Halogen lamp explosive disassembly

28.09.2009 18:06

Ever wonder what is the reason behind that big fat warning that you shouldn't use your halogen desk lamp without the protective glass? After yesterday evening I know why.

The 20 W 12 V halogen light bulb on my desk went out with a loud bang, disintegrating into tiny little pieces. They were mostly caught by the glass shield. Those that escaped at the edges were the size of fine glass dust and covered my desk, giving it a fancy shiny look.

This is how things looked when I removed the safety glass today:

Remains of an exploded 20 W halogen lamp

There's a white residue on the safety glass that appears to come from the bulb pieces. I'm still wondering where that came from.

Dents in the reflector caused by lamp explosion

It's a little hard to see here, but the aluminum reflector is full of little dents. So counting in the apparent force of the explosion and the high temperature of the bulb, that glass shield most probably saved me a couple of burns on my hands.

The box of the new bulb I bought (made by Philips by the way) says it can be used in fittings without cover glass. Somehow I tend to disagree with that.

Update: here's a better photograph of the white residue on the safety glass.

White residue on the safety glass

Posted by Tomaž | Categories: Life


We use a lot of halogens, (unfortunately) at work, though they're all 50MR16/EXN/C's with integrated reflectors and thus are self-encapulated; and I've yet to see any unexpected rapid disassemblies from them.

What do like to self destruct are the CF26DD/835s in a couple highbay installations. Since they're the 2-pin, non ECO versions of the CF26DD, they don't have thermal fusing, and are perfectly happy to fuse themselves to the socket when they burn out.

>There's a white residue on the safety glass that appears to come from the bulb pieces.
>I'm still wondering where that came from.

Residue on the safety glass on picture seems to be in bright-metal color - not white - so I would say that it's tungsten. The white powder is glass - as you probably know.

Posted by Igor

It's opaque white, not reflective like a metal coating - see the close-up photo I added to the post above.

I doubt it's only glass powder. It stuck to the surface and only came off after I rubbed the glass under water.

Also you can see how only the pieces of the bulb seem to be surrounded by it. As if something evaporated from them and then condensed on the cooler safety glass.

Posted by Tomaž

Can you reproduce this?

Posted by Luka Rahne (via Facebook)

Not really. And if I could I don't think I would want to.

Posted by Tomaž (via Facebook)

Looks like assasination atempt to me...

Posted by Gašper Korinšek (via Facebook)

White residue is probably tungsten oxide, chemical compund from burning in air, not tungsten itself.

Posted by ResR

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