First I must admit to being a novice. So excuse my stupidity.

I'm planning on putting 7 halogen lights in to my bedroom on a dimmer switch. I've bought the lights I wanted from Wickes but it doesn't say anywhere on the box that they are dimmable. Can I still fix them to a dimmer switch? and would a 500w one do?
hannah

[sbowler]

What type of bulb are they? if they are GU10s then there OK. I have 6 of these in the bathroom on a dimmer and there fine. As long as the total wattage of each bulb doesnt exceed the rated power of the dimmer switch you will be fine.

[SimP]

Can I suggest a quick telephone call to a helpful local electrical supplier such as Mr. Resistor (you can find them in London via google). I got all my lights from there and they're very nice.

[sbowler]

You need a transformer if your using 12v halogens, if you buy the 240v bulbs you just need your dimmer switch. GU10s are 240v.

Thanks guys, think I'll give someone a call.

H

[Johnny Thunder]

Be careful with power ratings on dimmers.
Unless the dimmer specifically states for use with halogen, then reduce the
useable power by 20%.
If you are using 7x50w lamps, then you will be overloading dimmers not suitable
for halogen use.(rated at 500w)

OK. I've put 6 20w Halogen lights into the cieling on a series cicuit with a 150w transformer. The switch is a 60-400w dimmer switch. I've just tried to turn it on and it's not working. What's gone wrong?

[Johnny Thunder]

Without being there, I would say you have wired it wrong.
Could be lots of things though.

[Johnny Thunder]

I am assuming you had a centre light that was working.

[Johnny Thunder]

Hannah, did you originally have a centre light?
If so, how many cables were connected into it?
What colours were the cores? (red and black, or brown and blue)

YAY! just went back and checked all my wiring and I think a connection was loose. I now have working dimmable lights. Woohoo!

[Johnny Thunder]

Thanks for your help. Much appreciated.

[Johnny Thunder]

Can I go and wash the pots now.........

[Nick_UK]

Originally Posted by hannahgibson

First I must admit to being a novice. So excuse my stupidity.

I'm planning on putting 7 halogen lights in to my bedroom on a dimmer switch. I've bought the lights I wanted from Wickes but it doesn't say anywhere on the box that they are dimmable. Can I still fix them to a dimmer switch? and would a 500w one do?
hannah

Theoretically, since halogens are only filament lamps, they should be easily dimmable, but there is a snag. Halogen lamps are designed to run very hot, and this (coupled with some clever metallurgy) enables a very bright filament which does not blacken the glass of the lamp. If you dim a halogen lamp, it will not run so hot, and may not last as long.

[davepuma]

....to get my halogens to dim (using a remote control dimmer from B&Q) I had to change the transformer to an electronic one. It cost me £6 or so from an electrical supplier (trade) and about 1 minute of my time to swap.

[niceguy235uk]

If you install any form of downlight, you must now ensure they are 'fire rated', as when you cut a hole in the ceiling you are, in, effect, reducing the fire rating of the ceiling.

Also, halogen lights are not easily dimmable.

Because of the type of load you cannot just use any old dimmer. It has to be able to cope with transformer loads etc.

You CAN use an ordinary dimmer but you must reduce its rating by 50% and not just 20.

This is why in some homes there are multiple dimmers in one room for the LV lighting.

[Johnny Thunder]

Originally Posted by niceguy235uk

If you install any form of downlight, you must now ensure they are 'fire rated', as when you cut a hole in the ceiling you are, in, effect, reducing the fire rating of the ceiling.

Could you show me the regulation that states this.

Originally Posted by niceguy235uk

You CAN use an ordinary dimmer but you must reduce its rating by 50% and not just 20.

Sorry mate, but that is not correct. Some people will recommend 20%, some
even 33%. If you reduce the working load by 50% you are taking the dimmer
into levels where it is not efficient, and it will buzz.

[niceguy235uk]

If you check with your local planning authority, you will find that any form of downlight installed should now be fire rated. However, this may not be required if you choose to retro fit. But, if you choose to ignore this then so be it. Make sure your smoke detectors work.

Each manufacturers dimmers have to be investigated as they are all different.
For eg: MK recommend that their dimmers can be used without derating, but they only recommend that only 5 transformers per dimmer are used.

I have recently installed a 600W remote dimmer in a customers house that does not need to be derated because it is designed for the max load 50-600W. This also incorporates 14 seperate transformers on the switch.

Dimmers should be investigated VERY carefully. Its not just a case of 'this one will work as its 400W and im only using 350. Many dimmers now incorporate safetly features that will reduce the load or cut out completely if they are over/under loaded or they get too hot, but this is not a fail safe.

As for the buzzing, i have had dimmers in the past that buzz under normal load conditions and not just under-load. Its down to how much you want to spend and primarily on the quality of the dimmer.