2 days ago I fitted a halogen GLS 42W ES lamp to a hall light. Only used in the evenings, so this time of year not very much at all. Turned it on this evening and sat down for a bite and a little of the crap on television. Short while later a loud bang from the hallway and no light. Hallway showered with tiny shards of glass. Lamp had exploded. I have never experienced such before but it is potentially dangerous not only to me and my wife but also to our children and grandchildren when they visit. Also dangerous to the pets that we live with. FWIW the lamp is from Knightsbridge (the mark of quality) Halo Saver Lamp model :Halo-G42ES.
Have others here had such experience? Thanks, Nick.
Fingerprints on the quartz will cause that. There's usually a warning on the package to that effect.
Organic contaminants, such as oil, are often blamed but in reality vaporize very quickly so probably aren't the real problem. Salts and other metal-containing materials are more likely to be the real issue. Sodium and other alkali metals will diffuse into the quartz at high temperature and dramatically increase the local thermal expansion coefficient. This stresses the bulb.
So wear clean cotton gloves or handle the bulb only with a clean cloth. If you accidentally touch the bulb, wipe it with isopropyl alcohol a couple of times.
I only ever had one Halogen, a mains voltage one in the kitchen. Obviously I now do not need light, but it was removed because it exploded more than once. Some sort of protection was definitely needed here! Are the low voltage transformer driven ones any less volatile? The light to me was always a bit kind of yellow and hard. Brian
I assume you are talking about the type of bulb which comprises a halogen capsule inside a conventional form factor glass bulb which looks like an old incandescent bulb?
If so, yes I've had the same except that in my case the outer bulb exploded leaving the halogen capsule still illuminated. That created two risks, that from the glass fragments and also from the very high temperature of the exposed halogen capsule.
Can be even more dramatic with discharge lamps, used to see many that had what could only be described as "blisters" on the glass in the same places they had been handled. Didn't stop people touching the replacements though :)
TV studio halogens can do the same - occasionally on a live broadcast. Could probably find one on U-Tube. But they have a lens in front of the bubble to contain the glass shards.
Don't remember ever seeing a soft light blow up. Seemed to be restricted to hard sources. Or at least far more common. Maybe to do with the type of bubble used.
Seen it once with a GLS (non-halogen). It was a table lamp, and exploded in the middle of dinner, entertaining the guests (I was one of the guests).
What happens is the filament breaks, and you get a tiny spark between the ends as they come apart. Very occasionally, this grows into a bigger arc. It has a much lower impedance than the filament, so the ends of the arc walk away from the break in opposite directions, shorting out more and more of the filament until they reach the lead-in wires, at which point you have a low impedance arc sorting out the lamp. This happens in a fraction of a second, and normally causes a bright flash and a pop.
In a GLS lamp, the two lead-in wires are fused by being thinned as they pass down into the lamp base, and normally these two fuses both blow. If the circuit is on an MCB, that will often trip too. These prevent enough current flowing to cause the gas fill to heat up and expand sufficiently to cause the bulb to explode. In your case, this protection failed for some reason. Some lamps (such as GU10's) have no space for an integral fuse, but they are supposed to be able to contain the exploding capsule. Unfused bare halogen capsule lamps either have to be low pressure type (in theory so the heating can't generate enough pressure to explode - only applies to 12V ones), or the fitting has to provide the protection, e.g. in the form of an enclosed housing with glass cover. GLS however are supposed to always have the integral fuses, as the bulb is not strong enough to contain the explosion.
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