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

Arfa Daily wrote in message
...
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



I usually use circular fluourescent lamp of an anglepoise inspection lamp
for bench illumination but sometimes use a traditional one (Luxo for those
over there). In that I have a 60Watt one that is conical in shape, like
Apollo earth lander capsule, that has silvering on the cone so directs both
heat and light forwards unlice dichroic which is designed to pass heat
through to the rear and light forward. The cover gets about as hot as
something less than a 40W standard bulb. They may be used for shop display
purposes these silvered bulbs. As most of the rearwar light is directed
forwards more efficiently than a cluttered white cover then perhaps
equivalent to standard 150W illumination in the direction where you want it

The ones I have are coloured but I scrape the varnish off the front, Endon
Accessories Reflector R080 type

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"N_Cook" wrote in message
...
Arfa Daily wrote in message
...
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



I usually use circular fluourescent lamp of an anglepoise inspection lamp
for bench illumination but sometimes use a traditional one (Luxo for those
over there). In that I have a 60Watt one that is conical in shape, like
Apollo earth lander capsule, that has silvering on the cone so directs
both
heat and light forwards unlice dichroic which is designed to pass heat
through to the rear and light forward. The cover gets about as hot as
something less than a 40W standard bulb. They may be used for shop display
purposes these silvered bulbs. As most of the rearwar light is directed
forwards more efficiently than a cluttered white cover then perhaps
equivalent to standard 150W illumination in the direction where you want
it

The ones I have are coloured but I scrape the varnish off the front, Endon
Accessories Reflector R080 type

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



I'll have a look for some. Without any desire to re-open the CFL thing
again, I currently have one of those in it, as it was all I had to hand. The
light from it is useless in this application ...

Arfa

As far as appearance, like a bayonet version of the leftmost one of these
http://www.global-b2b-network.com/di...ector_Lamp.jpg
Perhaps 80 percent of the rearward cone is silvered, so reflecting that part
forwards, both heat and light.

Anglepoise is one of my favourite made-up words, precisely giving its
mechanical function , unlike Luxo which could be anything involving light.
If the workroom gets too hot I have an 6 inch fan mounted on the anglepoise
arms of an ex-light.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

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.

In article ,
Arfa Daily wrote:
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 ...

I've got a CFL in mine - but not an ordinary one. It's an RO80 substitute
made by GEC and a genuine 100 watt equivalent, but only 20 watts or so.
Decent colour temperature too. Takes a wee while to come up to full output
- but not a problem for this sort of use. The price may be, though. ;-)

--
*Always drink upstream from the herd *

Dave Plowman London SW
To e-mail, change noise into sound.

"Baron" wrote in message
...
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

On Fri, 4 Jul 2008 01:23:49 +0100, "Arfa Daily"
wrote:

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.

As I understand it (possibly wrong), the higher the temperature of the
filament, the more efficient the incandescent light bulb in lumens per
watt. There's a bit of a clue at:
http://en.wikipedia.org/wiki/Incandescent_light_bulb
During ordinary operation, the tungsten of the filament evaporates;
hotter, more-efficient filaments evaporate faster. Because of this,
the lifetime of a filament lamp is a trade-off between efficiency
and longevity. The trade-off is typically set to provide a lifetime
of several hundred to 2000 hours for lamps used for general
illumination. Theatrical, photographic, and projection lamps may
have a useful life of only a few hours, trading life expectancy
for high output in a compact form. Long-life general service lamps
have lower efficiency but are used where the cost of changing the
lamp is high compared to the value of energy used.

In other words, the newer smaller bulbs are trading efficiency for
lifetime, which is the result of running hotter. I'm not sure why the
bulb is smaller. My guess(tm) is that it's simply thicker, which
allows the use of a smaller bulb size, which can withstand the heat
better than a thin bulb and can handle a higher internal gas pressure
(which is necessary to prevent filament evaporation).

More on the subject:
http://en.wikipedia.org/wiki/Luminous_efficacy
http://members.aol.com/ajaynejr/lumen.htm

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Arfa Daily wrote:


"Baron" wrote in message
...
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,

Yes ! The middle one. The original cable was fabric woven sheath over
rubber. I replaced it with "electric iron" cable but that didn't last
as long as the original one. I've now got a modern plastic insulated
cable in there. Its much thinner and more flexible. I used cambric
spaghetti over the wires at the bulb holder end just in case the heat
damaged the plastic insulation.

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

That little push on push off switch went a very long time ago ! There
is just the hole now, adding to the ventilation !

--
Best Regards:
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,

Yes ! The middle one. The original cable was fabric woven sheath over
rubber. I replaced it with "electric iron" cable but that didn't last
as long as the original one. I've now got a modern plastic insulated
cable in there. Its much thinner and more flexible. I used cambric
spaghetti over the wires at the bulb holder end just in case the heat
damaged the plastic insulation.

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

That little push on push off switch went a very long time ago ! There
is just the hole now, adding to the ventilation !

--
Best Regards:
Baron.

I too have a thin plastic cable in there. There was a good reason that I
changed it apart from the intermittency. Over the years, it has had a lot of
'half-arsed' repairs done to it. I'm sure if you have one, you know exactly
what I mean. It's half past two, and the guy is coming to pick up his
amplifier that you have assured him will be ready at half past four, and the
bench light starts going on and off ... Well, a long time ago, some silicon
sheathed heat-resistant wire had gone into the lampholder, and been joined
to the feed cable (via the pressel switch bypass ...!!) with a bit of
plastic choc-bloc. Yes, I know, but I didn't have a ceramic one to hand.

Anyway, it had been fine until I started using these small very hot bulbs in
it, whereupon the nylon insulation on the bloc had crisped up. Well, a
couple of weeks ago, I had one hand on the (earthed) chassis of an amp I was
working on (no, it wasn't plugged into the bench isolation tranny as it
should have been !) and I grabbed the Anglepoise shade to pull it into a
more convenient position. A microsecond later, the air turned blue as a
stream of profanity flowed from my mouth ...

The crisped up insulation on the choc-bloc had left a mains leakage path to
the metal shade. I decided there and then that no such thing was going to
happen again, so I have now rewired it with a thin three-core cable, and
grounded the metalwork to mains earth, via the earth connector on the brass
lampholder. Silicon sleeving has also been fitted to the wire ends in an
effort to proof them at least some, against future heat problems.

I've got to admit that the shock I got from the setup was a bit of a wakeup
call, as it's often the case that your forehead brushes agains the lamp
shade, as you try to stick your head inside some recalcitrant item that's on
the bench for repair. At least now, if there should be any future leakage
issues, it should just whack the RCD out.

Arfa

"Jeff Liebermann" wrote in message
news
On Fri, 4 Jul 2008 01:23:49 +0100, "Arfa Daily"
wrote:

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.

As I understand it (possibly wrong), the higher the temperature of the
filament, the more efficient the incandescent light bulb in lumens per
watt. There's a bit of a clue at:
http://en.wikipedia.org/wiki/Incandescent_light_bulb
During ordinary operation, the tungsten of the filament evaporates;
hotter, more-efficient filaments evaporate faster. Because of this,
the lifetime of a filament lamp is a trade-off between efficiency
and longevity. The trade-off is typically set to provide a lifetime
of several hundred to 2000 hours for lamps used for general
illumination. Theatrical, photographic, and projection lamps may
have a useful life of only a few hours, trading life expectancy
for high output in a compact form. Long-life general service lamps
have lower efficiency but are used where the cost of changing the
lamp is high compared to the value of energy used.

In other words, the newer smaller bulbs are trading efficiency for
lifetime, which is the result of running hotter. I'm not sure why the
bulb is smaller. My guess(tm) is that it's simply thicker, which
allows the use of a smaller bulb size, which can withstand the heat
better than a thin bulb and can handle a higher internal gas pressure
(which is necessary to prevent filament evaporation).

More on the subject:
http://en.wikipedia.org/wiki/Luminous_efficacy
http://members.aol.com/ajaynejr/lumen.htm

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Interesting thoughts. Really not a good thing though, I am thinking. It's
only been a matter of a few months that I have been using these small bulbs,
and they have already caused a problem with a lamp that had previously been
running daily, without heat-related problems, for years. It seems to me that
in certain domestic applications, these could represent a significant fire
hazard. Take for instance, a 'standard' pendant room light fixture,
suspended on normal plastic cable. There is not normally enough heat
generated, to cause a problem with the insulation, but I'm sure that with
the increased temperature that these things run at, there's going to be.

Take also, a typical lampshade made from either plastic or paper based
sheet. These will typically have a sticker in them saying something like "60
watt max lamp". Now that figure is a fire safety one, based on the heat
generated by a typical 60 watt bulb. What about when you put one of these
new ones in ? I would guess that the heat steaming off them, is at least
equivalent to what you would be expecting from a traditional-sized 100 watt
bulb. So even putting in a correctly rated 60 watt bulb, you could be
thermally overloading that shade, by 60 odd % . Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

Arfa

On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp. I have a few here and
they all specify 60 watts maximum. I guess that applies only to the
old large bulbs.

This is probably what's happening:
http://rabi.phys.virginia.edu/HTW/page1.php?QNum=1042
Yeah, looks about right.

Wanna disclose the maker and model number of the hot bulb?

http://rabi.phys.virginia.edu/HTW/incandescent_light_bulbs.html
Candle flame = 1700 C
Match = 2000 C peak
100 watt bulb = 2500 C

Are a few degrees C going to make much of a difference? I don't have
the proper IR thermometer necessary to measure such high temperatures.
See if you can beg or borrow an optical pyrometer used in a steel mill
or foundry, you can measure the temperatures. Forget about using
thermocouples as they don't cover the temperature range:
http://en.wikipedia.org/wiki/Thermocouple

Meanwhile, use an IR optical thermometer to measure the temperature of
the lamp shade, to see if it's ready to ignite. Compare the old and
new bulbs. A few measurements will tell you if you're in danger of
burning the house down. Judging from the description of how a Halogen
bulb works, I suspect you have a justifiable concern.



--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Arfa Daily wrote:

I too have a thin plastic cable in there. There was a good reason that
I changed it apart from the intermittency. Over the years, it has had
a lot of 'half-arsed' repairs done to it. I'm sure if you have one,
you know exactly what I mean. It's half past two, and the guy is
coming to pick up his amplifier that you have assured him will be
ready at half past four, and the bench light starts going on and off
... Well, a long time ago, some silicon sheathed heat-resistant wire
had gone into the lampholder, and been joined to the feed cable (via
the pressel switch bypass ...!!) with a bit of plastic choc-bloc. Yes,
I know, but I didn't have a ceramic one to hand.

Ooo shudder !

Anyway, it had been fine until I started using these small very hot
bulbs in it, whereupon the nylon insulation on the bloc had crisped
up. Well, a couple of weeks ago, I had one hand on the (earthed)
chassis of an amp I was working on (no, it wasn't plugged into the
bench isolation tranny as it should have been !) and I grabbed the
Anglepoise shade to pull it into a more convenient position. A
microsecond later, the air turned blue as a stream of profanity flowed
from my mouth ...

I must admit I don't plug mine into the isolated side ! Doesn't/didn't
yours have an earth connection then ? Mine does and had one from new !

The crisped up insulation on the choc-bloc had left a mains leakage
path to the metal shade. I decided there and then that no such thing
was going to happen again, so I have now rewired it with a thin
three-core cable, and grounded the metalwork to mains earth, via the
earth connector on the brass lampholder. Silicon sleeving has also
been fitted to the wire ends in an effort to proof them at least some,
against future heat problems.

I've seen electric heaters repaired with those plastic choc-blocks put
in them. I once had an old lady ask me to look at one. She said it
smells funny and there is something dripping out of the back. The
plastic surround had almost compleatly gone and the connections were
hanging in mid air. I had a go at the guy who repaired it and was
un-politely told to sod off........ Sadley there weren't the consumer
protections in those days !

I've got to admit that the shock I got from the setup was a bit of a
wakeup call, as it's often the case that your forehead brushes agains
the lamp shade, as you try to stick your head inside some recalcitrant
item that's on the bench for repair. At least now, if there should be
any future leakage issues, it should just whack the RCD out.

Arfa

Its a good thing you didn't touch it with your forehead ! I can't
imagine the possible injury it could have caused. At least it
shouldn't happen again.


--
Best Regards:
Baron.

Jeff Liebermann wrote:

On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention
?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp. I have a few here and
they all specify 60 watts maximum. I guess that applies only to the
old large bulbs.

I don't know about Arfa's lamp, but mine never had any warnings about
bulb size ! I do know that at a pinch you could get a 150 W bulb in
there. Indeed on the odd occasion I have done just that.
Interestingly I recall that the light output was actually poorer with
the bigger bulb. Probably because the filament was considerably
further away from the shade/reflector.

--
Best Regards:
Baron.

In article ,
Baron wrote:
I've seen electric heaters repaired with those plastic choc-blocks put
in them. I once had an old lady ask me to look at one. She said it
smells funny and there is something dripping out of the back. The
plastic surround had almost compleatly gone and the connections were
hanging in mid air. I had a go at the guy who repaired it and was
un-politely told to sod off........ Sadley there weren't the consumer
protections in those days !

There's no difference from a choc block than any other screw connector -
like those found in sockets, etc. Make a poor connection or use an
incorrectly rated one and it *will* give trouble.

--
*Certain frogs can be frozen solid, then thawed, and survive *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote in message
...
In article ,
Baron wrote:
I've seen electric heaters repaired with those plastic choc-blocks put
in them. I once had an old lady ask me to look at one. She said it
smells funny and there is something dripping out of the back. The
plastic surround had almost compleatly gone and the connections were
hanging in mid air. I had a go at the guy who repaired it and was
un-politely told to sod off........ Sadley there weren't the consumer
protections in those days !

There's no difference from a choc block than any other screw connector -
like those found in sockets, etc. Make a poor connection or use an
incorrectly rated one and it *will* give trouble.

--
*Certain frogs can be frozen solid, then thawed, and survive *

Dave Plowman London SW
To e-mail, change noise into sound.


One general thing to be aware of these Anglepoise lamps. Well the stronger ,
older , all metal ones.
Make sure all the little rubber grommets are present and correct, not
perished, at each of the channel holes that the mains cable passes through.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

In article ,
N_Cook wrote:
One general thing to be aware of these Anglepoise lamps. Well the
stronger , older , all metal ones. Make sure all the little rubber
grommets are present and correct, not perished, at each of the channel
holes that the mains cable passes through.

If it's old enough it will have silk covered rubber cable too - which
perishes.

--
*What was the best thing before sliced bread? *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

In article ,
Baron wrote:
I've seen electric heaters repaired with those plastic choc-blocks
put
in them. I once had an old lady ask me to look at one. She said it
smells funny and there is something dripping out of the back. The
plastic surround had almost compleatly gone and the connections were
hanging in mid air. I had a go at the guy who repaired it and was
un-politely told to sod off........ Sadley there weren't the
consumer protections in those days !

There's no difference from a choc block than any other screw connector
- like those found in sockets, etc. Make a poor connection or use an
incorrectly rated one and it *will* give trouble.

I couldn't agree more !

However I was referring to the fact that some Id10T had replaced the
original ceramic terminal block with a plastic one ! The fact that the
plastic over the course of a couple of weeks had just melted away with
the heat, rather than just a bad joint. Its likely that the original
had one or more seized or broken grub screws, leading to its
replacement.

--
Best Regards:
Baron.

Dave Plowman (News) wrote:

In article ,
N_Cook wrote:
One general thing to be aware of these Anglepoise lamps. Well the
stronger , older , all metal ones. Make sure all the little rubber
grommets are present and correct, not perished, at each of the
channel holes that the mains cable passes through.

If it's old enough it will have silk covered rubber cable too - which
perishes.

Yes mine did ! That was one of the reasons that I used cotton braided
electric iron flex as the first replacement. I found it less durable
than the original.

--
Best Regards:
Baron.

"N_Cook" wrote in message
...
Dave Plowman (News) wrote in message
...
In article ,
Baron wrote:
I've seen electric heaters repaired with those plastic choc-blocks put
in them. I once had an old lady ask me to look at one. She said it
smells funny and there is something dripping out of the back. The
plastic surround had almost compleatly gone and the connections were
hanging in mid air. I had a go at the guy who repaired it and was
un-politely told to sod off........ Sadley there weren't the consumer
protections in those days !

There's no difference from a choc block than any other screw connector -
like those found in sockets, etc. Make a poor connection or use an
incorrectly rated one and it *will* give trouble.

--
*Certain frogs can be frozen solid, then thawed, and survive *

Dave Plowman London SW
To e-mail, change noise into sound.


One general thing to be aware of these Anglepoise lamps. Well the stronger
,
older , all metal ones.
Make sure all the little rubber grommets are present and correct, not
perished, at each of the channel holes that the mains cable passes
through.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



I was a little concerned that these would not still fit, when I put the 3
core cable in, but they did, just fine.

And to Baron. I've had the thing a long long time. It's an orange one that
came from BHS originally, but a genuine Terry's Anglepoise, none-the-less.
Before that, I had the even earlier one with the black 'flying saucer'
shade. I can't remember what happened to that one. Over the years, it has
had much work done on it, but I'm pretty sure that it never had anything
other than a 2 core plastic cable on it. I can't imagine that I would ever
have replaced a three core with a 2 core. The old black one had plaited
cotton-covered rubber cable as I recall, but I still don't remember that one
being earthed, either.

Arfa

"Jeff Liebermann" wrote in message
...
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp.

You're mis-understanding me, I think. I'm not using a 75 or 100 watt bulb.
I'm using a 60 watt bulb, as specified for the lamp, and always have done.
Up until now, they have always been the 'standard' tennis ball sized type.
The smaller ones that I have been buying lately, are still rated at 60
watts, but in my opinion, put out the *heat* of a standard-sized 100 watt
bulb.

Arfa

In message , Arfa Daily
writes

"Jeff Liebermann" wrote in message
.. .
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp.

You're mis-understanding me, I think. I'm not using a 75 or 100 watt bulb.
I'm using a 60 watt bulb, as specified for the lamp, and always have done.
Up until now, they have always been the 'standard' tennis ball sized type.
The smaller ones that I have been buying lately, are still rated at 60
watts, but in my opinion, put out the *heat* of a standard-sized 100 watt
bulb.

Arfa

I haven't been following the thread, so apologies if this explanation
has been offered earlier.

I'm guessing, but I reckon that smaller sized bulb may be hotter
because:
(a) The filament may be physically smaller (squeezed in more, and coiled
up tighter). Some parts of the filament may be obstructing the path of
the light from other parts. Similarly, the path for radiated heat may be
being obstructed. As a result, the filament may be less efficient (less
light output, but more heat).
(a) The glass bulb is closer to the hot filament.
(b) The glass bulb has quite a lot less surface area available to
dissipate the heat.

What do you think?
--
Ian

On Sun, 6 Jul 2008 15:18:28 +0100, "Arfa Daily"
wrote:


"Jeff Liebermann" wrote in message
.. .
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp.

You're mis-understanding me, I think. I'm not using a 75 or 100 watt bulb.
I'm using a 60 watt bulb, as specified for the lamp, and always have done.
Up until now, they have always been the 'standard' tennis ball sized type.
The smaller ones that I have been buying lately, are still rated at 60
watts, but in my opinion, put out the *heat* of a standard-sized 100 watt
bulb.

Sorry. I misread your comments. I'm not sure where I got the 75 to
100 watt bulb.

Despite my screwup, the rest is still applicable. Did you read:
http://rabi.phys.virginia.edu/HTW/page1.php?QNum=1042
If the smaller bulbs are halogen filled, that would explain the
increased temperature.

Also, note that the easiest way to increase the temperature of a light
bulb surface is to simply decrease the surface area of the bulb. It's
exactly like a heat sink. If you have a heat source that beleches
some number of watts, a large surface area will be cooler than a small
surface area. Since the article indicates that halogen bulbs REQUIRE
a much hotter bulb temperature, a smaller bulb diameter, with a
corresponding smaller surface area, will be the way to accomplish
that. Methinks it all fits.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
wrote:

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.

Lost in this conversation is the fact that you claim that both the old
and new bulbs have been 60 Watts. Now, if that's true, then there's no
more power available from the new 60 W lamps than there was from the
old 60 W lamps.

Halogen lamps, while they DO have much hotter envelopes, convert
electrical power into visible lighte somewhat more efficiently, so
that should make the shade run slightly cooler, if anything. I would
expect this effect to be small.

Certainly a smaller 60 W bulb will run at a higher glass envelope
temperature, but that envelope will be farther from the shade,
assuming that they both got mounted on the same centers. The end
result is that there will be no difference in the radiant heating of
the shade.

The confusion here seems to be the common one between temperature and
heat. Cram the same amount of heat into a smaller amount of material
and you'll get a higher temperature, but in this case, the shade has
remained the same, so the amount of heat energy collected should be
the same, and the resulting temperature should also be the same.

It may help to think of heat and temperature as having electrical
analogs in charge and voltage.

Really, there are only 2 possible conclusions: Either the new bulb is
actually higher wattage than the old one, or the perception of a
hotter shade is mistaken.

Separate from this is heat conduction thru the base of the bulb. If
the bulb is shorter and hotter, then it will likely conduct more heat
into the socket. Halogen sockets are generally ceramic or some rather
special high temp plastic in order to deal with this, so putting a
halogen bulb in a standard socket will always result in a destroyed
socket.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

"Jim Adney" wrote in message
...
On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
wrote:

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.

Lost in this conversation is the fact that you claim that both the old
and new bulbs have been 60 Watts. Now, if that's true, then there's no
more power available from the new 60 W lamps than there was from the
old 60 W lamps.

Halogen lamps, while they DO have much hotter envelopes, convert
electrical power into visible lighte somewhat more efficiently, so
that should make the shade run slightly cooler, if anything. I would
expect this effect to be small.

Certainly a smaller 60 W bulb will run at a higher glass envelope
temperature, but that envelope will be farther from the shade,
assuming that they both got mounted on the same centers. The end
result is that there will be no difference in the radiant heating of
the shade.

The confusion here seems to be the common one between temperature and
heat. Cram the same amount of heat into a smaller amount of material
and you'll get a higher temperature, but in this case, the shade has
remained the same, so the amount of heat energy collected should be
the same, and the resulting temperature should also be the same.

It may help to think of heat and temperature as having electrical
analogs in charge and voltage.

Really, there are only 2 possible conclusions: Either the new bulb is
actually higher wattage than the old one, or the perception of a
hotter shade is mistaken.

Separate from this is heat conduction thru the base of the bulb. If
the bulb is shorter and hotter, then it will likely conduct more heat
into the socket. Halogen sockets are generally ceramic or some rather
special high temp plastic in order to deal with this, so putting a
halogen bulb in a standard socket will always result in a destroyed
socket.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

OK. The bulb does not claim to be a halogen type. It was sold as a 'bog
standard' light bulb. It looks like a standard light bulb. It is stamped 60
watts on the packet, and on the bulb itself. The glass envelope and bulb in
general, is identical in every way to what any of us would recognise as a
'standard' incandescent light bulb given, of course, the obvious difference
between a UK bi-pad bayonet cap, and a U.S. edison screw cap. However, it
has one major difference in that instead of the glass envelope being the
size of a tennis ball, it's more like the size of a pool ball. When
installed in my bench light, which is the only 'closed in' place that I've
used one so far, I did not notice any change in light output from any other
60 watt bulb that I have used in the light. Bear in mind that this light is
used every working day to illuminate whatever piece of kit I am working on,
and has been for the last 20 years, so I am pretty confidant that I know its
'normal' operating characteristics.

So, if we believe the rating stamped on both the bulb itself, and its box,
and you are prepared to believe me when I tell you that with this bulb
fitted, the temperature of the shade was a whole heap hotter, then
somewhere, there must be another explanation than the two that you believe
are the only possibilities. There must be a greater degree of heat being
conducted into the base cap, in order for the temperature to have been
raised to the point where the insulation material within the lamp itself's
base, to have started to fry itself and to have destroyed the connection
pad, which is where this thread started from. There must be considerably
more heat steaming off the bulb itself, to have raised the temperature in
the upper part of the shade, to the point where the nylon insulation around
the choc bloc which was located there, has fried. That piece of choc bloc
had been there for a couple of years, and trust me, before fitting this
bulb, it was not even discoloured, let alone crisped.

The physical contact area between the brass lamp holder, and the bracket to
which it is attached, is small, so it would seem unlikely that heat
conduction is playing much of a part in raising the temperature of the
shade. So that would leave only radiation as the mechanism for raising the
shade's temperature. I'm pretty sure that it must be a combination of the
area of the glass envelope being - what, I don't know, 30% smaller maybe? -
making for a less efficient radiator, and exacerbation of this by that glass
being nearer to the filament.

It still seems to me that this has potentially far-reaching consequences
under the right (wrong?) circumstances. The bulb was a B&Q own brand BTW. I
don't have any more in stock at the moment, but I will try to get to the
store and pick some more up, and do some further tests and measurements.

Arfa

"Ian Jackson" wrote in message
...
In message , Arfa Daily
writes

"Jeff Liebermann" wrote in message
. ..
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
wrote:

Potential fire hazard, or am
I just being paranoid ? Does this need bringing to someone's attention ?

You might have a point, however I find it odd that you're using a 75
or 100 watt incandescent bulb in a desk lamp.

You're mis-understanding me, I think. I'm not using a 75 or 100 watt bulb.
I'm using a 60 watt bulb, as specified for the lamp, and always have done.
Up until now, they have always been the 'standard' tennis ball sized type.
The smaller ones that I have been buying lately, are still rated at 60
watts, but in my opinion, put out the *heat* of a standard-sized 100 watt
bulb.

Arfa

I haven't been following the thread, so apologies if this explanation has
been offered earlier.

I'm guessing, but I reckon that smaller sized bulb may be hotter because:
(a) The filament may be physically smaller (squeezed in more, and coiled
up tighter). Some parts of the filament may be obstructing the path of the
light from other parts. Similarly, the path for radiated heat may be being
obstructed. As a result, the filament may be less efficient (less light
output, but more heat).
(a) The glass bulb is closer to the hot filament.
(b) The glass bulb has quite a lot less surface area available to
dissipate the heat.

What do you think?
--
Ian

Yes, all valid thoughts. See my further discussions of it all in my reply
below to Jim

Arfa

On Mon, 7 Jul 2008 01:28:51 +0100 "Arfa Daily"
wrote:

So, if we believe the rating stamped on both the bulb itself, and its box,
and you are prepared to believe me when I tell you that with this bulb
fitted, the temperature of the shade was a whole heap hotter, then
somewhere, there must be another explanation than the two that you believe
are the only possibilities.

I believe everything you've told us about the bulbs. I have no reason
not to, but 60 Watts is still just 60 Watts.

There's no way to get more heat out of it than that. So either the old
60 was actually less than 60 or the new 60 is more than 60 (or both.)
Or you're mistaken about the new ones running hotter, which I agree is
the less likely option.

One other possibility occurred to me, and that is that your socket
chose this moment to become resistive, which could have raised the
total power above 60 Watts and concentrated that extra power
dissipation in the socket - consistent with your observations. I'm not
familiar with the socket you describe, so maybe you can judge the
likelyhood of this. I suspect that if this had happened, the light
output would have been affected and you would have noticed.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

"Arfa Daily" wrote in message
...

"Jim Adney" wrote in message
...
On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
wrote:

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.

Lost in this conversation is the fact that you claim that both the old
and new bulbs have been 60 Watts. Now, if that's true, then there's no
more power available from the new 60 W lamps than there was from the
old 60 W lamps.

Halogen lamps, while they DO have much hotter envelopes, convert
electrical power into visible lighte somewhat more efficiently, so
that should make the shade run slightly cooler, if anything. I would
expect this effect to be small.

Certainly a smaller 60 W bulb will run at a higher glass envelope
temperature, but that envelope will be farther from the shade,
assuming that they both got mounted on the same centers. The end
result is that there will be no difference in the radiant heating of
the shade.

The confusion here seems to be the common one between temperature and
heat. Cram the same amount of heat into a smaller amount of material
and you'll get a higher temperature, but in this case, the shade has
remained the same, so the amount of heat energy collected should be
the same, and the resulting temperature should also be the same.

It may help to think of heat and temperature as having electrical
analogs in charge and voltage.

Really, there are only 2 possible conclusions: Either the new bulb is
actually higher wattage than the old one, or the perception of a
hotter shade is mistaken.

Separate from this is heat conduction thru the base of the bulb. If
the bulb is shorter and hotter, then it will likely conduct more heat
into the socket. Halogen sockets are generally ceramic or some rather
special high temp plastic in order to deal with this, so putting a
halogen bulb in a standard socket will always result in a destroyed
socket.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

OK. The bulb does not claim to be a halogen type. It was sold as a 'bog
standard' light bulb. It looks like a standard light bulb. It is stamped 60
watts on the packet, and on the bulb itself. The glass envelope and bulb in
general, is identical in every way to what any of us would recognise as a
'standard' incandescent light bulb given, of course, the obvious difference
between a UK bi-pad bayonet cap, and a U.S. edison screw cap. However, it has
one major difference in that instead of the glass envelope being the size of a
tennis ball, it's more like the size of a pool ball. When installed in my
bench light, which is the only 'closed in' place that I've used one so far, I
did not notice any change in light output from any other 60 watt bulb that I
have used in the light. Bear in mind that this light is used every working day
to illuminate whatever piece of kit I am working on, and has been for the last
20 years, so I am pretty confidant that I know its 'normal' operating
characteristics.

So, if we believe the rating stamped on both the bulb itself, and its box, and
you are prepared to believe me when I tell you that with this bulb fitted, the
temperature of the shade was a whole heap hotter, then somewhere, there must
be another explanation than the two that you believe are the only
possibilities. There must be a greater degree of heat being conducted into the
base cap, in order for the temperature to have been raised to the point where
the insulation material within the lamp itself's base, to have started to fry
itself and to have destroyed the connection pad, which is where this thread
started from. There must be considerably more heat steaming off the bulb
itself, to have raised the temperature in the upper part of the shade, to the
point where the nylon insulation around the choc bloc which was located there,
has fried. That piece of choc bloc had been there for a couple of years, and
trust me, before fitting this bulb, it was not even discoloured, let alone
crisped.

The physical contact area between the brass lamp holder, and the bracket to
which it is attached, is small, so it would seem unlikely that heat conduction
is playing much of a part in raising the temperature of the shade. So that
would leave only radiation as the mechanism for raising the shade's
temperature. I'm pretty sure that it must be a combination of the area of the
glass envelope being - what, I don't know, 30% smaller maybe? - making for a
less efficient radiator, and exacerbation of this by that glass being nearer
to the filament.

It still seems to me that this has potentially far-reaching consequences under
the right (wrong?) circumstances. The bulb was a B&Q own brand BTW. I don't
have any more in stock at the moment, but I will try to get to the store and
pick some more up, and do some further tests and measurements.

Arfa


I've been following this thread rather loosely for the past several days, so
please pardon me if I repeat previously addressed thoughts.

Arfa, I understand that you've stated that you're using lamps labeled as 60-watt
in your fixture. Have you actually measured the power consumed (for instance,
using a Kill-a-Watt or similar meter) by the lamps? It's a possibility that the
lamps have been mislabeled, and you actually have 75- or 90-watt lamps instead
of 60-watt lamps.

Since an operating incandescent lamp is essentially a resistive element, the
power consumed should be RMS power, which is the heating value of the power.
Sixty watts RMS into a resistive element should produce the same amount of heat,
whether it's in a large glass bulb or a small glass bulb. The temperature of
the bulb might be higher in a small lamp because it has a smaller radiating
surface. Power that is concentrated in a small area will have a higher
temperature than the same power that has been spread over a larger area.

Is the radiating surface area of the new lamps small enough to cause the
increase in temperature that you're experiencing?? I suppose the math could be
done to derive the rise in temperature of your new lamps... would be interesting
to see the results.

My ending thought on the issue is that, IMHO, the telling story would be in the
reading of a power meter in the circuit. If you don't have a power meter such a
the Kill-a-Watt, then you could measure it directly with a voltmeter and
ammeter. V * I = P no need to measure phase since it's essentially a resistor.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Experience: What you get when you don't get what you want

On Mon, 7 Jul 2008 01:28:51 +0100, "Arfa Daily"
wrote:


OK. The bulb does not claim to be a halogen type. It was sold as a 'bog
standard' light bulb. It looks like a standard light bulb. It is stamped 60
watts on the packet, and on the bulb itself.

Does it have one of these labels?
http://www.energysavingtrust.org.uk/energy_saving_products/other_energy_labels/the_eu_energy_label/
http://www.thelightbulbshop.co.uk/EnergyLabels.htm
If so, what are the numbers? We don't have anything similar in the US
so it would helpful if you could supply the numbers for an "ordinary"
light 60w bulb. Note that halogen are in class "D" while ordinary
bulbs are "E" or "F".

However, it
has one major difference in that instead of the glass envelope being the
size of a tennis ball, it's more like the size of a pool ball.

Could I trouble you to measure the approximate diameters? I want to
calculate the relative surface areas.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jim Adney wrote in message
...
On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
wrote:




Separate from this is heat conduction thru the base of the bulb. If
the bulb is shorter and hotter, then it will likely conduct more heat
into the socket. Halogen sockets are generally ceramic or some rather
special high temp plastic in order to deal with this, so putting a
halogen bulb in a standard socket will always result in a destroyed
socket.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------


I'd not appreciated that added effect with Ro80 "Apollo lander" shape bulbs.
The filament is perhaps twice the distance from the socket as the same
wattage but globular lamp. As well as reflecting forwards most of the
rearward-going heat and light.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

"Jim Adney" wrote in message
...
On Mon, 7 Jul 2008 01:28:51 +0100 "Arfa Daily"
wrote:

So, if we believe the rating stamped on both the bulb itself, and its box,
and you are prepared to believe me when I tell you that with this bulb
fitted, the temperature of the shade was a whole heap hotter, then
somewhere, there must be another explanation than the two that you believe
are the only possibilities.

I believe everything you've told us about the bulbs. I have no reason
not to, but 60 Watts is still just 60 Watts.

There's no way to get more heat out of it than that. So either the old
60 was actually less than 60 or the new 60 is more than 60 (or both.)
Or you're mistaken about the new ones running hotter, which I agree is
the less likely option.

Presumably though, temperature will rise, both at the glass surface and the
surrounding air, if that heat is not being radiated away as quickly as with
the older design ?


One other possibility occurred to me, and that is that your socket
chose this moment to become resistive, which could have raised the
total power above 60 Watts and concentrated that extra power
dissipation in the socket - consistent with your observations. I'm not
familiar with the socket you describe, so maybe you can judge the
likelyhood of this. I suspect that if this had happened, the light
output would have been affected and you would have noticed.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

Plus I did say earlier that the socket was replaced fairly recently, and is
working just fine again now without one of those bulbs in it.

Here is a picture of the actual item so you will now know for ever, what a
UK bayonet cap looks like !

http://www.comparestoreprices.co.uk/...-pack-of-4.jpg

and here's one on a CFL. which shows the connection pads very clearly.

http://upload.wikimedia.org/wikipedi...ayonet-Cap.jpg

The B&Q bulb got hot enough to fry that black resin stuff, and completely
destroy one of the connector pads which are made from (lead-free now, I
guess) solder.

Arfa

OK. The bulb does not claim to be a halogen type. It was sold as a 'bog
standard' light bulb. It looks like a standard light bulb. It is stamped
60 watts on the packet, and on the bulb itself. The glass envelope and
bulb in general, is identical in every way to what any of us would
recognise as a 'standard' incandescent light bulb given, of course, the
obvious difference between a UK bi-pad bayonet cap, and a U.S. edison
screw cap. However, it has one major difference in that instead of the
glass envelope being the size of a tennis ball, it's more like the size
of a pool ball. When installed in my bench light, which is the only
'closed in' place that I've used one so far, I did not notice any change
in light output from any other 60 watt bulb that I have used in the
light. Bear in mind that this light is used every working day to
illuminate whatever piece of kit I am working on, and has been for the
last 20 years, so I am pretty confidant that I know its 'normal'
operating characteristics.

So, if we believe the rating stamped on both the bulb itself, and its
box, and you are prepared to believe me when I tell you that with this
bulb fitted, the temperature of the shade was a whole heap hotter, then
somewhere, there must be another explanation than the two that you
believe are the only possibilities. There must be a greater degree of
heat being conducted into the base cap, in order for the temperature to
have been raised to the point where the insulation material within the
lamp itself's base, to have started to fry itself and to have destroyed
the connection pad, which is where this thread started from. There must
be considerably more heat steaming off the bulb itself, to have raised
the temperature in the upper part of the shade, to the point where the
nylon insulation around the choc bloc which was located there, has fried.
That piece of choc bloc had been there for a couple of years, and trust
me, before fitting this bulb, it was not even discoloured, let alone
crisped.

The physical contact area between the brass lamp holder, and the bracket
to which it is attached, is small, so it would seem unlikely that heat
conduction is playing much of a part in raising the temperature of the
shade. So that would leave only radiation as the mechanism for raising
the shade's temperature. I'm pretty sure that it must be a combination of
the area of the glass envelope being - what, I don't know, 30% smaller
maybe? - making for a less efficient radiator, and exacerbation of this
by that glass being nearer to the filament.

It still seems to me that this has potentially far-reaching consequences
under the right (wrong?) circumstances. The bulb was a B&Q own brand BTW.
I don't have any more in stock at the moment, but I will try to get to
the store and pick some more up, and do some further tests and
measurements.

Arfa


I've been following this thread rather loosely for the past several days,
so please pardon me if I repeat previously addressed thoughts.

Arfa, I understand that you've stated that you're using lamps labeled as
60-watt in your fixture. Have you actually measured the power consumed
(for instance, using a Kill-a-Watt or similar meter) by the lamps? It's a
possibility that the lamps have been mislabeled, and you actually have 75-
or 90-watt lamps instead of 60-watt lamps.

Since an operating incandescent lamp is essentially a resistive element,
the power consumed should be RMS power, which is the heating value of the
power. Sixty watts RMS into a resistive element should produce the same
amount of heat, whether it's in a large glass bulb or a small glass bulb.
The temperature of the bulb might be higher in a small lamp because it has
a smaller radiating surface. Power that is concentrated in a small area
will have a higher temperature than the same power that has been spread
over a larger area.

Is the radiating surface area of the new lamps small enough to cause the
increase in temperature that you're experiencing?? I suppose the math
could be done to derive the rise in temperature of your new lamps... would
be interesting to see the results.

My ending thought on the issue is that, IMHO, the telling story would be
in the reading of a power meter in the circuit. If you don't have a power
meter such a the Kill-a-Watt, then you could measure it directly with a
voltmeter and ammeter. V * I = P no need to measure phase since it's
essentially a resistor.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters
in the address)


Hi Dave
I haven't measured the actual power consumption of the new bulbs. A few
years ago, I would have been surprised if the figure quoted on a lamp was
not at least within say 5% accuracy, but these days, with the reduction in
integrity of just about everything, and the fact that much manufacturing is
now done in 'emerging' industrial countries, I would be less sure of that.
As to whether the new bulb's envelope is small enough to reduce the
dissipation of the heat by the amount noted, I'm not really a good enough
theoretical physicist to make a call of any real value, but given that this
appears to be the only mechanism by which this could be happening, I would
have to say that is probably the answer.

I don't dispute what has been said about 60 watts being 60 watts, or that
heat and temperature are not the same thing. However, radiation efficiency
is key to the relationship between the two, as we both know. A 60 watt amp
with a small silver heatsink on its output transistors will not get rid of
the unwanted heat anything like as well as if that heatsink is black, and
force air cooled.

For all I know, my bench lamp may be a 'special case', and the fitting of
the smaller bulb might just screw up the dynamics of the air circulation
within the shade. As anyone who knows the Terry's Anglepoise will agree, the
shade is not particularly well ventilated. Perhaps it would benefit from
having a ring of 5mm holes drilled around its top ... ??

Arfa
Experience: What you get when you don't get what you want

"Jeff Liebermann" wrote in message
...
On Mon, 7 Jul 2008 01:28:51 +0100, "Arfa Daily"
wrote:


OK. The bulb does not claim to be a halogen type. It was sold as a 'bog
standard' light bulb. It looks like a standard light bulb. It is stamped
60
watts on the packet, and on the bulb itself.

Does it have one of these labels?
http://www.energysavingtrust.org.uk/energy_saving_products/other_energy_labels/the_eu_energy_label/
http://www.thelightbulbshop.co.uk/EnergyLabels.htm
If so, what are the numbers? We don't have anything similar in the US
so it would helpful if you could supply the numbers for an "ordinary"
light 60w bulb. Note that halogen are in class "D" while ordinary
bulbs are "E" or "F".

However, it
has one major difference in that instead of the glass envelope being the
size of a tennis ball, it's more like the size of a pool ball.

Could I trouble you to measure the approximate diameters? I want to
calculate the relative surface areas.

--
Jeff Liebermann


The things I do for science !! I just had to rootle thru' the workshop bin
to locate the bulb which caused all the trouble in the first place. It is
clearly marked 60 watts, and has a CE approval also. I can't tell you what
the energy rating letter is, as I don't have any more on the shelf. I have
two other types from the same stable, and one of the boxes has an energy
rating on it, and one doesn't, so I'll have to look next time I am in the
store.

OK. On the diameters. Consider them for all practical purposes, to be a
sphere. The old was 60mm almost exactly, and the new, 50mm almost exactly,
measured with an electronic calliper, so reasonably accurate figures.

Arfa

"N_Cook" wrote in message
...
Jim Adney wrote in message
...
On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
wrote:




Separate from this is heat conduction thru the base of the bulb. If
the bulb is shorter and hotter, then it will likely conduct more heat
into the socket. Halogen sockets are generally ceramic or some rather
special high temp plastic in order to deal with this, so putting a
halogen bulb in a standard socket will always result in a destroyed
socket.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------


I'd not appreciated that added effect with Ro80 "Apollo lander" shape
bulbs.
The filament is perhaps twice the distance from the socket as the same
wattage but globular lamp. As well as reflecting forwards most of the
rearward-going heat and light.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



The R80 sounds the way to go from all angles. I'll pick one up next time I'm
in B&Q

Arfa

Ah, you see, what you really need is something that'll automatically
sense when the lamp is on, and turn on a cooling fan. I have just the
circuit... %^)

On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
wrote:

The things I do for science !!

Cease complaining. It's your question that I'm trying to answer.
Never mind that I don't know anything about light bulbs.

I have
two other types from the same stable, and one of the boxes has an energy
rating on it, and one doesn't, so I'll have to look next time I am in the
store.

Methinks there will be a difference in efficiency rating. If true,
that implies that the newer smaller bulb is really a Halogen filled
bulb, even though it's not marked as such.

OK. On the diameters. Consider them for all practical purposes, to be a
sphere. The old was 60mm almost exactly, and the new, 50mm almost exactly,
measured with an electronic calliper, so reasonably accurate figures.

Surface area of a sphere is 4Pi*r^2
Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
New = 4 * 3.14 * 2.5^2 = 78.5 sq cm
The new bulb has about 70% of the surface area as the old bulb.
However, I gotta dust off the college thermodyamics texts before I can
figure out the expected temperature rise given identical power
dissipations. I also gotta lookup the IR transmissivity of glass. The
things I do for science...




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"Jeff Liebermann" wrote in message
...
On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
wrote:

The things I do for science !!

Cease complaining. It's your question that I'm trying to answer.
Never mind that I don't know anything about light bulbs.

I have
two other types from the same stable, and one of the boxes has an energy
rating on it, and one doesn't, so I'll have to look next time I am in the
store.

Methinks there will be a difference in efficiency rating. If true,
that implies that the newer smaller bulb is really a Halogen filled
bulb, even though it's not marked as such.

OK. On the diameters. Consider them for all practical purposes, to be a
sphere. The old was 60mm almost exactly, and the new, 50mm almost exactly,
measured with an electronic calliper, so reasonably accurate figures.

Surface area of a sphere is 4Pi*r^2
Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
New = 4 * 3.14 * 2.5^2 = 78.5 sq cm
The new bulb has about 70% of the surface area as the old bulb.
However, I gotta dust off the college thermodyamics texts before I can
figure out the expected temperature rise given identical power
dissipations. I also gotta lookup the IR transmissivity of glass. The
things I do for science...


--
Jeff Liebermann

Quit complainin' !! I'm helping you figure all about light bulbs with my
question .... :-)

Arfa

On Mon, 07 Jul 2008 10:31:08 -0700, Jeff Liebermann
wrote:

On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
wrote:

The things I do for science !!



Surface area of a sphere is 4Pi*r^2
Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
New = 4 * 3.14 * 2.5^2 = 78.5 sq cm
The new bulb has about 70% of the surface area as the old bulb.
However, I gotta dust off the college thermodyamics texts before I can
figure out the expected temperature rise given identical power
dissipations. I also gotta lookup the IR transmissivity of glass. The
things I do for science...

The other unknown factor is the lamp efficiency. So how much is
going out as light, and how much as heat. A small change in this
ratio will certainly have an effect on the heating effect even with
identical sized globes.

Peter

In article ,
Jeff Liebermann wrote:

On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
wrote:

snippage

Methinks there will be a difference in efficiency rating. If true,
that implies that the newer smaller bulb is really a Halogen filled
bulb, even though it's not marked as such.

OK. On the diameters. Consider them for all practical purposes, to be a
sphere. The old was 60mm almost exactly, and the new, 50mm almost exactly,
measured with an electronic calliper, so reasonably accurate figures.

Surface area of a sphere is 4Pi*r^2
Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
New = 4 * 3.14 * 2.5^2 = 78.5 sq cm
The new bulb has about 70% of the surface area as the old bulb.
However, I gotta dust off the college thermodyamics texts before I can
figure out the expected temperature rise given identical power
dissipations. I also gotta lookup the IR transmissivity of glass. The
things I do for science...

I'd be inclined to think a bigger difference could be the relative heat
dissipation via conduction through the base vs. convection through the
glass envelope. If the newer bulb has significantly heftier and/or
shorter leads for the filament, the metal base might be getting
significantly hotter and conducting more heat to the socket.

Incandescent bulbs are inefficient enough, regardless of construction,
that any moderate efficiency gains would have no readily observable
impact on heat output--or, put another way, any improvements that would
reduce the heat output by a nontrivial amount would also produce a bulb
that is obviously much brighter. According to Wikipedia, something like
2% of the electrical energy consumed is converted to visible light.

--
Andrew Erickson

"He is no fool who gives what he cannot keep to gain that which he cannot
lose." -- Jim Elliot

"Andrew Erickson" wrote in message
...
In article ,
Jeff Liebermann wrote:

On Mon, 7 Jul 2008 09:53:39 +0100, "Arfa Daily"
wrote:

snippage

Methinks there will be a difference in efficiency rating. If true,
that implies that the newer smaller bulb is really a Halogen filled
bulb, even though it's not marked as such.

OK. On the diameters. Consider them for all practical purposes, to be a
sphere. The old was 60mm almost exactly, and the new, 50mm almost
exactly,
measured with an electronic calliper, so reasonably accurate figures.

Surface area of a sphere is 4Pi*r^2
Old = 4 * 3.14 * 3.0^2 = 113.0 sq cm
New = 4 * 3.14 * 2.5^2 = 78.5 sq cm
The new bulb has about 70% of the surface area as the old bulb.
However, I gotta dust off the college thermodyamics texts before I can
figure out the expected temperature rise given identical power
dissipations. I also gotta lookup the IR transmissivity of glass. The
things I do for science...

I'd be inclined to think a bigger difference could be the relative heat
dissipation via conduction through the base vs. convection through the
glass envelope. If the newer bulb has significantly heftier and/or
shorter leads for the filament, the metal base might be getting
significantly hotter and conducting more heat to the socket.

Incandescent bulbs are inefficient enough, regardless of construction,
that any moderate efficiency gains would have no readily observable
impact on heat output--or, put another way, any improvements that would
reduce the heat output by a nontrivial amount would also produce a bulb
that is obviously much brighter. According to Wikipedia, something like
2% of the electrical energy consumed is converted to visible light.

--
Andrew Erickson



Peter, Andrew. Thanks for your input. Both good thoughts.

Arfa