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#1
Old 04-23-2015, 04:58 PM
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How hot do halogen light bulbs get?

I have a couple of vintage designer lamps that are rated for 60W light bulbs, probably because the plastic in them is heat sensitive. Since I am running out of traditional incandescent bulbs I was thinking of switching to halogen bulbs, but I hear they run very hot. The question is how hot do they get really? I have bought 46W halogen bulbs that are supposed to give the equivalent light of 60W in old style bulbs. Are these ok to use for my purposes?

(I know there has been a lot of threads about light bulbs, but I don't think this exact question has been adressed)
#2
Old 04-23-2015, 05:42 PM
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The external envelope in a halogen incandescent-replacemnt lamp gets no hotter than the incandescent it replaces.
Probably cooler, since it's only 46W vs. 60W
#3
Old 04-23-2015, 06:24 PM
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Quote:
Originally Posted by beowulff View Post
The external envelope in a halogen incandescent-replacemnt lamp gets no hotter than the incandescent it replaces.
Probably cooler, since it's only 46W vs. 60W
While it is true that the total heat dissipated at equilibrium is the same for any 60W bulb, it doesn't necessarily follow that they are at the same temperature. Halogen bulbs usually have a much smaller surface area than the equivalent normal incandescent bulb so that area must be at a higher temperature to radiate the same amount of energy.
#4
Old 04-23-2015, 06:24 PM
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Thanks! That's what I thought. Makes me wonder why they always warn about the heat in halogens when they make comparisons. Perhaps it's only those small, spotlight things that you have to worry about.
#5
Old 04-23-2015, 06:29 PM
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Quote:
Originally Posted by leahcim View Post
While it is true that the total heat dissipated at equilibrium is the same for any 60W bulb, it doesn't necessarily follow that they are at the same temperature. Halogen bulbs usually have a much smaller surface area than the equivalent normal incandescent bulb so that area must be at a higher temperature to radiate the same amount of energy.
My halogen bulbs look exactly like traditional bulbs so I guess I should be ok. Unless most of the heat goes to the socket.
#6
Old 04-23-2015, 07:24 PM
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Quote:
Originally Posted by leahcim View Post
While it is true that the total heat dissipated at equilibrium is the same for any 60W bulb, it doesn't necessarily follow that they are at the same temperature. Halogen bulbs usually have a much smaller surface area than the equivalent normal incandescent bulb so that area must be at a higher temperature to radiate the same amount of energy.
The OP specifically said 46W halogen bulbs that replace a 60W, so the outer envelopes must be the same.
As I mentioned in my reply.

Looks like this.
#7
Old 04-23-2015, 07:25 PM
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Originally Posted by Huvudtvätt View Post
My halogen bulbs look exactly like traditional bulbs so I guess I should be ok. Unless most of the heat goes to the socket.
Most of the heat is radiated away.
#8
Old 04-23-2015, 09:32 PM
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Why not use LED? Philips has a sale starting next month - two for $5.
#9
Old 04-24-2015, 05:41 AM
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Originally Posted by rsa View Post
Why not use LED? Philips has a sale starting next month - two for $5.
Two reasons:

My light switch is a dimmer so it needs to be dimmable.

The lamp is designed to give off a nice pattern on the walls and ceiling when used with a clear bulb. The light from a LED would be too blurry.
#10
Old 04-24-2015, 09:35 AM
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Halogen bulb envelopes get MUCH hotter than "standard" bulbs. It's part of the process that returns the tungsten to the filament instead of it boiling off via thermionic emisision and plating out on the (relatively cool) bulb envelope. The tungsten ions interact with the halogen gas inside the bulb envelope and slows this down. Unfortunately, it also gets the overall bulbn much hotter than it would get if the halogen gas weren't in there. Halogen bulbs have to run hot in order for bthis all to work.

see here, for instance:

Quote:
In ordinary incandescent lamps, evaporated tungsten mostly deposits onto the inner surface of the bulb, causing the bulb to blacken and the filament to grow increasingly weak until it eventually breaks. The halogen, however, sets up a reversible chemical reaction cycle with this evaporated tungsten. The halogen cycle keeps the bulb clean and causes the light output to remain almost constant throughout the bulb's life. At moderate temperatures the halogen reacts with the evaporating tungsten, the halide formed being moved around in the inert gas filling. At some point, however, it will reach higher temperature regions within the bulb where it then dissociates, releasing tungsten back onto the filament and freeing the halogen to repeat the process. The overall bulb envelope temperature must be significantly higher than in conventional incandescent lamps for this reaction to succeed, however.

The bulb must be made of fused silica (quartz) or a high-melting-point glass (such as aluminosilicate glass). Since quartz is very strong, the gas pressure can be higher,[5] which reduces the rate of evaporation of the filament, permitting it to run a higher temperature (and so luminous efficacy) for the same average life. The tungsten released in hotter regions does not generally redeposit where it came from, so the hotter parts of the filament eventually thin out and fail.
http://en.wikipedia.org/wiki/Halogen_lamp


This is why the envelopes of halogen bulbs are made of quartz, not ordinary glass. It's also why you're not supposed to handle the bulbs directly -- finger oils will etch the glass as it gets hot. Ordinary incandescent bulb envelopes will get hot, but not as hot as halogen bulbs.


This is why they warn about fires. It you put a sheer red cloth across a torchiere lamp for atmosphere you probably won't have any danger from an ordinary incandescent. But a halogen bulb in that torchiere will get hot enough to potentially set that cloth on fire.

Quote:
Halogen torchiere floor lamps are free-standing lamps with a shallow bowl-shaped light fixture mounted on top of a 6-foot pole and illuminated by a tubular halogen bulb. These lamps first became available in the United States in 1983 and sales have grown significantly in the 1990s. The tubular halogen bulbs operate at temperatures much hotter than regular bulbs, and can pose a fire risk if curtains, clothing, or other flammable materials contact the bulb.
http://cpsc.gov/en/Recalls/1997/...e-Floor-Lamps/
#11
Old 04-24-2015, 09:44 AM
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Check out filament led bulbs.

https://earthled.com/blogs/light...tage-led-bulbs
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#12
Old 04-24-2015, 09:46 AM
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Quote:
Originally Posted by Huvudtvätt View Post
Two reasons:

My light switch is a dimmer so it needs to be dimmable.

The lamp is designed to give off a nice pattern on the walls and ceiling when used with a clear bulb. The light from a LED would be too blurry.
They do make dimmable LED lights-- we have several in dimmable light fixtures in our house and they work fine. They are a bit more expensive though-- I recently bought several on sale for about $4 a piece on Amazon.

As for being more blurry than incandescent or halogen light, I don't get that. I don't think those lights are any more 'focused' than LED. I really like the light quality of LED lights- to me it's 1000% better than those curly fluorescent lights.
#13
Old 04-24-2015, 10:26 AM
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to help enlighten things:

every bulb has a transparent or translucent envelope.

a halogen bulb has a quartz envelope which gets very hot. it can start nearby combustible materials on fire. you can damage it if you get combustible gunk (including finger oils) on the bulb.

this quartz envelope halogen bulb may be enclosed in a larger glass bulb which doesn't get as hot and can be touched with bare skin.

the quartz envelopes are smaller, this is what allows them to work. they are long tubular pencil diameter or automobile sized bulbs (think single peanut in a shell).
#14
Old 04-24-2015, 10:31 AM
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Quote:
Originally Posted by CalMeacham View Post
This is why the envelopes of halogen bulbs are made of quartz, not ordinary glass. It's also why you're not supposed to handle the bulbs directly -- finger oils will etch the glass as it gets hot. Ordinary incandescent bulb envelopes will get hot, but not as hot as halogen bulbs.
The OP's talking about the screw-in halogen replacements for incandescent bulbs. They're basically a standard halogen bulb (quartz) within a glass outer bulb that's just like a 60 watt bulb in shape and size. So you can't really touch the actual bulb on those. Similar to the way that a CFL floodlight has the twisted part within a glass reflector and cover.

Apparently a 46 watt halogen puts out roughly the same amount of light as a 60 watt incandescent, so the question really comes out to whether a 46 watt halogen puts out as much heat AT THE OUTER SHELL as a 60 watt bulb?

I think, but don't have any proof, that they're roughly equivalent.

If heat's the real issue, look into LED bulbs; they're instant-on and they put out very little heat relative to halogen or incandescent bulbs.
#15
Old 04-27-2015, 10:37 AM
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Thanks everyone. I must say that I'm still a little confused but I am going to trust beowulff and bump here and assume everything will be fine. As the bulb is exactly the same size and shape as a traditional bulb but only uses 46W, and a traditional bulb gives off 95% as heat (acoording to wikipedia) it makes sense that it shouldn't get much hotter.

Quote:
As for being more blurry than incandescent or halogen light, I don't get that. I don't think those lights are any more 'focused' than LED. I really like the light quality of LED lights- to me it's 1000% better than those curly fluorescent lights.
Most LEDs are encased in a frosted glass envelope or at least have an array of multiple diodes as light sources. That means that light will be dispersed from a much bigger area than it would be from a single filament in a clear bulb. If the light emanates from a single point, the shadows will be sharper, which is what I am looking for.
#16
Old 04-27-2015, 11:04 AM
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Have you considered using a standard 60W appliance clear bulb? (those are still around aren't they?)
#17
Old 04-27-2015, 11:40 AM
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Quote:
Originally Posted by GaryM View Post
I'd suggest that or Edison bulbs, but they usually have multiple filaments.
#18
Old 04-27-2015, 08:30 PM
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Quote:
Originally Posted by bump View Post
Apparently a 46 watt halogen puts out roughly the same amount of light as a 60 watt incandescent, so the question really comes out to whether a 46 watt halogen puts out as much heat AT THE OUTER SHELL as a 60 watt bulb?

I think, but don't have any proof, that they're roughly equivalent.

No well the amount of LIGHT is meant to be the same, thats why they say "hey, this is 46 Watts, so you save an amazing 25% POWER ".

Now the light efficiency is quite low still, so that 46 Watts is making 3 Watts of light.
The rest is heat.

So 43 Watts, of bread cooking water boiling heat, into a glass shell vs 57 Watts into the same glass shell ? It gets more complicated if there is substantial difference in the infra-red but I think its about the same.

So the 43 Watt one has to be cooler.
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