Dimmer switch very hot

[Gherkin]

I bought a metalic double dimmer switch from Homebase for an electrician to install but he said it was not suitable for the load (6 low voltage lights on 1 switch and 7 on the other). He installed a different dimmer switch.

The trouble is the lights don't dim all the way down and the plastic covered plate is EXTREMELY hot. To the point that you would burn yourself if you touched the plate for more than 2 seconds.

It all looks (and sounds) extremely dodgy.

Has this happened to anyone else before? Do you get different dimmers for different loads? I didn't notice any in Homebase but can't say I really looked. I suspect the transformers are not dimmable as one of the downstairs lights flickers if dimmed.

Will the hot plate cause any damage to the original wiring?

 

[breezer]

i would favor your idea you do not have dimable transformers, change one or the other, asap

yes dimmers are rated differently

 

[ban-all-sheds]

The trouble is the lights don't dim all the way down

That's because you are not supposed to dim 12V lights all the way down - it bvggers them up.

I suspect the transformers are not dimmable as one of the downstairs lights flickers if dimmed.

RTFM, eh?

Will the hot plate cause any damage to the original wiring?

If it's as hot as you describe then it could easily do so. Get this sorted asap.

 

[Gherkin]

Thanks for the replies

When you say 'bvggers them up' what do you mean? The lightbulb, light fitting, transformer or dimmer switch (or everything)?

As soon as I can get hold of the estate agent I will get it sorted.

I 'installed' a single dimmer switch in a bedroom which presumably has similar wiring to the rest of the house. The buzzing from the switch is noticably lower than the one installed in the lounge by the sparky. Also, I can dim the (4) lights to blackout without a problem. It appears as though there isn't a problem but if, as you say, the lights should not dim all the way perhaps there is

Finally, what sort of things could happen if the situation is left as is. Worst case is obviously plate overheating and causing a fire and burning down the house. But on a less dramatic scale?

You may have guessed - this is not my house. All of this has been handled by an estate agent and his contractors who probably charge the landlord for the priveledge so it's not really down to me to RTFM!

I just reckon the landlord should be made aware of the incompetent cowboys working for him...

 

[ban-all-sheds]

When you say 'bvggers them up' what do you mean? The lightbulb, light fitting, transformer or dimmer switch (or everything)?

The bulbs - halogens don't like running at low voltages, as the processes designed to go on inside them stop working, and their life is shortened. I thought that maybe the electrician had chosen a dimmer which was designed not to go all the way because of this fact.

Finally, what sort of things could happen if the situation is left as is. Worst case is obviously plate overheating and causing a fire and burning down the house. But on a less dramatic scale?

Worst case is unlikely, at least, not immediately. Wiring insulation is designed to be OK at 70C, which is pretty hot to touch. I guess it shouldn't come to any harm at that temperature. Between "OK" and "bursts into flames" there is a zone where plastics will become brittle, and over time you risk them disintegrating, so although you need to get this sorted asap, I doubt if you need to worry that you're going to go up in smoke if the guy doesn't come for a day or two.

Is there a buzzing when the lights are on full?

Does it only get hot when dimming?

Is there a smell of burning coming from it?

You may have guessed - this is not my house. All of this has been handled by an estate agent and his contractors who probably charge the landlord for the priveledge so it's not really down to me to RTFM!

Sorry 'bout that - thought you'd chosen the lights...

 

[Gherkin]

Is there a buzzing when the lights are on full?

The double dimmer installed by the 'electrician' does buzz when the lights are on full (although full seems to be less bright than before the dimmer was installed) but at something I would consider normal/acceptable level. The buzzing increases the dimmer you get which, again, in my limited experience is usual.

Does it only get hot when dimming?

It seems to get hot whenever the lights are on but only excessively when lights are dimmed.

Is there a smell of burning coming from it?

Thankfully there is no burning smell - yet!

Is there any chance of 'melting' or 'frying' the transformers or wiping out the main fuse box because of the dimmer switch?

 

[kendor]

I bought a metalic double dimmer switch from Homebase for an electrician to install but he said it was not suitable for the load (6 low voltage lights on 1 switch and 7 on the other). He installed a different dimmer switch.

The trouble is the lights don't dim all the way down and the plastic covered plate is EXTREMELY hot. To the point that you would burn yourself if you touched the plate for more than 2 seconds.

It all looks (and sounds) extremely dodgy.

Has this happened to anyone else before? Do you get different dimmers for different loads? I didn't notice any in Homebase but can't say I really looked. I suspect the transformers are not dimmable as one of the downstairs lights flickers if dimmed.

Will the hot plate cause any damage to the original wiring?

Sounds like one half of the triac has gone and shorted. hence you can't switch the lamps off fully and they don't reach full brightness due to the the fact that the triac is now a thyristor and you are getting only half wave output, this is almost certainly due to you trying to dim an incompatible load check that you have a transformer compatible dimmer next time you buy one.

 

[securespark]

Why all the talk of "don't worry, you won't burn the house down just yet"??

Why not just stop using them until it's sorted? Is it a real hardship to do without lighting in one room until it is fixed?

 

[ban-all-sheds]

Or just put an old-fashioned on/off switch in until the dimming can be sorted....

 

[Gherkin]

Thank you for all your words of wisdom.

I may be female but I am not completely stupid!

I have not used the lights since the problem was detected. I merely wanted to gleen some knowledge to pass onto the landlord about his expert agents and contractors...

 

[securespark]

I wasn't implying stupidity, and your gender is irrelevant!

I just wondered why people were talking about the chance of overheating as slim, suggesting that you might carry on using the light, or at least implying that if you did you would come to no great harm, when the best course of action with a dicky circuit is to stop using it!