"mogga" wrote in message
...
On Sat, 01 Oct 2005 11:11:39 +0100, Dave Fawthrop
wrote:

On Sat, 01 Oct 2005 09:53:26 GMT, "Dave P"
wrote:

| I found my bedroom light bulb had failed yesterday - it's a standard
bayonet
| fitting below a ceiling rose. However, it wasn't as simple as just
changing
| the lightbulb - the bulb had fallen out of the fitting. Inspection of
the
| socket showed that it had largely melted, in fact one of the two metal
| spring-loaded electrical connection pins had dropped out, covered with
burnt
| plastic and melted lead from the bulb contact. The bulb had fallen out
| because one of the socket cut-outs, which retain the lugs on the bulb,
had
| just disintegrated or melted with the heat.

A bad contact generated enough heat to melt things, but did not draw
enough
electricity to trip anything.
|
| It sounds like I was lucky not to have a house fire, wasn't I (or not?)?
| Why would this happen? Why didn't the relevant MCB on my CU trip (they
seem
| to do so - irritatingly - every time a bulb in the house blows!) The
fitting
| was only about 4 years old, is wired perfectly OK, and it's months since
| I''ve changed the lightbulb which has worked perfectly ever since. I
find
| it pretty scary to think what migh have happened, and I haven't a clue
why.

I have changed to energy saving ?bulbs?, long ago, so changing them is a
very rare occurrence. Also because they use less power they do not run
anything like as hot. I have a bad contact in my bedside light, which I
must change sometime, but as it only uses 7 watts it is never going to
burn
out.

I've had an energy saving light melt - or at least the plasticy bit
did. About a week afterI'd thrown the wrapper out after having had it
a couple of years.
I've had a filament light bulb drop out of its socket before.
There was a flash and a thump, and I saw on the landing the baseless glass
bulb lying on the carpet. Getting the base out of the pendant socket was
interesting. The plastic pendant socket was unharmed though.

When a filament lamp blows, you can get arcing inside
as hot tungsten splatters about, and the
current can be enough to blow a fuse. If it isn't quite
enough, I suspect that if the contact of the base of the bulb to the socket
isn't very good, the solder can melt and allow the bulb to drop out.

Andy.