Dimmers silent but distribution box buzzes!

[spiritburner]

I've just had the downstairs rewired with new lighting.

In the living room I've got 10 halogen 240v 50w GU10 downlighters & 2 50w tunsten wall lights running off a 2 gang 2 way 400w dimmer & in the kichen/diner I've got 2 clusters of 4 halogen 240v 50w Gu10 lights also running from the same spec dimmer.

The dimmers are silent but if any of the halogon circuits are on the distribution box buzzes!

I'm not up on sparky speak but I'm guessing that the dimmers may be under-rated? Could I be stuck here as I can't find any 2 gang 2 way 1000w dimmers listed anywhere?



Thanks,
Ross

[ZippyCat]

Could you clarify whether the living room and kitchen / diner are 2-wayed together, i.e. are all areas controlled from the same switched circuit.

Generally you can only connect 250W of halogen lighting to a 400W dimmer. Lets presume the living room is isolated, and the lights are equally split i.e. 5 spots and 1 wall light on each gang, you will be running at 6x50W = 300W.

If you cannot source a suitably rated dimmer, have you thought about two 500W dimmers adjacent to each other?

[spiritburner]

Hi ZippyCat,

Thanks for yor reply.

Excuse my ignorance of the subject but I will try & clarify as best I can.

In the living room the 10 halogens are on a 2 way with a dimmer & normal rocker switch. The normal wall lights are 1 way but on the same 2 gang dimmer as the halogens.

In the kitchen there are 2 one way clusters with 4 halogens on each controlled from the same 2 gang dimmer.

Since I posted I've been directed to a site that supplies the 1000w 2 gang 2 way dimmers (at a cost!) & the info there confirms your advice -

"If using standard dimmers for mains voltage Halogen lamps the maximum load should be reduced by 25 - 30% ie a 400w dimmer should only be used for a 250w Halogen load."

This would indicate the living room dimmer is way overloaded but I'm confused by the problem occuring in the kitchen. Each dimmer on the 2 gang is only switching 200w so is the 400w split between each dimmer on the 2 gang ie 200w per dimmer? Given the need for 35-30% load reduction I'm guessing it is.

Cheers,
Ross

[ZippyCat]

It’s a little difficult to identify the cause of the buzzing without seeing the installation, you would be better off getting a spark in assess the problem. At the end of the day if something is fundamentally wrong, it’s your home and family’s lives that are potentially at risk from a faulty installation, something not worth risking. Sorry I couldn’t be of any further help.

Regards

ZippyCat

[Johnny Thunder]

Without actually inspecting and testing the installation,
it sounds like a loose connection in your consumer unit.
There should be no buzzing coming from there.

Johnny.