words! The more the delay towards 90 degrees, the greater the harmonics / noise caused by the triac switching. This is in the audible spectrum. Snubber circuits are used in the output to reduce noise. I would expect that most of the noise you hear at the dimmer comes from the iron cored inductor of the snubber circuit. Think of the noise you hear coming from power transformers with some harmonics mixed in.

Re: Humming Dimmer #75654
03/08/07 01:59 PM
03/08/07 01:59 PM
SteveFehr  Offline
Joined: Mar 2005
Posts: 1,213
Chesapeake, VA
Explain to them that there are coils of wire in the dimmer just like the coils in a speaker, and the fluctuating magnetic field makes it vibrate and hum a small bit.

It's not completely accurate, but should make them feel better.

Re: Humming Dimmer #75655
03/08/07 03:46 PM
03/08/07 03:46 PM
noderaser  Offline
Joined: Mar 2007
Posts: 404
Portland, Oregon, United State...
We also get hum from the lamp filaments, in our theatrical fixtures. Most newer lamps are designed to prevent this, but replacing all of our fixtures to work with newer lamp designs isn't cheap. Not sure if this is a problem with smaller bulbs (assuming 100 watt or less).

Re: Humming Dimmer #75656
03/08/07 08:41 PM
03/08/07 08:41 PM
HLCbuild  Offline
Joined: Dec 2004
Posts: 209
Herndon,Va USA
All those things that Joe said...and cheap light bulbs. I used to have the same problem. The dimmer has a filter to keep the bulbs from humming. So now the dimmer hums. Upgrade your light bulbs.

Re: Humming Dimmer #75657
03/08/07 09:58 PM
03/08/07 09:58 PM
Scott35  Offline

Broom Pusher and
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
I was going to add what "noderaser" mentioned, but not needed now!

Looks like Lighting is more oriented towards the Entertainment Industry than previously expected, in that we have...

Singing Lamps and Humming Dimmers

Just couldn't resist that one! [Linked Image]


edited to fix UBB coding blunder!

[This message has been edited by Scott35 (edited 03-08-2007).]

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!


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