by ericmark »
Sat Dec 20, 2008 11:01 pm
You say housing circuit tripped so I would assume that is in consumer unit? Normally a 6 amp B type would be used so up to 30 amp may have flowed before it tripped. Many fans have manufactures instructions to use 3 amp fuse without this protection it may have blown a printed circuit track if cheap bulbs without internal fuses are used.
When a bulb blows it can caused ionisation which means the gas inside the bulb becomes conductive. Good quality bulbs have built in fuses which will blow if this happens. When this does happen the glass often goes a black/blue colour and the bulb seems to flash as it blows. Without the built in fuse to current can go very high a MCB will normally trip in under 40ms but a B6 MCB will take between 18 to 30 amp to trigger the magnetic part of the trip even higher in first 40 ms which is why electronic equipment is often protected by a fuse rather than a trip as with a short circuit a fuse will often rupture quicker than a trip can open.
I hope I am wrong and this has not happened in your case. But with no details on fitting or exactly what opened due to fault only a general answer can be given. Although even if you did give more manufactures do not tend to give out details on how the fan is made so likely could not be more specific even if more was known.
Eric
