light bulbs and dust

[Hazel]

Here is a simple but good science question - I think. A friend and I are having a friendly debate. Can an accumulation of dust cause light bulbs to explode? Especially if the dust has accumulated directly on the bulb? What about at wall outlets where electric cords are plugged in?

Thank you all for your knowledge.

[excaza]

Personally, I would think not, but I can't back that up.

Halogen bulbs can explode if the surface is contaminated with oils (fingerprints, generally), but I've never heard of an incandescent light bulb exploding from dust.

[Marcus]

Here is a simple but good science question - I think. A friend and I are having a friendly debate. Can an accumulation of dust cause light bulbs to explode? Especially if the dust has accumulated directly on the bulb? What about at wall outlets where electric cords are plugged in?

Thank you all for your knowledge.
I can tell you from long experience that incandescent and florescent bulbs can be coated with sanding dust, fine, airborne dust from wood that is as fine as regular dust, to the point that not much light gets out, but they never explode. Halogen bulbs will burn out with a faint pop, but do not explode or even break open. If enough dust gets inside an outlet, it can impede electrical contact, but that is all.

[DC]

I can tell you from long experience that incandescent and florescent bulbs can be coated with sanding dust, fine, airborne dust from wood that is as fine as regular dust, to the point that not much light gets out, but they never explode. Halogen bulbs will burn out with a faint pop, but do not explode or even break open. If enough dust gets inside an outlet, it can impede electrical contact, but that is all.

when it gets inside it could create a small dust explosion if ignited, or not? a small one :)

[Hazel]

Thank you, Marcus. I am amazed but I know, now that you mention it, that such would be true. I've seen the work tables that I suspect you are talking about. Do you do wood carving?

Thank you also, Excaza. Somehow it just seems to me that heavy dust buildup would cause a burst of the bulb. But, now that I follow Marcus, I can see why not.

[Marcus]

when it gets inside it could create a small dust explosion if ignited, or not? a small one :)
A very tiny one.:)
I do worry a bit about my gas water heater, which is feet from the dusty portion of my shop, but fortunately it is in a closet. Like grain dust, sanding dust at exactly the right level can be explosive, my ventilation system prevents it from getting to those levels though.

Thank you, Marcus. I am amazed but I know, now that you mention it, that such would be true. I've seen the work tables that I suspect you are talking about. Do you do wood carving?
I specialize in inlay rather than carving, like the jewelry box pictured in my avatar.


Thank you also, Excaza. Somehow it just seems to me that heavy dust buildup would cause a burst of the bulb. But, now that I follow Marcus, I can see why not.

[Hazel]

Thank you. I have seen some beautiful inlay work. "Slow, patient, easy does it" work and it comes out classic art. I'd never be able to do it. Harks back to the old mosaics but, to my belief, wood is better.

Have a good day. Hazel

[OnlyTellsTruths]

What about at wall outlets where electric cords are plugged in?


The rest of the questions have been covered, but I'm pretty sure this 3rd one does happen.

If enough dust (probably has to include pet hair, human hair) gathers at the socket and bridges the gap between the 2 prongs it will catch fire. The plug has to be not completely plugged in of course, so that a tiny bit of the prongs are exposed. Also, it probably 'helps' if the device plugged in pulls a lot of juice, such as a space heater.

[shadron]

The rest of the questions have been covered, but I'm pretty sure this 3rd one does happen.

If enough dust (probably has to include pet hair, human hair) gathers at the socket and bridges the gap between the 2 prongs it will catch fire. The plug has to be not completely plugged in of course, so that a tiny bit of the prongs are exposed. Also, it probably 'helps' if the device plugged in pulls a lot of juice, such as a space heater.

No, the current that the device pulls is irrelevant, as you're essentially shorting the device out with the dust. And no, it won't always be able to conduct enough electricity to cause a fire, though you can't obviously count on that. What will affect it's ability to catch fire is the thickness (gauge) of the wiring feeding the socket and how well the wiring is protected by the circuit breaker or fuse in the breaker box, as well as the nature of the material, the voltage present in the plug, and the humidity.

[trvlr2]

Incandescent bulbs can get hot enough to ignite heavy accumulations of flammable dust. Halogens, too.(Partly the reason hlogen bulbs have a glass outer cover-protects the bulb from environment, and vice versa.)
I have never heard of them exploding, which means nothing. I would think it improbable, as they would implode rather than explode.
I have indeed, started a fire with an incandescent 60 watt bulb. I hope to not do that again. (Flammable material actually really close, or touching the bulb.)
E-Z Bake oven, anyone? Not mine. Really.

[Marcus]

The rest of the questions have been covered, but I'm pretty sure this 3rd one does happen.

If enough dust (probably has to include pet hair, human hair) gathers at the socket and bridges the gap between the 2 prongs it will catch fire. The plug has to be not completely plugged in of course, so that a tiny bit of the prongs are exposed. Also, it probably 'helps' if the device plugged in pulls a lot of juice, such as a space heater.
With respect to sanding dust and sawdust, there is good news and bad news: it's a poor conductor of electricity, but if there were to be a spark a fire could result. When I occasionally blow out all the sawdust from the insides of the outlet boxes and circuit boxes I check all the connections, a loose wire could be disastrous.

On a related topic, not that anyone asked for it, I have also conducted experiments by throwing handfuls of sawdust on the bare elements of space heaters to see if a fire would result. The result is no fire, it seems that the flamable material has to remain in contact with the bare red hot elements for some short period of time.

[arthwollipot]

I am given to wonder - what is the mechanism by which such an explosion might happen? An incandescent light bulb isn't under pressure, as far as I know - the only pressure which might cause an explosion (rather than simple cracking or breaking) would be the expansion of gases contained in the bulb under heat. But I'm pretty sure this mix of gases is specifically designed not to expand enough to explode the glass under normal use. But we have to consider the effect of dust on the surface of the bulb. Can heating dust cause irregularities in the glass of the bulb? Create hot spots that are more susceptible to breakage than other parts of the bulb? I don't know, but these are the things you need to think about when you consider whether dust can cause a bulb to explode.

[JoeTheJuggler]

Here is a simple but good science question - I think. A friend and I are having a friendly debate. Can an accumulation of dust cause light bulbs to explode? Especially if the dust has accumulated directly on the bulb?

When I was 5, I thought a lit basement lightbulb (traditional incandescent--this was the mid-'60s) made a great squirt gun target, and I was surprised when it exploded!

I wonder if dust on the surface of an incandescent bulb can attract condensation causing the same thing? I suspect not, because condensation wouldn't result in quick cooling of the bulb. In fact, you'd only get condensation when the bulb is cool (off), and as it heats up, I imagine any moisture already there would evaporate and no new condensation would happen.

[ApolloGnomon]

Any shattered glass would be caused by uneven heating and/or cooling. That's why halogens can be destroyed by a fingerprint. Theatre lamps (lightbulbs for the non-stagehands in thread) are notorious for this. The film of oil from a fingerprint collects enough of the heat output to create a localized hot spot on the envelope. Ordinary household incands don't get hot enough for this to matter. But squirting water on 'em, that'll do it every time.

Sorry, I've never sees dust in any quantity causing any electrical or physical failure with either Edison-base bulbs or with electrical outlets.

[DavidS]

when it gets inside it could create a small dust explosion if ignited, or not? a small one :)
Any incandescent bulb compromised enough to let dust get inside already has bigger problems than the dust. The whole point of the bulb part is to keep out unwanted gas molecules (e.g. oxygen) that would trash the hot filament.

Unless the bulb was built with the dust inside, of course.

[ApolloGnomon]

There was a moment in a movie (sorry, don't remember which one) where someone was assassinated by a lightbulb with something flammable like lighter fluid introduced into the envelope. When the victim turned on the overhead light the bulb shattered and showered him with flaming glass shards.

I think it was a prison movie. Don't know if it would really work, I've never been brave/stupid enough to try it out for myself.

[ImaginalDisc]

There was a moment in a movie (sorry, don't remember which one) where someone was assassinated by a lightbulb with something flammable like lighter fluid introduced into the envelope. When the victim turned on the overhead light the bulb shattered and showered him with flaming glass shards.

I think it was a prison movie. Don't know if it would really work, I've never been brave/stupid enough to try it out for myself.

The Longest Yard. :-p

[Dr.Sid]

There was a moment in a movie (sorry, don't remember which one) where someone was assassinated by a lightbulb with something flammable like lighter fluid introduced into the envelope. When the victim turned on the overhead light the bulb shattered and showered him with flaming glass shards.

I think it was a prison movie. Don't know if it would really work, I've never been brave/stupid enough to try it out for myself.

Oh ! I was brave/stupid enough ! It totally did not work. When the filament is sunk in the gasoline (that's what we used), it just wont do anything. It just warms the gasoline. But even if there is little gasoline, so the filament is free .. it does not glow hot enough. The vapors and air inside are enough to cool the filament, and 60W lightbulb filament just barely got glowing. It seems like the filament needs vacuum inside to minimize the heat transfer to really glow.
I used smaller lightbulbs (4.5V ones, for flashlight) to successfully light a firecracker .. but it too clearly suffered from the fact the the vacuum was removed and it glowed a lot less then before I removed the glass. But the firecracker explosive is much easier to light then gasoline.

As for exploding lightbulbs due the dust .. I for sure had exploding lightbulb which seemed to be just dusted. True it was a lot of dust, and it was 500W lightbulb, so there was lots of head involved.

[Hazel]

Oh ! I was brave/stupid enough ! It totally did not work. When the filament is sunk in the gasoline (that's what we used), it just wont do anything. It just warms the gasoline. But even if there is little gasoline, so the filament is free .. it does not glow hot enough. The vapors and air inside are enough to cool the filament, and 60W lightbulb filament just barely got glowing. It seems like the filament needs vacuum inside to minimize the heat transfer to really glow.
I used smaller lightbulbs (4.5V ones, for flashlight) to successfully light a firecracker .. but it too clearly suffered from the fact the the vacuum was removed and it glowed a lot less then before I removed the glass. But the firecracker explosive is much easier to light then gasoline.

As for exploding lightbulbs due the dust .. I for sure had exploding lightbulb which seemed to be just dusted. True it was a lot of dust, and it was 500W lightbulb, so there was lots of head involved.

If you like a bit of light reading, you might enjoy a book I just finished. "Hot Money" by Dick Francis. I won't say about the story line itself, whether it is something you'd like, but the demonstrations about how someone blew up a house with fertilizer and some detonators and a child's home-made toy timer was quite interesting.

[Dr.Sid]

If you like a bit of light reading, you might enjoy a book I just finished. "Hot Money" by Dick Francis. I won't say about the story line itself, whether it is something you'd like, but the demonstrations about how someone blew up a house with fertilizer and some detonators and a child's home-made toy timer was quite interesting.

Uh .. I better not read anything like that. I let my skills sleep till some war with robots or something .. :)

[ApolloGnomon]

The Longest Yard. :-p

Oh yeah, that thing. The light bulb thing was the most memorable bit of the movie for me.

[ApolloGnomon]

Oh ! I was brave/stupid enough ! It totally did not work. When the filament is sunk in the gasoline (that's what we used), it just wont do anything. It just warms the gasoline. But even if there is little gasoline, so the filament is free .. it does not glow hot enough. The vapors and air inside are enough to cool the filament, and 60W lightbulb filament just barely got glowing. It seems like the filament needs vacuum inside to minimize the heat transfer to really glow.
I used smaller lightbulbs (4.5V ones, for flashlight) to successfully light a firecracker .. but it too clearly suffered from the fact the the vacuum was removed and it glowed a lot less then before I removed the glass. But the firecracker explosive is much easier to light then gasoline.

As for exploding lightbulbs due the dust .. I for sure had exploding lightbulb which seemed to be just dusted. True it was a lot of dust, and it was 500W lightbulb, so there was lots of head involved.

So you were filming pron in a dusty attic? Links? ;)

I make pyro ignitors with ordinary "twinkie light" bulbs, like these:
http://www.youtube.com/watch?v=xS8rztYgDzk

The lamps themselves run fine if a bit bright at 12vdc, but when connected in series for a string of xmas lights they run on 110. With the tip broken off an the glass filled with black powder they make a nice ignitor. Some high power rocketry folks use 'em for altitude-controlled parachute deployment. With a minimal amount of attention to detail they're pretty reliable. I fire them off with my 12v rocket launch box.

[BowlOfRed]

Oh ! I was brave/stupid enough ! It totally did not work. When the filament is sunk in the gasoline (that's what we used), it just wont do anything. It just warms the gasoline. But even if there is little gasoline, so the filament is free .. it does not glow hot enough.

My college roommate did lots of experiments stuff like that (*before* arriving at college). He filled the bulb with homemade gunpowder. That worked. Back when you could go down to the pharmacy and buy dangerous materials by the tub.

"Randy! What are you doing down in the basement?"
"Nothing, Ma!"

[dlorde]

Oh ! I was brave/stupid enough ! It totally did not work. When the filament is sunk in the gasoline (that's what we used), it just wont do anything. It just warms the gasoline. But even if there is little gasoline, so the filament is free .. it does not glow hot enough. The vapors and air inside are enough to cool the filament, and 60W lightbulb filament just barely got glowing. It seems like the filament needs vacuum inside to minimize the heat transfer to really glow.
I used smaller lightbulbs (4.5V ones, for flashlight) to successfully light a firecracker .. but it too clearly suffered from the fact the the vacuum was removed and it glowed a lot less then before I removed the glass. But the firecracker explosive is much easier to light then gasoline.

With gasoline, you need a suitable vapour concentration - made me wonder whether much less gasoline would be better, e.g. a little in the bottom of the bulb, so that a small amount of explosive vapour has time to form before the filament burns out... heh heh!

[Dr.Sid]

With gasoline, you need a suitable vapour concentration - made me wonder whether much less gasoline would be better, e.g. a little in the bottom of the bulb, so that a small amount of explosive vapour has time to form before the filament burns out... heh heh!

Problem is the filament WONT burn out. When there is gas inside, it will just barely glow. It will be much colder then usual.

[ApolloGnomon]

The trick with the xmas lite pyro is that 12vdc is actually too much for the filament, so they burn hot enough.

maybe one could use a 110v light bulb in a 220v system and the filament would get hot enough to ignite a stoichiometric mixture.... if not, we'll just fill the light bulb with TNT.

[rjh01]

The trick with the xmas lite pyro is that 12vdc is actually too much for the filament, so they burn hot enough.

maybe one could use a 110v light bulb in a 220v system and the filament would get hot enough to ignite a stoichiometric mixture.... if not, we'll just fill the light bulb with TNT.

Not TNT, C4.

[freedy]

Before you can answer that question, you must understand how a light bulb works.

A light bulb does not give off light, but rather absorbs dark.
The more powerful the bulb the more dark it absorbs. So as dust gathers on the surface of the bulb it absorbs less and less dark until no dark can get in and the dark stays in the room.
With no dark building up inside the bulb, it is unlikely to explode.

I know light bulbs absorb dark, because when they fail you can see a thin layer of dark on the glass.

[BillC]

When I was 5, I thought a lit basement lightbulb (traditional incandescent--this was the mid-'60s) made a great squirt gun target, and I was surprised when it exploded!

I'm similarly guilty.

[fishbait]

I experiment with hi-speed ballistic photography.
A thread about lightbulbs gives me the opportunity to gratuitously post some of my images of a lit bulb being blasted with a gun.

http://img.photobucket.com/albums/v282/fishbait/DSC_0011.jpg?t=1280939611

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http://img.photobucket.com/albums/v282/fishbait/DSC_0013-2.jpg?t=1280939401

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http://img.photobucket.com/albums/v282/fishbait/lb.jpg?t=1280937991

[ApolloGnomon]

Keen! I've snagged them for desktop pix!

[JoeTheJuggler]

I experiment with hi-speed ballistic photography.
A thread about lightbulbs gives me the opportunity to gratuitously post some of my images of a lit bulb being blasted with a gun.

Very nice. Can you do the same thing but trying to catch the explosion of a hot bulb from being squirted with water?

[fishbait]

ApolloGnomon: Keen! I've snagged them for desktop pix!Thanks, AG! It's great to have my efforts appreciated. If you like these, I have some shots that will knock your socks off!


These are rather crude compared to the really good shots!
I have hundreds of ballistic shots and blasting all sorts of stuff. Water balloons, eggs, fruit, yogurt, ...all kinds of cool stuff being blown apart!

I don't went to derail this thread, but if anyone is interested, I could start a thread with some really cool ballistic shots.

[fishbait]

Very nice. Can you do the same thing but trying to catch the explosion of a hot bulb from being squirted with water?I hadn't thought of that. I will give it a go when I set up the blasting studio.

I do a lot of ballistic shots of stuff frozen in liquid nitrogen (-321F). I'll do an experiment where the hot, lit bulb is doused with a liter of N2. Should be rather interesting, I think!

Here's a clear, lit bulb whacked with a hammer.

http://img.photobucket.com/albums/v282/fishbait/LITBULB.jpg?t=1282509010