Are halogens regarded as low energy?

[Peter Scott]

The government has announced the phasing out of filament lamps. Looking around my house, many of the light fittings will have to be changed due to the larger size and different shape of the new lamps. Spotlights are a particular problem because the low energy lamps are huge compared with what they replace and the fittings are compact. Does anyone know if halogen lamps are going to be approved? They are I think more efficient than normal filament lamps. Replacement fittings using those should be about the same size or smaller. Perhaps the great deep-thinking ones haven't thought about halogens? Is there a discussion document or some other written statement from the government?

Peter Scott

[Lobster]

See other thread "Govt banning lightbulbs.... wot about halogens?" where this is being discussed!

[Andrew Gabriel]

They can be slightly more efficient, or be designed for longer life. Most of the retail halogens are designed for longer life, as that's a marketable feature. Anyone using halogens by definition isn't buying on efficiency, so that's not a marketable feature to those people.

Even the most efficient halogens come nowhere near the definition of efficient lighting used in Part L of the building regs. That requires 40 lumens/watt where efficient lighting is required, and halogens are around half that. Only fluorescent can meet that in residential lighting at the moment. There are LED's which can do

40 lumens/watt, but they're too expensive and too dim for main- stream lighting.

Halogens will be replaced by small high intesity discharge lights. That transition has already happened in the commercial world. The initial cost of these lights hasn't dropped enough for them to enter the residential world yet, where initial cost rather than total cost of ownership is what counts. I suspect that when the Chinese start churning them out, they will become rapidly widespread in residential lighting where halogens are used today.

[John]

I just hope the chavs on the estate nearby can keep their 500watt porch lights with the movement detectors

[Andy Hall]

Are these plug compatible with the existing halogens? What about spectrum and brightness?

[Owain]

There was a WW2 anti-aircraft searchlight on Ebay a short while ago.

4kW. I was rather tempted.

Owain

[Andrew Gabriel]

No. They require control gear like (but different from) fluorescents.

Spectrum is continuous, but slightly spikey. They can be made almost any colour temperature. 2700K (same as halogens), 3500K, and 4000K are commonly available values. Ioannis Galidakis has some spectra here, although they are all more powerful lamps than you'd use indoors...

can be made much higher colour temperature for special purposes. I have a 10,000K one which was designed for lighting tropical fish and corals. I used it to light the garden one Christmas day when it had snowed, and it was an amazing effect. 15,000K and 20,000K ones exist too.

You get around 3 times the light output from a metal halide than you do a halogen for the same power. A possible problem for some home use is that there aren't any as dim as many of the halogens at the moment, but that will be resolved when the demand appears.

[Andy Hall]

Now I know the things you mean. A heat issue as well if the aquarium ones are anything to go by, although those are particularly intense in order to be sufficient for corals.

[Derek Geldard]

You learn something new every day.

You mean a Tungsten Halogen Lamp is not a "Metal Halide" ?

Dunces cap >>

[Andrew Gabriel]

Well yes, but mine's a 250W lamp.

Standard metal halides go down to 35W that I know of, which will be approximately 100W equiv light output, but less heat than a 50W halogen. There might be some lower powered ones now that I haven't come across.

[Andy Hall]

So it seems like the ideal would be something that can be retrofitted to existing fittings or perhaps a ballast/controller that replaces the transformer on low voltage ones. However, I imagine that there could be an RF emission issue if the two are separated, or not?

Otherwise I suppose fittings that have the same hole size in the ceiling would be another way and the control system in behind it.

[Andrew Gabriel]

;-)

No. A metal halide lamp is a high pressure mercury vapour discharge lamp which has a mixture of other metals and halides added to the gases to create a fuller visible spectrum, rather than using a phosphor coating as done by most conventional mercury vapour lamps.

What makes it particularly suitable for replacing halogen reflector lamps is that the arc tube in which the discharge takes place can be quite small, making it a tiny source of intense light, not dissimilar to a filament (better in fact). This sort of light source is much easier to control with reflectors and/or lenses than a large source like a fluorescent tube, which is why fluorescent tubes don't make a good basis for designing small reflector lamps.

Next time you're in a supermarket or furniture store which has been fitted out in the last 10 years or so, take a look at the spot lighting. Chances are it will be metal halide lamps.

[meow2222]

Carbon arc? That would blind them, possibly permanently. A 1.6kW arc with no reflector cause about half an hour of total blindness.

NT

[Derek Geldard]

Oh dear me there's a lot of this about you know.

Presumably they need control gear of some kind. (Not seen any BTW even in such as

BICBW) .

I'll check amongst my old mates in the industry, not that it will change the facts, only re-assure me if I've lost my marbles I'm no worse than they are. Which is something.

:-(

DG

[Andrew Gabriel]

Well I was going to say I don't think anyone's done that yet, but a Google search revealed an MR16 Metal Halide lamp from China, so as predicted earlier, they're already on the ball.

uses a car headlamp arc tube, which means it will be operating as a xenon lamp at switch-on for instant light output, until the mercury and other compounds take over the discharge as they heat up.

What I was actually Googling for and didn't find was that I think I've seen a retrofit for one of the larger PAR lamps in the US which instead contains electronic control gear driving a metal halide arc tube.

No more so than for remoted electronic ballasts for fluorescent lamps. There's usually a max lead length to keep within permitted emissions limits. There is a high voltage starting pulse, which also imposes limits on lead length or it gets lost in the lead capacitance.

I think that will become common. I suspect the availability of much higher colour temperatures than are possible with halogens will be a trigger for adoption, much like it was with HID headlamps.

[Mark]

I don't like to be the first to break it to you Owain but WW2 is over! You don't need one.

mark

[Owain]

Hand't thought about what actual mechanism was used to produce the light.

Still sounds appealing :-)

Owain

[John Rumm]

It does possibly explain why (to my eyes) there is such a disparity between the acceptability of light output from ordinary linear fluorescent tubes and CFL tubes.

The spectra show:

Tungsten is as you would expect not dissimilar from daylight, but with attenuation at the blue end:

regular fluorescent has the occasional non linearity in spectra, but is not a big step away from daylight or tungsten: the CFL is *dramatically* different: guess, depending on where in the spectrum your cones peak in sensitivity to the three primaries, different observers could end up seeing very different results. For example you would only need a small shift in the centre of your blue response to end up "missing" a large proportion of the bandpass limited blue reflection. No doubt creating the yellow/green cast that many complain of.

[Alex]

In message , andrew@a20.?.invalid writes

Welch Allyn have been making such lamps for some years, primarily for the medical market. However, their products are also used in some diving and bicycle lights. Their 10W Solarc lamps feature integrated reflector and separate (unregulated) ballast, designed to run from around 12V, and have found their way into several high-end cycle lights.

[Peter Scott]

So it looks as though there are potential direct replacement lamps that will meet efficiency criteria and have a suitable colour temperature, but not yet. Guess I'd better stock up on enough tungsten lamps to see me through so I don't change my fittings unnecessarily. I am currently (!) experimenting with fluorescents in half my wall fittings to compare light outputs and to get an idea of how the light looks. I'm not impressed. The fluoro light is harsh, even though I use 'warm' ones. And of course I can't dim them, so I have to have lower light levels and then buy additional lights to top up when I need more brightness. Like most people, I'm really keen to cut down on electricity consumption for lights, for the sake of my pocket as well as the environment, but it isn't really satisfactory yet.

Does anyone know what happened in Oz when they changed? Were most people forced to change fittings or did they just put up with glaring lamps sticking out of the top of wall fittings or hanging under lamp shades?

Peter Scott