Arfa Daily Inscribed thus:
> 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.
Don't count on the lampholder being undamaged ! The springs in the
holder that apply pressure to the contact pads on the bulb, weaken with
both age and heat. It would be wise to replace the lamp holder.
> 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 ?
Yes the smaller glass envelope does increase the heat considerably !
The bulb produces a little more light as well. I don't know that being
lead free makes a lot of difference, the heat sure does though !
> 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
Yes I agree, overheating is a problem. I enlarged the vent holes on my
desk lamp for that reason. I used a nibbling tool that I bought at
Radio Shack when I was in the USA a few years ago.
--
Best Reagrds:
Baron.
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