Which 2way dimmer to operate 15 mains halogen spots?

[Corrado]

I want to have 15 mains dimmable sunken spots fitted in my kitchen and want to control them from a 2 gang dimmer switch.

The 15 lights will be split into 2 sections in the kitchen. 1 Switch will operate 8 lights and the other will operate 7 of them.

The trouble I am finding is that the switches I am finding seem to be 2 way 2 gang 250W switches.

Does this mean that I will be overloading the switches? I may be wrong, but I have taken the theory that each light is 50w and 50w x 8 = 400w.

Do I therefore need a 2 gang 400w switch? Or, is the 250W rating for something completely different?

Any advice much appreciated. Also looking for brushed chrome 2 gang dimmers, which I imagine is narrowing my market further.

 

[breezer]

give up now.

most dimmers have to be de rated for halogens.

eg dimmer says
" 500w dimmer switch, must be de rated by 50 % for halogen use"


so that means the 500w dimmer is now only a 250w dimmer.

Thing i don't understand is why fit so many halogens and then dim them?

halogens by nature work best when not dimmed

 

[the_jinj]

Might be best to split them into alternate lights controlled by a 2 or 3 gang switch instead of using a dimmer?

 

[Corrado]

kitchen designer has put so many spots because the kitchen is very large and he says that by their nature, halogens are not very directional.

If I just go with LOW VOLTAGE lights, will I overcome this problem? I have been told that Low Voltage lights aren't dimmable, but is the advantage that you can use more lights?

 

[Corrado]

If I don't bother dimming them, could I get myself out of this problem!?

Are conventional light switches not as restrictive?

 

[Steve]

low voltage use the same amount of electric as mains voltage, lets clear this up right now!

for a kitchen, I would always recommend fluorescent fittings. Very good light distribution. Halogens are too directional, and very inefficient.

 

[Corrado]

I want to use halogen and I don't mind whether I use mains or LV - would I be better off with LV, then if I stick to using conventional rocker switches?

Also - is the maximum wattage thing only an issue with dimmer switches?

 

[Adam_151]

kitchen designer has put so many spots because the kitchen is very large and he says that by their nature, halogens are not very directional.

Bah!, designers, yeah not that directional and need quite a lot of them, so an inefficent way of lighting, I mean 750w of lighting in a domestic kitchen , not going to be good for your electricity bill, or the lamp replacement costs, at least they are PAR lamps though which means the heat goes into the room (rather than dichroic which throw the heat into the ceiling void)

Whats wrong with florescent strip lights 120W of will light a large kitchen without shadows and dull areas all over (I replaced 360w of R63 spot lamps with 120w of florescent light, and the illumination is much better

Favourite quote of mine at the moment (I'm applying it to everything!):

“Reality must take precedence over public relations, for Nature cannot be fooled.”

- Richard P. Feynman[/quote]

Your designer is trying to design a fashionable kitchen with very little thought for other concerns

Also remember that fashions change, a few years down the line these lights will be seen the same way as shag pile carpet and syrofoam ceiling tiles are today (and the R80 lamp varients are already seen that way), and when the time comes some poor bugger is left with a hole in the ceiling to do something with

If I just go with LOW VOLTAGE lights, will I overcome this problem?

Not all all, though you will get slightly more lumens per watt (but the waste heat won't even warm the room, for they are dichroic lamps)

I have been told that Low Voltage lights aren't dimmable

Incorrect, but you do need suitable transformers and dimmers
[FWIW: technically 'low voltage' is mains, and what you term as LV is really 'Extra Low Voltage' and in the case of lights will be 'SELV'*]

but is the advantage that you can use more lights?

A 50w SELV lamp will consume the same as a 50W mains lamp, you can have as many as you want of either providing your switch gear and cabling is upto the job

I'd recommend switching them in banks as opposed to dimming (if you insist on using them!), while dimming does reduce the amount of power taken, the efficency drops off until which point you have power heating the lamp and but its not hot enough to emit any light, I expect this is worse with halogens as they run hotter than normal lamps, also running them cooler as well as being less effcient in terms of %, also disrupts the halogen cycle, reducing lamp life

Sorry for the negativity, but thats how it is, they might look nice (at least ATM) but other than that, these fixtures are a load of rubbish




* Separated Extra Low Voltage - low voltage with no reference to ground

 

[Steve]

Maximum wattage is an issue with dimmers - you can overload the electronics in them. Its a bit like a variable resistor - it will overheat and burn out if you try to pull too much current through it.

A switch, on the other hand will usually take up to 10 amps - the maximum for most lighting circuits. Though if it is switching close to 10 amps, its usual for it to spark when it is breaking the current.



As an aside, is it POSSIBLE to fit recessed modular ceiling fittings into a normal plasterboard ceiling? You know the type - 4 fluorescent tubes in rows, either 2 foot or 4 foot long. These would look better than ordinary single or dual tube fittings.

 

[RF Lighting]

Right. I've had a bit of a thought. Your proposals could be achieved with a bit of modification to the design. As you now know the loads that you intend to have are too high for the dimmers you propose to use. There are a few soloutions for you to have a think about that will over come the problem.

1) Split the lights onto more switches
2) Install less lights.
3) Use a standard light switch
4) Use two 1000W dimmer switches mounted side by side.
5) Install a scene setter. (this is a nice bit of kit, that would solve the problem but it is very expensive)

I think your best (and easiest) option is to install two 1000W dimmers like these into a box like this

It is not the best looking option but it will do what you want without having to redesign the circuit.

I have been told that Low Voltage lights aren't dimmable

Low voltage lighting is dimmable. It used to be a problem years ago when folk were installing the old torroidal wound transformers which required special dimmer switches, but the new electronic transformers are fully dimmable with standard (derated) dimmer switches.

Personally I would install low voltage down lighters, but the pros and cons of LV & mains downlighters have been discussed in here loads of times, and in the end it comes down to personal preference.

 

[Corrado]

Thanks so much for this, I really appreciate it!

How about:

I get rid of the dimmer idea and have a 2 gang switch and split the room into less lights, 6 on one side and 4 on the other?

As long as I am clear that getting rid of the dimmer will sort my problem, right?

Is the biggest benefit of LV lights the fact that they last longer? I have mains ones all round and have never had any trouble with them blowing, they last about 18months.

 

[RF Lighting]

You can either install the 1000W dimmers or fit a standard 2 gang switch without having to remove any of the lights. If you do away with the dimmer there should be no problems, and if you find in the future that your kitchen is just too bright you could always install 35W or 20W lamps.

There is no real difference in the life of 12V or 240V lamps. just better crisper light of the 12V lamps. At home I fitted some 240V GU10s about 4 years ago which are in daily use, and one of the lamps is still going (the oters lasted about 2 years), and fitted some 12V lams about 2 years ago, all of these are still going) Aslong as you fit a decent quality branded lamp (not supermarket own brand) than lamp life should not be an issue for either lamp type.



(all my downlighters are on soft start dimmers)

 

[Adam_151]

What about one of these: http://www.tlc-direct.co.uk/Products/VLIC1403.html

4 lights on each channel, would have to loose 3 lights though (or push it a little with 5 per channel... you are not exceeding the real rating.. but the guideline to stop it blowing when it 'starts' the lamps from cold, but thats not really adviseable )

Or dual gang box, dual 400w on each side, 4 lights per channel (space for one extra light)

Or just do as you say and ditch the dimmer, and have many different banks, you can get a double plate with 6 switches on it

Just OOI, who is wireing these lights? yourself? or are you having an electrical contractor install them for you?

 

[RF Lighting]

Or dual gang box, dual 400w on each side

Use two 1000W dimmer switches mounted side by side

 

[Corrado]

great, thanks - will go for a 2 gang switch and ditch the dimmers!

I am having an electrician wire it all up for me. I am amazed he did not bring this to my attention...