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Buzzing light switches...

IanSn
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Registered: 25-09-2011

Buzzing light switches...

Just noticed that my light switches make a buzzing noise when switched on  Huh
However, this only happens when the new fluorescent bulbs are used - not the old tungsten type, these are fine.
I'm wondering if its because this flat has the dimmer switches (even though they are always turned to full on) - could they be part of the problem?
Curious if anyone knows anything about electrics who can explain this...
maybe it would stop if I got new switches?
10 REPLIES
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Re: Buzzing light switches...

It's not uncommon for dimmer switches to buzz but rather annoying when they do, they normally buzz more when turned down a bit and less on full output but CFL (Compact Fluorescent Lamps, AKA low energy bulbs) require less current than the dimmer is designed to work at so may well increase the noise.
I should point out that dimmers are not really suitable for low energy bulbs and should, ideally, be replaced with standard switches.  I suspect that the dimmer switches may also reduce the life of your bulbs.
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IanSn
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Re: Buzzing light switches...

Thanks  Smiley  I suspected something like that, but don't know much about wiring, etc!  Time for new switches...
cheers,
ian
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Re: Buzzing light switches...

About 15 years ago I fitted dimmer switches in the kids' bedrooms.
They complained about high frequency buzzing but I was unable to hear anything.
Up until that point I thought my hearing was very good. Sad
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Re: Buzzing light switches...

Didn't I read somewhere that dimmer switches are not compatible with fluorescent bulbs?
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Re: Buzzing light switches...

Quite often I have seen on Fluorescent light fitting instructions the words "This light is not dimmable and should not be fitted to any dimmer switching."
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Re: Buzzing light switches...

There are 'dimmable' compact flourescents available but not as widespread as the standards ones.
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Infinity
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Re: Buzzing light switches...

Domestic Dimmer switches sometimes work by "chopping" the 50 Hz (Cycles) mains sine wave into many discreet sections, approximating to a sine wave.
Or by introducing a zero voltage portion into the sine wave
And then varying the duty cycle to provide dimming, but only in an incandescent bulb.
CFL (flourescent) lights work on a clean sine wave, and full voltage, hence the buzzing as the circuit in the switch strains.
This causes the buzzing, depending on frequency of "chopping"
Also, even when fully up, the dimmer switches do not normally output the full mains input voltage (240v), or a clean sine wave, some have a switch when fully up to bypass the dimmer circuit.
I've tried to keep this easy to understand.
See http://en.wikipedia.org/wiki/Dimmer
IanSn
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Re: Buzzing light switches...

Yep, I get it.  Expains why the bulbs don't last very long, too.
Rich
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Re: Buzzing light switches...

Hi,
As I understand it using normal energy saving bulbs with a dimmer may be a fire hazard.  I suggest either replacing the dimmers with ordinary switches, or replacing the bulbs with dimmable CFL's.
Richard
IanSn
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Re: Buzzing light switches...

I'll get the switches replaced as soon as poss.  The buzzing seriously didn't sound right to me! Fire did cross my mind...
Fortunately only two rooms have the dimmers.
Put a couple of olde bulbs in there for the time being.
Makes me think of the halogen standing-light which makes a fine old racket in the plug, and the transformer gets very hot....