Dimmer switch

abc123 · 13 Dec 2004

I have a 4 dimmer switches in my house and 3 of them are working fine. One of them works intermittently ie sometimes the 7 lights come on and sometimes nothing. I can try the next day and it works and then the day after doesn't. It's driving me mad. When they do work they can take 2-3 seconds to come on or half the lights come on immediately and then after 2-3 seconds the rest come on. I have been in the loft and moved the insulation so it doesn't cover them, which I thought may be the problem but unfortunately it doesn't fix it.
I have tried a different dimmer switch but that doesn't fix it , can anyone offer any advice please before I go completely insane.

breezer · 13 Dec 2004

bad connection?

securespark · 14 Dec 2004

Got toroidal tx's? Sorry, transformers?

alertelec · 14 Dec 2004

Yes, if its not the dimmer and not the connection, but all of the lights come on if they are going to then it would point to the transformer whether toroidal or electronic. This assumes that you have one transformer feeding all of the lights?

If you have a meter you could check the primary side and the secondary side (supply & load) of the transformer for power.

abc123 · 14 Dec 2004

Thanks for the suggestions. There is a transformer put in for each light fitting.
Not sure whether to replace the transformers for better or more powerful ones. Does anyone know how much a meter costs to check the supply and load?
Thanks

alertelec · 14 Dec 2004

If there is a transformer for each light fitting then it seems unlikely that all the transformers would be at fault. You have already been in the loft and moved the insulation, so this should stop the transformers tripping out on thermal overload.

You mentioned that you have seven lights. What is the size of the lamps in them and what is the maximum rating of your dimmer switch?

abc123 · 14 Dec 2004

The lights are 40 watt each but I don't know how to check the max rating of my dimmer switch
Having looked on the web I've found something that talks about intelligent dimmer switches, will look into this as well.

alertelec · 14 Dec 2004

I am not familiar with any low voltage lamps that are 40w , the common sizes are 20w, 35w, 50w.

The rating of the dimmer should be printed on the back of the dimmer module. The intelligent dimmer has a soft start and overload built in I think.

Irrespective of the dimmer used you should not exceed the maximum stated and with low voltage you should consider de-rating the dimmer by 25%. This is the reason I am trying to find out if the maximum wattage has been exceeded on the dimmer.

abc123 · 14 Dec 2004

I stand corrected I was trying to think back to when they first went in and I knew they were around the 40 watt, they are in fact 35w. So 7x35.
So if I've understood correctly what I need to do is check the rating of my dimmer and if it is less than 7x35 = 245 get it changed or get an intelligent dimmer.

alertelec · 14 Dec 2004

Assuming that this is the problem yes, I am stabbing in the dark until we know exaclt what the dimmer is. It may well yet turn out to be a loose connection

To be on the safe side de-rate it by 25% so the minimum should be 330w so you will need a 400w dimmer. Make sure that it is compatible with the transformers that you are using, most transformer and dimmer instructions say what they are compatible with. Generally, most electronic transformers are compatible with most dimmers.

abc123 · 14 Dec 2004

OK, thanks very much for your help, now I know where to look if/when I've fixed the problem and it maybe I do it after Xmas I will post to this message board to let you know the solution for future reference. Cheers

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Dimmer switch

breezer

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