On Sun, 19 Aug 2007 08:34:27 -0700 someone who may be
wrote this:-

If you leave a filament bulb on, it will generally last much longer
than if you turn it on and off.

Do you have further information on this? I understood that avoidance
of switch-on surges gave only minimal extra life to GLS lamps, though
considerable extra life to halogens.

It is the same with valves. Left on they can last for a very long
time, turned on and off they can be unreliable. See Tommy Flowers,
1930s telecommunications equipment and the genesis of Colossus for
the evidence.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 19 Aug 2007 12:55:17 -0400 someone who may be willshak
wrote this:-

I've had the spiral CFL bulbs installed in all of my formerly
incandescent bulb lamps, wherever the lamp took a regular bulb. The
exceptions are mini spots,

There are now some good energy saving bulbs for these.

and decorative candelabra bulbs.

While there is no equivalent of clear bulbs there are now a number
of "candle" shaped energy saving bulbs that are very similar to
pearl "candle" bulbs.

It is becoming difficult to find an indoor application where there
is not a suitable energy saving bulb.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

In article , Mike Ruskai wrote:
On or about Sun, 19 Aug 2007 04:07:06 -0400 did mm
dribble thusly:

On Sat, 18 Aug 2007 10:40:33 -0700, wrote:

I have understood that switching fluorescent lamps - tubes - on and
off was not a good idea and that they should be switched on and left
on. Unlike filament lamps which do not seem to mind.

Why do you say they don't mind? Haven't you noticed that they almost
always burn out at the moment they are turned on?

I was amazed no one had pointed out the error in that statement, and
was about to comment. Sure enough, last message in the thread, and
I'm scooped.

Most incandescents do not suffer significant wear from starting. What
happens is that an aging filament becomes unable to survive a cold start a
little before it becomes unable to survive continuous operation.

An incandescent burnout is generally from melting of a thiner hotter
section of the filament. Such a "thin spot" has a temperature overshoot
during a cold start.

Once a filament has a hot-running thin spot that becaomes unable to
survive a cold start, its hours are numbered. The thin spot suffers worse
evaporation because it runs hotter, and this condition accelerates worse
than exponentially, so the filament's days/hours are numbered once it is
in bad enough shape to be unable to survive a cold start.

- Don Klipstein )

In article , John Rumm wrote:
wrote:

This whole subject is filled with myth and bad advice. Today for
domestic installs, the only sensible thing to do is turn off when not
wanted, however long or short that may be.

Unless you have one of those pesky CFLs that take 10 mins to achieve a
worthwhile light output! ;-)

I see few taking that long, and they tend to be outdoor types in colder
conditions.

If you want ones that warm up faster, I have found in general that ones
without outer bulbs start brighter and warm up faster than ones with outer
bulbs. Ones with outer bulbs have the tubing getting hotter, and are
designed to work optimally at such a higher tubing temperature.

- Don Klipstein )

On Aug 19, 10:35 am, Smitty Two wrote:
In article .com,





wrote:
On Aug 19, 3:03 am, mm wrote:
On Sun, 19 Aug 2007 02:54:32 +0100, John Rumm

wrote:
Fred wrote:

It's very much the issue! I recall stories as the poster had where the
starting of a fluorescent tube was equivalent to 1/2 hour running.

Analyse that statement logically and you will see it makes no sense....

First off, it's true, and it may be the basis for the original post,
so it's worth discussing.

Secondly, I would say that it does make sense**, but it's not accurate
and for someone who knows anything about the topic, it's not
believable.

Something that makes no sense, to me, would be something whose
intended meaning I can't discern.

**A lot of things use more electricity on start-up, so the sentence is
not illogical. But the numbers are wrong.

Well, Duh! His obvious point was that if you look at the real facts,
which he clearly presented, then it makes no sense, because the
current required in the few secs of startup would be huge. And I
think your definition of "makes no sense" equals "can't discern
intended meaning" isn't exactly mainstream. For example, if someone
said that Mars revolves aroung the Earth, the meaning is quite clear,
yet any reasonable person would say that makes no sense.

mm's definition may not be mainstream, but it's correct.

According to whom? Here's a dictionary definition of the word sense,
when used as a noun:

The American Heritage® Dictionary of the English Language: Fourth
Edition. 2000

"sense 4c. Something sound or reasonable: There's no sense in waiting
three hours."

Or applied in this case:

Analyse that statement logically and you will see it makes no sense...

or my example:

For example, if someone said that Mars revolves aroung the Earth, the meaning is quite clear, yet any reasonable person would say that makes no sense.


Both of those are perfectly correct usage as defined by the
dictionary, not colloquialisms or misuse of the English language. So
maybe you should check the dictionary before you start spouting about
collective ignorance.


Colloquialisms
aside, the liberties we take with our (mis-)use of the English language
are staggering. It's surprising we understand half of what's said or
written. I try to bite my tongue when it comes to playing grammar and
spelling cop on usenet, (and I'm not even close to perfect myself, and
well aware of it) but there's a hell of a lot of people wandering around
the planet that barely qualify as literate. The significance and
implications of our collective ignorance are widely underestimated.- Hide quoted text -

- Show quoted text -

In article , Alan wrote:

I've just had a Pro-life 25W spiral bulb fail in a spectacular way (very
loud bang followed by lingering burnt smell). It's been fitted
approximately 6 months.

I avoid 25 watt spirals, especially of brands that are neither "Big 3"
nor home center mainstays.

It appears to me that a big run of bad 25 watt spirals was made around
2000-2001 or so. I bought one of the Lights of America brand (and that
brand I often had trouble with) and 2 of the GE brand (GE is one of the
"Big 3" and normally does well). All 3 burned out in only a few hundred
operating hours, but quietly.

I have seen only a year or two ago 25 watt spirals at Walgreens, of a
brand that I cannot remember, that appeared to me to be of similar
vintage. So I am suspicious that there are businesses that bought some of
that boatload of 2000-2001 or whatever garbage and hope to make money
reselling it under different brands.

========================

As for CFLs failing with a bang: Sadly, that was somewhat normal.

Two ways for a CFL to make a loud pop and what the manufacturers have
done about it (or should be doing):

1. A usual screw base CFL with internal electronic ballast has a filter
capacitor after the rectifier. This capacitor has limited life
expectancy, especialy at elevated temperatures. It also contains a water
solution of electrolyte, since it is an electrlytic capacitor.

If this capacitor gets too hot, the electrolyte can boil and make the
capacitor burst. The capacitor's housing is normally designed to break
without producing shrapnel of the housing.

A few years ago, quite a few people were disturbed by CFLs going POW and
occaisionally dripping electrolyte. Usually, at least one of the
following is usually the case:

* The CFL was an off-brand one
* The CFL was operated in a higher temperature environment than the
manufacturer anticipated, often in a downlight or a small enclosed
fixture
* The capacitor was not as good as the CFL manufacturer thought

What manufacturers have done about this: They have gotten better at
using capacitors that are up to the task of CFL duty.
I'm sure there will still be some capacitors popping in the future, but
I am already hearing less about capacitors popping than I heard earlier
this decade.

2. The electronic ballast shorts and a wire or a part acts as a fuse,
sometimes with a loud pop or bang. Sometimes part of the ballast gets
scorched or discolored by smoke.

If the CFL is UL listed and production units conform to units tested by
UL, then the ballast and ballast housing materials are sufficiently flame
retardant for the CFL to be reasonably safe from starting a fire.

However, I hope the manufacturers are aware that a light bulb going out
with a bang, smoke output or getting a visible scorch mark in the process
appears scary and does not make good press. I would hope they now put in
fuses to make semiconductor failures/malfunctions leading to the CFL dying
less spectacularly.

I expect less scary failures from manufacturers that hope to still be in
the CFL business 10 years from now. I think "Big 3" (Philips, GE,
Sylvania) would want to avoid bad press, so I think they mostly make
better CFLs.

- Don Klipstein )

In article .com,
wrote:
Don Klipstein wrote:

Don is a lighting expert with a very informative and detailed site
last time I looked. However readers should bear in mind that tube
types, starting types, costs, common practices and terminology are all
different here in UK to the US.

Also I think somehting was missed in your calculations of switch off
break even time. If keeping the tube on for 20 minutes gains you 20
minutes extra tube life, you have in fact gained absolutely nothing.
The only difference is that 20 minutes of electricity have been
wasted. You wont get a single extra day of service time out of the
tube this way. I dont know why but this is so often overlooked in
these calculations.

Oops, I was only calculating break-even points in whether cost of
operating the lamp is increased or decreased, without regard to
considering leaving-the-lamp-on causes some of the lamp's life to be
wasted in addition to the electricity being wasted.

I expect that adding consideration of wasting lamp operating life will
change break-even-time calculations and make break-even times shorter.

I expect this correction will only make break-even times slightly
shorter if electricity consumption during the life of the lamp (bulb)
costs a lot more than the lamp (bulb) does, which is often the case.
With lower wattage lamps, lamp cost becomes a more significant fraction
of the total cost, so this correction gets less minor.

- Don Klipstein )

In article , Grimly
Curmudgeon wrote:
We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember saying something
like:

Do you have further information on this? I understood that avoidance
of switch-on surges gave only minimal extra life to GLS lamps, though
considerable extra life to halogens.

As anecdotal evidence only...
I've noticed (as have others) that side-mounted filament lamps don't
last long, typically a few months of normal useage. Since powering a
desktop lamp through a push-button dimmer and using that dimmer as the
only on/off switch the same bulb has been in that lamp for the past 4
years. Ordinary 60W bulb, btw.

Many dimmers don't let you achieve full brightness. The bulb may
randomly have longer-than-average life. Some "ordinary" bulbs are
long-life versions (with slightly less light output).

So I am not surprised.

- Don Klipstein )

Many thanks for all your informative and illuminating inputs - the way
ahead is much brighter now. I amazed that this thread has not
degenerated into the usual flaming after a few posts - I can only
assume that a better class of person inhabits the a.h.r and uk.diy
threads. Best regards.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember John Rumm
saying something like:

I also expect that is is a corruption of the original research that was
looking at overall costs including lamp life and not just running costs.
It has just that much of the detail has been lost in the Chinese
whispers along the way and it has been reduced to an absurdity
concerning just energy costs.

Ding!

The first time I read about this was nearly 30 years ago in New
Scientist, where the article made the point it was about overall
lifetime of the lamp and fittings, rather than electricity consumption.
In that original article there was bare mention at all of the start-up
energy cost, probably because it was insignificant. The piece
illustrated how the lifetime of a lamp was reduced by multiple starts,
and showed that it was more economical *at that time* to reduce the
number of starts, or once started, leave the lamp on for a while.

At that time, with the fluorescent lamps and fittings available and the
energy cost of the day, the break-even point was 20 minutes.

It's usenet, so it's not unknown for the ill-informed start an argument
without knowing the full story.
--

Dave

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember (Don Klipstein)
saying something like:


Many dimmers don't let you achieve full brightness. The bulb may
randomly have longer-than-average life. Some "ordinary" bulbs are
long-life versions (with slightly less light output).

So I am not surprised.

Good for you. Have a coconut.
--

Dave

In article ,
"** Frank **" writes:

Not good for filament lamps too. In fact, too many switching operations are

Actually, regular mains filament lamps don't care about switching,
and it doesn't shorten their lives. (This might not apply to high
current and halogen lamps, for which I haven't seen figures.)

not good for most things like computers, motors, TVs, etc. Switching
transients (both switching on and off) could have many thousand volts and
could draw 10x or more rated current across the device which could results
in electrical, mechanical and thermo shock. Note many lamp failures are at
the moment of switching either on or off.

That's why people think that switching shortens their life, but
it's a misunderstanding of what's happening. At the end of life,
lamps can continue operating for a few hours past the point where
they won't survive another switch-on. If you switch them off
during this period, they will blow at next switch-on, and in the
case of a lamp which isn't normally switched on for an hour or
more, it's pretty certain to blow at a switchon rather than whilst
running. However, this is independant of the number of times the
lamp has been switched on in the past and depends only on burning
hours. There are a number of applications where this effect can be
measured, such as continuously flashing signs which use regular
lamps, where life can be seen to depend on total burning hours
and not frequency of switching.

My own experience is CFLs (and Circle Lines) are much more susceptible to
switching than incandescent or the 4' and 8' fluorescent lamps. YMMV.

Assuming the most common fluorescent tube failure mode (electrode
emission mix all sputtered off), it depends on the design of the
control gear, and not much on the type of tube.

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

David Hansen wrote:
On Sun, 19 Aug 2007 08:34:27 -0700 someone who may be
wrote this:-

If you leave a filament bulb on, it will generally last much longer
than if you turn it on and off.

Do you have further information on this? I understood that avoidance
of switch-on surges gave only minimal extra life to GLS lamps, though
considerable extra life to halogens.

It is the same with valves. Left on they can last for a very long
time, turned on and off they can be unreliable. See Tommy Flowers,
1930s telecommunications equipment and the genesis of Colossus for
the evidence.

But the 2 situations arent comparable afaics. Filament failure vs
oxdide contamination on a filament heater running only red hot.


NT

wrote:

Many thanks for all your informative and illuminating inputs - the way
ahead is much brighter now. I amazed that this thread has not
degenerated into the usual flaming after a few posts - I can only
assume that a better class of person inhabits the a.h.r and uk.diy
threads. Best regards.

Perhaps if we'd been discussing gas lamps it might have done...


NT

David Hansen wrote:
On Sun, 19 Aug 2007 12:55:17 -0400 someone who may be willshak
wrote this:-

I've had the spiral CFL bulbs installed in all of my formerly
incandescent bulb lamps, wherever the lamp took a regular bulb. The
exceptions are mini spots,

There are now some good energy saving bulbs for these.

and decorative candelabra bulbs.

While there is no equivalent of clear bulbs there are now a number
of "candle" shaped energy saving bulbs that are very similar to
pearl "candle" bulbs.

It is becoming difficult to find an indoor application where there
is not a suitable energy saving bulb.

CFL candle lamps will fit chandeliers etc, but imho they dont come
anywhere near being a replacement in visual terms. The appearance is
bulkier, ungainly, and they have no sparkle at all, unlike clear
filament candles. Also with chandeliers the splitting of colours
depends on a small light source, so use of CFLs does this no favours
either. Chandeliers are one app where filaments still rule. LV
filaments can at least gain a bit more efficiency over mains.


NT

Don Klipstein wrote:
In article .com,
wrote:

I expect that adding consideration of wasting lamp operating life will
change break-even-time calculations and make break-even times shorter.

I expect this correction will only make break-even times slightly
shorter if electricity consumption during the life of the lamp (bulb)
costs a lot more than the lamp (bulb) does, which is often the case.
With lower wattage lamps, lamp cost becomes a more significant fraction
of the total cost, so this correction gets less minor.

- Don Klipstein )

I would think it would make quite a big difference, but havent calced
it yet.


NT

"mm" wrote in message
...
On Sun, 19 Aug 2007 02:54:32 +0100, John Rumm
wrote:

Fred wrote:

It's very much the issue! I recall stories as the poster had where the
starting of a fluorescent tube was equivalent to 1/2 hour running.

Analyse that statement logically and you will see it makes no sense...

First off, it's true, and it may be the basis for the original post,
so it's worth discussing.

Secondly, I would say that it does make sense**, but it's not accurate
and for someone who knows anything about the topic, it's not
believable.


Many thanks for your support. I was trying to make the point, admittedly
badly, that in the 70's that there was the misapprehension that starting a
fluorescent tube took an inordinate amount of energy. I think we both agree
that this is very untrue.

On Sat, 18 Aug 2007 22:56:48 +0100, Derek Geldard
wrote:

:Nowadays domestic users of fluorescent tubes need not concern
:themselves too much, but "Best Practice" is "Best Practice". If you
:have a fitting that requires a lot of effort to get at (above the
:stairs say) it makes sense to get the most out of the tube.
:
G

Yes, DG has it right. The issue is NOT energy usage here but the life of
the bulb. Turning a CF on and off a lot DOES shorten the life. It may
have 10,000 hours MTBF, say, but if you turn it on and off 10,000 times
the life isn't apt to be 10,000 hours! I don't know if the bulbs have
gotten better that way, but what HAS been getting better is the cost of
the bulbs. They still aren't nearly as cheap as incandescents, but the
economy of the situation has incandescents out of the picture. I haven't
bought one in quite a few years.

If I only need a CF on for a few seconds, in my workroom, say, I
generally use a flashlight rather than turn on the overhead light for
10-15 seconds in order to find what I need. At the ceiling are two CF's,
and I don't want to wear them out. I've heard that nowadays the life is
only shortened maybe 5 minutes, but I suspect that's quite inaccurate. I
have had several CF's fail way before they were supposed to. There's a
circular one in my kitchen that would probably cost me over $10 to
place, and the one it replaced lasted maybe 10-15% of the supposed life
expectancy.

Dan

On Sun, 19 Aug 2007 00:40:40 +0000 (UTC), (Don
Klipstein) wrote:

:"Program Start" - this is used in some CFLs. The bulb does not come on
:at all until a fraction of a second to about a second after power is
:applied, then turns on without blinking. It may have a "rapid fade-on"
:during a fraction of a second.
: This causes the least wear, and is often used in CFLs of Philips and
:Sylvania brands (and some others but I can't remember who and I have not
:tried them all).

Yes, IIRC Philips and Sylvania are among the handful of brands that I
have seen recommended, and consequently I have bought several. I have
had very spotty luck with off-brand CFL's lasting anything near the
advertized MTBF. In recent years I have seen some pretty good deals on
CFL's and bought some off brands anyway.

Dan

In article , Dan_Musicant wrote:
On Sat, 18 Aug 2007 22:56:48 +0100, Derek Geldard
wrote:

:Nowadays domestic users of fluorescent tubes need not concern
:themselves too much, but "Best Practice" is "Best Practice". If you
:have a fitting that requires a lot of effort to get at (above the
:stairs say) it makes sense to get the most out of the tube.
:
G

Yes, DG has it right. The issue is NOT energy usage here but the life of
the bulb. Turning a CF on and off a lot DOES shorten the life. It may
have 10,000 hours MTBF, say, but if you turn it on and off 10,000 times
the life isn't apt to be 10,000 hours! I don't know if the bulbs have
gotten better that way, but what HAS been getting better is the cost of
the bulbs. They still aren't nearly as cheap as incandescents, but the
economy of the situation has incandescents out of the picture. I haven't
bought one in quite a few years.

If I only need a CF on for a few seconds, in my workroom, say, I
generally use a flashlight rather than turn on the overhead light for
10-15 seconds in order to find what I need. At the ceiling are two CF's,
and I don't want to wear them out. I've heard that nowadays the life is
only shortened maybe 5 minutes, but I suspect that's quite inaccurate. I
have had several CF's fail way before they were supposed to. There's a
circular one in my kitchen that would probably cost me over $10 to
place, and the one it replaced lasted maybe 10-15% of the supposed life
expectancy.

My suspicions:

1. Heat - see if it gets unduly warm where that light is. Rated life is
with ambient temperature 25 degrees C (77 degrees F).
Better ones should have only slight incidence of early failures if it
gets a fair amount warmer. But if you have an enclodure around it, try
removing the enclosure.

2. Was it a brand other than GE, Sylvania or Philips? Most "circline"
lamps that I have seen to go into screw sockets have been by Lights of
America so far, and I have had a disproportionate share of LOAs die young.
(However, I have only bought one LOA since 2001 so they may have
improved.) I have also generally experienced LOAs (as well as Maxlites)
to be a little dimmer than others of same claimed light output.

- Don Klipstein )

On Mon, 20 Aug 2007 11:38:55 -0700 someone who may be
wrote this:-

Do you have further information on this? I understood that avoidance
of switch-on surges gave only minimal extra life to GLS lamps, though
considerable extra life to halogens.

It is the same with valves. Left on they can last for a very long
time, turned on and off they can be unreliable. See Tommy Flowers,
1930s telecommunications equipment and the genesis of Colossus for
the evidence.

But the 2 situations arent comparable afaics. Filament failure vs
oxdide contamination on a filament heater running only red hot.

The comparison is one of whether leaving on equipment involving hot
bits of metal has advantages in terms of reliability. It does in
many fields, but this has to be weighed against the energy
consumption of doing so.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54