Halogen Spots 12v vs Mains?


I'm having some (12 or so) new halogen spot/down lights fitted and I'm trying to choose between 12 volt or Mains
A few years back 12 volt spots started to emerge on the basis they used much less power and produced the same light - i was never really convinced by this
I notice you can also buy 240v halogen spots now - in fact i notice Wickes don't seem to stock 12 volt at all
I'm looking for pro's and cons?
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Power (watts) is volts x amps. If it's a 60 watt bulb, then it uses 60 watts if it's designed to accept 240 volts and it uses 60 watts if it's designed to accept 12 volts. So it's the same.
But if they are LEDs then it's a different story. These give out light in a different way to incandescent bulbs and use less electricity.
But someone may come along and refute all this.
Rob Graham
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A 60W LED uses 60W. At the moment LED lighting is useless apart from decorative effects. I assume you mean CFC lighting. CFC lighting is more energy efficient but not everyone likes the colour spectrum or slow warm up time for these lamps. A CFC lamp should use about 1/4 of the power of a incandecent for the same illumination.
A 12V halogen should use more power than a 230V halogen as there are transformer losses to take into account. This would only be about a 1% loss. However 12V halogens last longer than 230V versions and give a whiter light. The original cost of installing 12V halogens is soon recouped by maintainance costs.
One other point is that halogen spotlights are no use other than for spot lighting. Ie you cannot light up a lounge or bedroom properly with these but one placed above a computer keyboard, shower or mirror (for example) may be usefull.
Adam
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ARWadsworth wrote:

Well... yes... but...
Many low power bulbs (CFL and LED) are marked with the wattage of an incandescent of equivalent light output. So the two CFLs I have in here are "100W equivalent" but actually 18w. And quick dig on Maplins finds
http://www.maplin.co.uk/module.aspx?ModuleNo5331&doy#m9#overview
LED bulbs rated at 1.8W but with a power output "approx equivelant to a 20 watt dichroic." (sic) This makes them 11 times more efficient, so a 60w LED unit would be putting out equivalent light to a 650W incandescent. Unless you're doing stage lighting, you probably don't want that much!
Andy
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That is CFCs not LEDs. You really need 22W CFC to meet a 100W incandecent.
And quick dig on Maplins finds

That is in the FAQ not a spec sheet. They are not 11 times more efficient.
Unless you're doing stage lighting, you probably don't

One of these LED lights would not give enough illumination to light a small toilet. Try a LED torch if you do not belive me.
Adam
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ARWadsworth wrote:

Adam, Both you and Andrew have rubbished the LED lights. I have tried an LED torch - I have one in my phone, for example - and I've seen a lot of pushbikes with LED headlights. I imagine they use them because they are more power efficient - but I don't know. I've never tried anything bigger.
Do you have any links to anyone who has done a proper comparison?
White LEDs BTW are IIRC a fluorescent technology.
Andy
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A torch is a good use for LED lighting as you expect a very narrow beam to concentrate the limited light output into a small spherical angle. When you try to do this with a filament lamp, you get losses at the reflector surfaces, and wasted spillage outside the desired beam.

Any LED manufacturer's datasheet gives you the lumen output at the rated operating current. Torches usually overrun the LEDs as no one expects more than around 10-20 hours life from a torch. A cycle lamp may do this but probably to a lesser extent.

Yes indeed. The phosphors lose around half the light energy just as with fluorescents (one UV photo in becomes one lower energy visible photon out + heat). Also, the phosphors steadily decline in efficiency with age just as they do in fluorescents.
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Andrew Gabriel
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For what it's worth - i used to sell LED lights when they first emerged for use on bicycles (a squillion years ago)
Pro's - LED's where all but indestructable - Ran virtual on vapour - e.g a conventional bulb consumed conventional batteries in about 2-3 hours - it took LED's several days to consume batteries - they use such little power that i actually remember some guy running one off a potato (any veg or fruit containing acid)
Con's - Couldn't be used for front lightinting because they simply did not give out enough light (you could be seen but you couldn't see)
Whilst they may have come a little way since then - i can't imagine the pros/cons have changed that much
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Yes they can, although you have to stay within the load range of the transformer. Electronic transformers will have a wider load range as they include feedback to maintain the correct output voltage.

I've never had one fail. Make sure you put them somewhere where they are well ventilated so they don't get hot.

Low voltage ones are significantly more efficient. However, you can get ones with differently rated lives and the longer lived ones are less efficient, so this is also a factor.

12V are cheaper to run by a lot. Mains are cheaper to install.

Neither -- downlighters aren't appropriate for general lighting in a kitchen (or anywhere). They are for task lighting and accent lighting. They are horribly inefficient and ineffective for general lighting.
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Andrew Gabriel
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Not a chance. A 100W incandecent lamp can light one room. 2 x 50 halogens cannot light the same room. They create pools of light.

How told you that? Electronic and torriodal transformers are dimmable.

I prefer individual transformers. At 3ish they are not expensive to replace but seldom fail. I have 4 and they have been in use for over 8 years. I also have swapped 3 lamps in the same time period.

12V is brighter and whiter

12V is cheaper as 230v halogen lamps blow frequently

12V lasts a lot longer

A flourecsent on top of the wall units to light the room up and 12v halogens dotted around over work surfaces to keep SWMBO happy.
Adam
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bit brighter - twice as bright? - i think the time must have come where manufacturers should rate lighting by how much light it gives - maybe lux measurment - otherwise we really are fishing in the dark

i dont follow - i thought 50 watts was the power consumption (whether mains or 12 v)

so i scrap the plans for 12 spots built-in to the ceiling (just to find out i can't see a thing) and go back to flourescent tubes as main lighting?
i currently have 3 x 100 watt non-halogen mains spots in old kitchen and it's much nicer/brighter than the old flo-tube albeit it 3 times more expensive to run
electrician is pressing me for an answer so i think it's back to conventional bulbs until i do some more research
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12v just gives a whiter crisper light.

Cheaper maintainace costs. Not the electrical running costs.

Under cuboard lighting is excellent.
Adam
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This is more to do with the design life of the lamps than the voltage. Short life ones run at a slightly higher temperature (resulting in your whiter crisper light), which also makes them more efficient. Longer life ones do this by running at a slightly lower temperature. There's probably a wider range of design life available in 12V ones (think I've seen 1000h, 2000h and 5000h in datasheets), but normally you get no choice when they've got as far as the retail outlet which just buys one type, and usually the packaging doesn't say which. I don't think mains ones of less than 2000h are easily available, as people would baulk at the high price for only 1000h life (which is barmy as the electricity price swamps the lamp price).
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Andrew Gabriel
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