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
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
Have others here had such experience?
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.
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 :)
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.
From the Sofa of Brian Gaff Reply address is active
"Nick" < snipped-for-privacy@NOSPAM.tiscali.co.uk> wrote in message
On Tue, 7 Jul 2015 23:50:37 +0100, "Nick"
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.
Had a couple of 50W GU10s shatter in similar fashion last year, can't
remember the make except that they were not "pound shop specials".
Only incandescent we have left now is in the outside light by the front
door, when that finally fails it will be replaced by LED :)
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
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
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