For twenty odd years, I have had the same Terry's Anglepoise bench lamp in
service. I have always used perfectly normal 60 watt incandescent lamps in
it, without any problem at all. Although the metal shade used to get quite
warm, it was never enough to actually burn you when your forehead
accidentally connected with it.
Recently, the light bulbs I've been seeing and buying, seem to have
reduced
in size from the old 'tennis ball' size, to something closer to a snooker
or
pool ball (but not as small as the established 'golf ball' types often
used
in multibranch ceiling lights and light / fan fittings.)
I have noticed that these new smaller bulbs run a whole quantum leap
hotter
than the older larger size, and they hot up the shade on the bench light
until it is unbearably hot to touch. Today, I left the workshop for a
while,
and when I came back, the air was full of that 'fishy' sort of smell you
get
when something like a wall socket or the plug that's in it, is burning. A
hunt around for the source, brought me to the bench lamp, which was still
alight. When I moved it, it went off. When it had cooled down a bit, I
took
the bulb out (a UK bi-pad bayonet cap rather than a U.S. edison screw
type)
and I was horrified to see that one of the solder pads had just about
burnt
away completely, and the black insulation material in the base had started
to burn as well. Fortunately, the brass lampholder was undamaged.
So, has anyone else noticed how hot these smaller bulbs run ? Are we
talking
dangerous here if they are used in any fitting where they hang downwards ?
Any suggestions as to why there is such a large increase in temperature ?
Yes, I can see that the glass envelope is closer to the filament, and that
it has somewhat less surface area to radiate the heat away from, but I'm
not
sure that either of those are enough to account for just how much hotter
they seem to run. And why had one pad burnt away?Anything to do with the
solder being lead-free and less malleable than before, reducing the spring
loaded contact area maybe ?
A bit worrying as I'm sure that there will be many situations where a
fitting that has previously been quite happy with a 60 watt bulb in it,
will
now overheat, with possibly catastrophic consequences ...
Arfa
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