"Baron" <baron.nospam@[EMAIL PROTECTED]
> wrote in message
news:g4lfhd$75u$1@[EMAIL PROTECTED]
> 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.
The lampholder is ok. Oddly enough, I renewed the cable to the lamp a few
weeks ago, as it had gone intermittent at one of the bend loops, and as
the
holder was original, and looking a little worse for wear, I put in a new
one, and a new pressel switch as well, which had failed and been bypassed
long ago ... :-)
Arfa
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