On 21 Apr, 12:59, (Andrew Gabriel) wrote:
In article ,
* * * * Peter Scott writes:

Lee wrote:
I've just had a (mains) GU10 shatter into nice sharp shards all over the
floor, rather impressive spread given the small amout of glass involved...

I was under the impression that these bulbs weren't meant to do this....
Should I be worried any others might follow suite? (These are branded,
not no-names) Just concerned for ours and the cats feet

Lee
You didn't buy them from Poundland did you? I bought some filament bulbs
from it a while back and they exploded after a while. Trouble was I
couldn't remember which was which, so it was just a question of waiting..
Interesting time (in the Chinese sense).

That can happen when the bulb has no integral fuse, which means
it can flash-over as an unbalasted discharge lamp when the
filament breaks, with the current being limited by the supply
impedance, and the rapid expansion of the gas fill causing it
to explode.

Ordinary mains bulbs are required to be internally fused.
In some other countries, this isn't mandated, and occasionally
stock gets here without internal fusing, but it's rare.

Halogens are a different matter. Many halogen lamps simply have
nowhere to include a fuse within the bulb. These are handled by
having a secondary shield, either an outer glass bulb which
should contain the quartz shattering, or a fitting with similar
a shield. Halogens run at a higher pressure inside anyway, and
this reduces the chance of flash-over. However, if it does
happen, it generates a higher pressure in the quartz bulb.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

My input would be to switch over from the 240v driven GU10's to the
equivalent using a 12v transformer. All GU10's I ever used had a very
high failure rate - the 12v one's never give me any bother, which is
suspect is due to the some sort of surge suppression when they are
switched on.
Rob