Arfa Daily <arfa.daily at (no spam) ntlworld.com> wrote in message
news:y4ebk.387$jB5.114 at (no spam) newsfe05.ams2...
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/

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

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 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.

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.

"Baron" <baron.nospam at (no spam) linuxmaniac.nospam.net> wrote in message
news:g4lfhd$75u$1 at (no spam) registered.motzarella.org...
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

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.

On Fri, 4 Jul 2008 01:23:49 +0100, "Arfa Daily"
arfa.daily at (no spam) ntlworld.com> 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 jeffl at (no spam) cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

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

"Jeff Liebermann" <jeffl at (no spam) cruzio.com> wrote in message
news:tbf0745m65iugupkjtnnasnbe2vf777j6q at (no spam) 4ax.com...
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
arfa.daily at (no spam) ntlworld.com> 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.

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.

On Fri, 4 Jul 2008 01:23:49 +0100 "Arfa Daily"
arfa.daily at (no spam) ntlworld.com> 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 jadney at (no spam) vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

In message <Wu4ck.249528$1B6.13899 at (no spam) newsfe21.ams2>, Arfa Daily
arfa.daily at (no spam) ntlworld.com> writes

"Jeff Liebermann" <jeffl at (no spam) cruzio.com> wrote in message
news:tbf0745m65iugupkjtnnasnbe2vf777j6q at (no spam) 4ax.com...
On Sun, 6 Jul 2008 02:08:27 +0100, "Arfa Daily"
arfa.daily at (no spam) ntlworld.com> 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