Halogen myth


We are told that halogen bulbs produce twice as much light as an ordinary bulb for the same power consumption (50 watt halogen = 100 watt ordinary)
we can expect to pay about 5 times as much for halogen bulb for this benefit
I have often treated this claim with much sceptisism since i noticed halogen cycle lamp bulbs claiming the same were actually double the wattage of ordinary vacuum bulb and gobbling up batteries in much less than half the time (no different from doubling the wattage of std vacuum bulb) ????
Anyway - after a new kitchen refit - i just replaced 3 x 100 watt vacuum spots - with 3 x 50 watt halogen spots - i think it's fair to say that far from their claim of being 'as' bright - they are not even half as bright - the kitchen looks positively dull
I will be able to confirm this since i bought another 3 x 50 watt halogen spot - and i intend to take these out and mount them with the other cluster to make 6 x 50 watt halogen cluster
Which leave the questions:
How did halogen bulbs make it onto the market?
Why do people buy them?
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Who is We? And who is telling We? That information on a like-for-like swap basis is incorrect.

Yes, indeed. However, that's nothing to do with the lamps themselves -- it's because the lighting is inappropriate for the purpose for which it's being used. The halogens probably are slightly brighter, but because they have more accurate beam control and less light spillage, they will only be lighting up a patch underneath them. The light level in the rest of the kitchen now depends largely on the reflectivity of the surface with those light patches, which is typically very low. With your previous reflector lamps, the beam control is bad, so light spills all over the place, and gives you a better lighting level in the rest of the room. Both types of light are inappropriate for general lighting in a room, one more so that the other. If you want a room lit well, you need to design (or have designed for you) a auitable lighting scheme.

Halogens work well when used correctly. Using halogen spotlamps for general lighting is usually inappropriate and hence gives poor results in terms of low lighting level and/or high running costs.

Most people haven't got a clue how to design effective lighting schemes, and don't realise they don't have a clue. Also, those lights are usually dirt cheap initial cost.
--
Andrew Gabriel
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writes:

I think Andrew is exactly right. Halogen bulbs run at a higher temperature, they can do this because the quartz of the glass allows it without breaking. The halogen gas is better for longevity than the vacuum - you can't produce a perfect vacuum anyway thus the gas left in will oxidise at high temperatures, deposit oxides on the glass and dim the output. So Halogens produce a whiter light, "brighter" if you like, which is great for throwing the light longer distances.
We did the same - put sunken spots in the kitchen but specifically where they were needed. Typically, normal lamps are usually placed in the centre of a room and then you stand in your own shadow when working at the surfaces or the sink. Equally, large lamps placed at the periphery of a ceiling look pretty daft. The spots ( two over the walkway and 6 over the surfaces ) work brilliantly, giving light to the working area. However, they need to be close enough to each other such that some light overlaps the next spot, which avoids shadowing of your hands and the work. They need to be placed close to the wall so that some of the light hits the wall and reflects downwards too. Even with these 8 x 50 watts the impression remains that our kitchen is dull, but when actually working at the surfaces all is well.
TonyB
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Halogens can be designed to run at a slightly higher temperature, or to have a longer life. In the domestic/retail sector, they are normally designed with longer life, because people won't by a lamp which costs 5-10 times as much and only has the same life, regardless of its other properties.

Ordinary filament light bulbs are gas filled with nitrogen, to slow down the rate of evaporation of the filamant. The only vacuum bulbs are the low powered mains ones (e.g. 25W and below) and the tubular filament lamps, all of which are horribly inefficient.

Halogen lamps usually have smaller/shorter filaments than conventional lamps. The smaller light source makes it possible to design the lamp optics to produce a more controlled beam with less light spill off-beam, and where desired, a narrower beam angle.

Before you start thinking about spotlamps, you need good general lighting in a kitchen, covering everywhere. A very effective way to do this if you have wall cupboards is to use fluorescent tubes hidden on top of the cupboards, lighting up a brilliant white ceiling. The indirect light reflected from the ceiling gives you a good level of illumination all around with no shadows. For intricate work, such as food preparation, washing up, motorcycle engine stripdown, etc, you will probably benefit from task lighting providing a locally enhanced lighting level at the worktops. Under cupboard fluorescents are excellent for this. Spotlamps could be used but won't give you shadowless even lighting. Finally, if you have any features or display areas which would benefit from highlighting, that's what spotlamps are for -- it's called accent lighting. Given the good general lighting already present, you should only need something of the order 10-20W, and not 50W spots. Have the different types of lighting separately switched, which gives scope for boosting outdoor daylight without having to turn on everything, and different mood settings in the evening, e.g. by switching off the general lighting and just leaving accent and/or worktop lighting on.
The last two kitchens I've done have had no lights on the ceiling at all. It's a remarkably useless place to have lights in a kitchen (unless you have an island or table).
--
Andrew Gabriel
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We only have one cupboard, so that wouldn't be an option in our case.
Under cupboard fluorescents

Well I must disagree - if the sunken spots are close enough together as ours are, very low shadow is obtained and even lighting across the work surfaces, largely due to the spots being close to the wall.
Finally, if you have any features or display

Now that's a good idea, I must say we didn't think of directional spots as well. There are a few features that may benefit from some further light such as the Aga and the plate display.
TonyB
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When I changed from a 0.4A @ 6V tungsten (vacuum/ inert) to 0.4A @ 6V halogen headlight on my bicycle about 15 years ago, I found the new light to be substantially better. I didn't do any measurements (or recall any `twice as much light' claims) but my subjective experience was that there was much more and whiter light. Yet the lamps had the same power rating and the dynamo, for the sake of brevity, was not capable of putting a different amount of power through them. The lamps had a much longer MTBF, too, which was counterintuitive. To this day, I'm sticking with halogen until a more efficient alternative shows up which can get close to matching the colour rendering ability of halogen.

My kitchen and bathroom have tungsten spot lamps as downlighters for general lighting. The `spot' is about 110 degrees wide so the type and distribution of the light is not far off that of GLS. All of the halogen lamps I've seen have a much narrower beam and for that reason I wouldn't dream of using them as replacements for the tungsten lamps.
I'd wager that if you lay on the floor directly in line with your halogen lamps, you'd find them very bright. As Andrew Gabriel says, that's only useful for general lighting if you point them at something reflective/ emissive.

... Fools and money? Or for people using them in applications where a narrow beam is called for. I've never been able to understand why someone doesn't make a genuinely wide beam version of them (much wider than the ones currently described as `flood' lamps), though.
--
Mark

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You should switch over to pre focused lensed Luxeon LED bulbs
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and run. The illumination quality is also dubious. I have a decent sized kitchen and all I have is a 5' fluorescent on the ceiling, a small fluorescent under a worktop and a light on the cooker. The overall illumination is perfectly adequate and cheap to run, unless you want to perform a surgical operation on the kitchen table!
Terry D
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