Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

--
Cheers, Rob

In article ,
RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

CFLs will have a vastly shortened life is the electronics in the base of
the bulb get too hot. Hence the CFL rating given on your fitting. A LED
might be a better bet.

--
*I'm reading a book about anti-gravity. I just can't put it down.*

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

On Wednesday, 20 December 2017 10:07:53 UTC, RJH wrote:

Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

60w rating is for the safety of the angled poison.
11W rating is for the survival of the lightbulb.
23W CFL is going to be short lived in there.


NT

RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)


Well logically you would think that its all about the ability of a shade
to dissipate heat so that a shade rated for 60W should be safe with any
bulb up to 60W irrespective of the technology used to generate the light.

Where the difference lies is probably in the thermal sensitivity of the
bulb. Incandescent bulbs are very heat tolerant, compact fluorescents much
less so. So the shade isnt going to catch fire but the bulb life may be
much shorter than expected.

Tim

--
Please don't feed the trolls

In article ,
RJH writes:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

A GLS filament lamp is designed to run at around 200C.
A CFL is designed to run the tube at around 100C, so max power rating
is less. The life of the electronics in the CFL is very temperature
dependant. In a well cooled/ventilated fitting, the tube will generally
reach full life and fail when the emission material is all lost from
the electrodes. When run hotter, the life of the electronic control
gear reduces - typically it halves for every 10C temperature rise, and
if run hot, the electronics will probably fail before the tube does.

So the only consequence is likely to be shorter life due to the
integral electronics failing earlier.

An LED flood lamp or spot lamp might be a better choice because a
lower power LED (less than half that of the CFL) will still get you
more light where you want it. LED's are even less able to
withstand high tempertures than CFL's, so its benefit derives from
being twice as efficient, and being natuarally directional without
spilling light where it's not wanted. CFL's are particularly
inefficient in lamps or fittings which direct the light, because
large omni-directional light sources and compact reflectors don't
work well together, so in this case the LED is going to be well
more than twice as efficient.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 20/12/2017 10:07, RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

It will quickly cook its control electronics and fail.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

That is about right. The 60W incandescent loses most of its heat as
invisible IR radiation which gets away quickly and the bulb envelope
still gets mad hot but nowhere near the melting point of glass.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils. Its life will be significantly shortened by
running it hot in a fixture designed for incandescents.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

Halogen desk lamps are even more dodgy. They really will burn the
building down if misused or something goes badly wrong. Shards of red
hot glass go everywhere if one explodes uncontained.

--
Regards,
Martin Brown

In article
,
Tim+ wrote:
Well logically you would think that it‘s all about the ability of a shade
to dissipate heat so that a shade rated for 60W should be safe with any
bulb up to 60W irrespective of the technology used to generate the light.

Not really. All it means is the construction of the fitting is suitable
for the heat generated by an incandescent lamp of that rating, and won't
melt or whatever. You can't expect a maker to have tested every lamp that
is or may be made. Especially since the electronics inside a CFL or LED
can vary by maker.

--
*I didn't drive my husband crazy -- I flew him there -- it was faster

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

In article ,
Huge wrote:
Dear Ghod, 23W? Get your vision checked. I'm typing this by the light
of a *5W* CFL in a (real) Anglepoise.

I can type in near darkness. But need a decent powerful light in an
anglepoise etc when looking for PCB etc faults. A 100w halogen is about
right.

--
*Save the whale - I'll have it for my supper*

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

On Wed, 20 Dec 2017 10:07:50 +0000, RJH coalesced
the vapors of human experience into a viable and meaningful
comprehension...

Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.


Let me guess, you work in the "public sector"?

--

Graham.
%Profound_observation%

On Wednesday, 20 December 2017 15:59:48 UTC, Graham. wrote:
On Wed, 20 Dec 2017 10:07:50 +0000, RJH coalesced
the vapors of human experience into a viable and meaningful
comprehension...

Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.


Let me guess, you work in the "public sector"?

We might have some 2KW oil filled radiators going spare, ideal if you want 700W of heating.

I'd not think such a low wattage cfl should get in any way warm at all. I
have one in a light here and I cannot tell its on after half an hour to the
touch, though the thing did look a little odd I'm told.
I wonder why its heating up unless its a cheap under rated chinese copy
that will fall to bits when the heat glue melts liike one I had from B/Q!
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"RJH" wrote in message
news
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a CH
radiator. But still hotter than I would expect. I've also noticed that the
sticker inside seems to indicate CFL max 11W, and incandescent max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

--
Cheers, Rob

Must be a pretty naff power unit if it gets hot at all, I'd suggest.My old
mazda never has.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...
On Wednesday, 20 December 2017 10:07:53 UTC, RJH wrote:

Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter
bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

60w rating is for the safety of the angled poison.
11W rating is for the survival of the lightbulb.
23W CFL is going to be short lived in there.


NT

On 20/12/2017 17:03, Brian Gaff wrote:
I'd not think such a low wattage cfl should get in any way warm at all. I
have one in a light here and I cannot tell its on after half an hour to the
touch, though the thing did look a little odd I'm told.

CFLs are not all that efficient and a 23W one is really pushing it for
efficiency and dissipation needed to stay cool enough to survive. In
anything other than free air with plenty of convection it will fail.

I wonder why its heating up unless its a cheap under rated chinese copy
that will fall to bits when the heat glue melts liike one I had from B/Q!
Brian

It is heating up because of losses in the power supply. Unlike filament
bulbs a CFL or LED has a rather low maximum operating temperature.

--
Regards,
Martin Brown

"RJH" wrote in message
news
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a CH
radiator. But still hotter than I would expect. I've also noticed that the
sticker inside seems to indicate CFL max 11W, and incandescent max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Why not put in a decent led bulb instead.

Slow work day . . . :-)

On 20/12/17 10:07, RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

you will lose about 75% of a CFL watt as heat and around 95% of a
filament lamp.

So yes, you will be losong a little under 18W from that CFL as apposed
to 55W from a 60W incandescent. Both are significanbt amounts of heat


--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

On 20/12/17 17:46, Martin Brown wrote:
On 20/12/2017 17:03, Brian Gaff wrote:
I'd not think such a low wattage cfl should get in any way warm at all. I
have one in a light here and I cannot tell its on after half an hour
to the
touch, though the thing did look a little odd I'm told.

CFLs are not all that efficient and a 23W one is really pushing it for
efficiency and dissipation needed to stay cool enough to survive. In
anything other than free air with plenty of convection it will fail.

Â* I wonder why its heating up unless its a cheap under rated chinese copy
that will fall to bits when the heat glue melts liike one I had from B/Q!
Â* Brian

It is heating up because of losses in the power supply. Unlike filament
bulbs a CFL or LED has a rather low maximum operating temperature.

What a staggeringly ignorant reply.

It is not heating up because of losses in the power supply. It is
heating up because of losses in the lamp.


--
Microsoft : the best reason to go to Linux that ever existed.

"Tim+" wrote in message
...
RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter
bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)


Well logically you would think that its all about the ability of a shade
to dissipate heat so that a shade rated for 60W should be safe with any
bulb up to 60W irrespective of the technology used to generate the light.

Nope, incandescent bulbs are fine with much higher temps than cfls.

Where the difference lies is probably in the thermal sensitivity of the
bulb.

No probably about it.

Incandescent bulbs are very heat tolerant, compact fluorescents
much less so. So the shade isnt going to catch fire but the bulb
life may be much shorter than expected.

Martin Brown wrote:
On 20/12/2017 17:03, Brian Gaff wrote:
I'd not think such a low wattage cfl should get in any way warm at all. I
have one in a light here and I cannot tell its on after half an hour to the
touch, though the thing did look a little odd I'm told.

CFLs are not all that efficient and a 23W one is really pushing it for
efficiency and dissipation needed to stay cool enough to survive. In
anything other than free air with plenty of convection it will fail.

I wonder why its heating up unless its a cheap under rated chinese copy
that will fall to bits when the heat glue melts liike one I had from B/Q!
Brian

It is heating up because of losses in the power supply. Unlike filament
bulbs a CFL or LED has a rather low maximum operating temperature.

If it's a 23 watt CFL then all of that 23 watts ends up as heat, some
(20% or so?) will be radiated away from the lamp as light and become
heat when absorbed elsewhere but most of that 23 watts will simply
heat up the lamp itself. Even if the power supply is 100% efficient
there will be 15 to 20 watts being lost in the lamp.

--
Chris Green
·

On Wed, 20 Dec 2017 08:36:21 -0800 (PST), whisky-dave
wrote:

snip

We might have some 2KW oil filled radiators going spare, ideal if you want 700W of heating.


Yes please. (they will probably be fine on their 1300W setting). ;-)

Cheers, T i m

On 20/12/2017 11:12, Huge wrote:
In article ,
RJH writes:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

Dear Ghod, 23W? Get your vision checked. I'm typing this by the light
of a *5W* CFL in a (real) Anglepoise. Annoyingly, I've not written the
install date on the bulb, which I usually do, but it's been in there
for sufficiently long that I can't recall when it was installed. Anglepoisen
have ventilation cutouts in the shade, so you should get some air flow
through it. The electronics package on mine is warm, but not too hot to
touch.

When it fails, I'll put an LED in it.

Getting your vision checked will not help , unless seriously
uncorrected. If your vision is poor in low light there is nothing that
can be medically done about it !
One of the problems of ageing and very annoying.

On Wed, 20 Dec 2017 10:07:50 +0000, RJH wrote:

Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter
bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

I wouldn't worry. The only consequence is that the 23W 1500Lm(?) CFL
will expire prematurely and my guess is that you'll land up being fed the
remaining stock to use it up so they can justify the purchase of LED
replacements of double the 65LPW efficacy of that 23W CFL (assuming it's
a 100W incandescent equivalent of 1500Lm).

The 11W CFL rating is rather pessimistic in my view (is the shade
blessed with ventilation holes around the bulb socket?). The reason for
the lower rating for CFL (and LED) is due to the much lower maximum lamp
temperature limits for this breed of energy efficient lamp compared to
the 200 deg C or so of an incandescent lamp.

The maximum junction temperature of silicon devices is 125 deg C. Since
a temperature gradient between the actual silicon transistor junctions
and the outside of its packaging is required for the heat energy produced
to flow into the surrounding environment via contact with air for circa
2W or less dissipation or via contact with a heatsink for wattages up to
the device's maximum dissipation rating, the external surfaces of the
base of a CFL may need to be no higher than 30 or more degrees lower than
this 125 deg C junction temperature limit.

The maximum dissipation ratings are usually quoted for an infinite
heatsink held to an ambient temperature of 25 deg C. Since practical
heatsinks (particularly in the case of CFL and LED GLS lamps) fall way
short of this ideal, the devices need to be de-rated from their maximum
wattage ratings to avoid permanent damage from over-heating.

Even when operating as switching devices where their losses are only a
small fraction of the input power going to the CFL tube or the LED array,
other components, including the CFL tube or LED array itself will raise
the temperature of the electronic ballast circuitry which could shorten
the life of any 105 deg C rated electrolytic caps typically used in all
but the most expensive examples of energy efficient lamps.

Since the air surrounding the lamp has to be warmed a few degrees above
ambient in order to set up a convective flow of cooling air, components
of the electronic ballast might well need to operate some 40 to 50 deg
hotter than the ambient temperature of the location being lit. An
indifferently ventilated light fitting might well increase this by a
further 10 to 20 degrees and a badly ventilated one by yet another 20
degrees. All of which leaves very little margin to avoid overheating the
electronic component parts of these lamps.

I can't recall the temperature limits for the typical blue LED chips
used in LED lamps but I suspect it's lower than that of silicon
transistor junctions and the limiting factor with most cheap LED lamps
using a lossless capacitor volt dropper ballast where almost all of the
waste heat is dissipated by the LED chips themselves.

If you don't fancy being subjected to frequent 23W CFL lamp
replacements, you can always nip into Home Bargains and spend £2.99 on a
12W 1500lm warm white or north light BC22 or LES 27 LED GLS lamp which
will run cooler than the notional 11W CFL that Anglepoisen light was
rated for. :-)

--
Johnny B Good

Robert wrote:

If your vision is poor in low light there is nothing that
can be medically done about it !

But a bright light will stop down your iris, so it acts somewhat like a
pinhole, assisting the eye's lens ...

On Wednesday, 20 December 2017 21:29:34 UTC, Johnny B Good wrote:

The maximum junction temperature of silicon devices is 125 deg C. Since

bzzt

a temperature gradient between the actual silicon transistor junctions
and the outside of its packaging is required for the heat energy produced
to flow into the surrounding environment via contact with air for circa
2W or less dissipation or via contact with a heatsink for wattages up to
the device's maximum dissipation rating, the external surfaces of the
base of a CFL may need to be no higher than 30 or more degrees lower than
this 125 deg C junction temperature limit.

The maximum dissipation ratings are usually quoted for an infinite
heatsink held to an ambient temperature of 25 deg C. Since practical
heatsinks (particularly in the case of CFL and LED GLS lamps) fall way
short of this ideal, the devices need to be de-rated from their maximum
wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!


NT

On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

--

On Wed, 20 Dec 2017 15:11:25 -0800 (PST), wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!

Care to point to a datasheet that shows that?

--

On Thu, 21 Dec 2017 11:16:40 +0000, The Other Mike
wrote:

On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

I'll have a go and say '105 DegC' cap and it would 'boil' (read not be
happy at ..) if 105 DegC was the temperature of the fitting and
therefore the temperature it was working at? Maybe the caps are more
susceptible to overtemp than most the other components?

I'm not confirming (scientifically) that that's what will happen but
that it seems logical as a suggestion to why such things might fail
prematurely if they are allowed to run hotter than they 'should'?

Cheers, T i m

Dave Plowman (News) wrote:
A 100w halogen is about
right.

What, in a 60W rated lamp?? Recklessly dangerous.

Tim

--
Please don't feed the trolls

On 20/12/17 21:29, Johnny B Good wrote:
The maximum junction temperature of silicon devices is 125 deg C.

No, it isn't. Its somwhere between 175 and 200C

But LEDS are of course not silicon devices....



--
"When a true genius appears in the world, you may know him by this sign,
that the dunces are all in confederacy against him."

Jonathan Swift.

On 21/12/17 11:16, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?


75C is standard commercial rating 125C is milspec. Silicon
Semiconductors are rated differently with 150-200C junction being the
critical temperature.

GaAs LEDS generally operate at sub boiling point junction temps, say 60-80C



--
€œit should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalins Communist era, nor in the Orwellian
utopia of 1984.€�

Vaclav Klaus

On 21/12/17 13:07, Tim+ wrote:
Dave Plowman (News) wrote:
A 100w halogen is about
right.

What, in a 60W rated lamp?? Recklessly dangerous.

Tim

Apperently its all OK if fitted by a fully paid up member of the sound
engineers and transverse ******s union, then its just fine...


--
I would rather have questions that cannot be answered...
....than to have answers that cannot be questioned

Richard Feynman

On 21/12/2017 11:16, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

That is about when the water based electrolyte in a cheap electrolytic
capacitor starts to turn into steam. Capacitors bulge after that until
the pressure relief bursting disc pops. You can get capacitors with
higher temperature ratings but I have never seen any in a lamp PSU.


https://en.wikipedia.org/wiki/Alumin...service_ life

Capacitor failure by drying out or boiling is invariably the weakest
link in the typical lamp driver PSU. There are capacitors rated for 125C
that have an MTBF of 2000 hrs which is no better than a filament bulb.

https://www.rapidonline.com/w-rth-at...0x12-5-61-4663

Quite difficult to test long term batch reliability too which is what
led to the dodgy capacitors with the misformulated stolen electrolyte
wrecking quite a lot of motherboards a decade or so back.

--
Regards,
Martin Brown

On Thursday, 21 December 2017 11:18:38 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

There's no evidence they'll boil but the electrolyte will dry out the higher the temperature, the 105 is the maxium working temeprature and at that they are gurenteed to last say 1000 or 2000 hours as a minium, you can get 130C caps if really are running at high temps.


--

On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


NT

In article
,
Tim+ wrote:
Dave Plowman (News) wrote:
A 100w halogen is about
right.

What, in a 60W rated lamp?? Recklessly dangerous.

No, Tim, unlike you I understand such things. If a fitting is rated at 60w
tungsten and not bright enough, I'd not have bought it in the first place.

However, for those that have, it might be possible to uprate the size of
the tungsten lamp it can take by fitting a more heat resistant holder.
Brass and ceramic rather than plastic.

It also depends on how long it is on for. The rating will be for
continuous use. If only for short periods, can likely be exceeded safely.

Basically, it is an idiot's guide. Ring any bells?

--
*A hangover is the wrath of grapes.

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

On Thursday, 21 December 2017 14:55:31 UTC, wrote:
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


NT

Not sure where it proves what you say it says.

On Wednesday, 20 December 2017 10:07:53 UTC, RJH wrote:
Can't quite think this through. Work has just fitted a 23W CFL in an
Anglepoise type desk lamp, replacing an 11W - I asked for a brighter bulb.

I've noticed that the shade gets very hot - maybe a little less than a
CH radiator. But still hotter than I would expect. I've also noticed
that the sticker inside seems to indicate CFL max 11W, and incandescent
max 60W.

I've pointed all this out to them, but the thinking seems to be that if
it's OK for 60W, then 23W will be fine, and they can't explain the 11W.

Is this about right? Work asked me to tell them if it gets worse - but
short of burning the building down, I'm not sure what sort of thing I
should be looking for.

Slow work day . . . :-)

--
Cheers, Rob

It's about lamp life.
Incandescent (filament)lamps can stand a lot more heat than CFLs.
(To do with the inbuilt electronics).
So the fitting has separate ratings for each of them.
Obviously it will be a lot hotter with incandescent.

In article ,
Tim+ wrote:
"Dave Plowman (News)" Wrote in message:
In article
,
Tim+ wrote:
Well logically you would think that it‘s all about the ability of a
shade to dissipate heat so that a shade rated for 60W should be safe
with any bulb up to 60W irrespective of the technology used to
generate the light.

Not really. All it means is the construction of the fitting is
suitable for the heat generated by an incandescent lamp of that
rating, and won't melt or whatever. You can't expect a maker to have
tested every lamp that is or may be made. Especially since the
electronics inside a CFL or LED can vary by maker.

-- *I didn't drive my husband crazy -- I flew him there -- it was
faster

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


Well thanks for snipping the rest of my reply that made it quite clear
that it isn't nearly as simple as that.

I snipped it because it was incorrect. And replaced it with an accurate
one.

BTW, you might get yourself a proper newsreader which 'snips' sigs. All
good ones do.

--
*What hair colour do they put on the driver's license of a bald man? *

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

On Thursday, 21 December 2017 14:25:28 UTC, whisky-dave wrote:
On Thursday, 21 December 2017 11:18:38 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 11:01:46 +0000, Martin Brown
wrote:

The CFL power supply will be stone dead at 105C when the electrolyte in
the PSU capacitors boils.

What temperature rating capacitor would you expect to be fitted and why would it
'boil' at 105 deg C?

There's no evidence they'll boil but the electrolyte will dry out the higher the temperature, the 105 is the maxium working temeprature and at that they are gurenteed to last say 1000 or 2000 hours as a minium, you can get 130C caps if really are running at high temps.

Dave is scientifically thorough, he doesn't just take your word for things, he requires evidence that water boils.


NT

In article 11d4a51f-9e27-4915-a5bf-53dd39799856
@googlegroups.com, says...

On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html


But the table on that page is clearly headed "Rating at 70°C"!



--

Terry

---
This email has been checked for viruses by AVG.
http://www.avg.com

wrote in message
...
On Thursday, 21 December 2017 11:18:44 UTC, The Other Mike wrote:
On Wed, 20 Dec 2017 15:11:25 -0800 (PST), tabbypurr wrote:

wattage ratings to avoid permanent damage from over-heating.

Some power resistors are only specified for claimed power dissipation at
minus 100C!

Care to point to a datasheet that shows that?

http://www.resistorsonline.com/wire-wound-resistor.html

Thats saying nothing like that. Look at the table at the bottom, stupid.
Its saying that the are specified for claimed power dissipation at 70C