In article ,
Martin Brown wrote:
On 08/07/2013 17:46, Mike Barnes wrote:
Martin Brown :
0.12p/kW hr

Blimey, that's cheap.

Good old Scottich Electricity! There is a standing charge as well and
any use over a certain base amount is 20p/kWhr or something like that.

As we have oil fired CH and solid fuel the electricity usage generally
stays well inside their lower tariff band except in cold winters.

Anyway if your electricity is more expensive then it strengthens the
case for using the most efficient possible lights in 24/7 applications.

They were already a winner on my very conservative assumptions.

Comparing electricity prices is a PITA all the online comparison sites
want way too much detail from you before they will allow you to see any
of the numbers! Confusing electricity tariff #2456 (T&C apply) is only
available to one legged pirates with a parrot on the left shoulder etc.

If I could get electricity at 0.12p per unit I'd not be much worried about
usage.

--
*Stable Relationships Are For Horses. *

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

Martin Brown :
On 08/07/2013 17:46, Mike Barnes wrote:
Martin Brown :
0.12p/kW hr

Blimey, that's cheap.

Good old Scottich Electricity! There is a standing charge as well and
any use over a certain base amount is 20p/kWhr or something like that.

[Whoosh!]

ITYM £0.12 or 12p.

--
Mike Barnes

On 09/07/2013 11:18, Mike Barnes wrote:
Martin Brown :
On 08/07/2013 17:46, Mike Barnes wrote:
Martin Brown :
0.12p/kW hr

Blimey, that's cheap.

Good old Scottich Electricity! There is a standing charge as well and
any use over a certain base amount is 20p/kWhr or something like that.

[Whoosh!]

ITYM £0.12 or 12p.

Ooops!!! What's an order of magnitude or two between friends?

--
Regards,
Martin Brown

On Monday, 8 July 2013 14:58:30 UTC+1, Martin Brown wrote:
On 08/07/2013 14:04, whisky-dave wrote:

On Monday, 8 July 2013 09:47:13 UTC+1, Martin Brown wrote:

On 04/07/2013 22:41, Dave Liquorice wrote:





http://www.amazon.co.uk/Philips-Visi...pd_sim_light_8



"this equates to about 25 years if used for a few hours per day."



So in the real world pretty useless I'd say, for me anyway.



How do you arrive at that conclusion?

Because if I'm to save money the bulbs have to be onb a significant amoubt of time. If you leave LEDS on for that long their life shortens quite quickily.


"Long life 25000 hour or ten year lifespan in normal use means they last much longer than ordinary bulbs, this equates to about 25 years if used for a few hours per day."

I've had LEDS go in under 3 years. I want their estimate of the LEDs life if they were on 6-8 hours per day.





The corresponding numbers for each technology and a nominal 60W bulb

operated 24/7 based on manufacturers claimed MTBF are as follows:

NOT for LEDS their life times are quoted for 4 hours per day or less.


Type Bulb Electricity/year Lifetime

LED 10W £10 £11 50,000 hrs ? (unproven)

CFL 12W £4 £13 8,000 hrs

Halogen 42W £3 £46 2,000 hrs

Basic 60W £0.5 £69 1,000 hrs (pessimistic)



Working on 0.12p/kW hr and ~9000hrs/year a 10W continuous load costs

about £11 to run. One reason why reducing your home base load is good....



The corresponding costs to operate for 100,000 hours are therefore

(number of lamps used) - ignores any installation costs



LED (2) £20 + £121 = £141

CFL (11) £44 + £141 = £185

Hal (50) £150 + £506 = £656

Bas (100) £50 + £759 = £809



In actual fact traditional filament bulbs will probably last a fair bit

longer when left on continuously than makers normal use MTBF and solid

state electronics may expire sooner.

Yes much sooner.



But the message is clear: If you

can afford the up front costs of new high efficiency bulbs then you will

win from the second year onwards even replacing CFLs with LED.

Every year or so we get new higher efficiency bulbs.


On worst case assumptions that solid state LED designs are only twice as

reliable as the old CFLs rather than 6x longer lasting the LED lamp

still wins out (just). The traditional bulbs might be dirt cheap but

they are inefficient and waste a lot of their input power as heat.

LEDs also waste energy in heat, but that heat never goes anywhere useful all it does it heat up the materail and reduces the LEDS life span.


If you have mains spikes then filament bulbs tend to blow and our old

kitchen spotlamps tended to take the main lighting circuit down too.

Well I don't so it's not really a problem.


I view all manufacturers MTBF claims with a big pinch of salt because I

know first hand what slimy marketeers can do to real engineering data.

Yep.
I've brought 4 LEDs tubes, be intersting to see how they do.

On 09/07/2013 13:49, whisky-dave wrote:
On Monday, 8 July 2013 14:58:30 UTC+1, Martin Brown wrote:
On 08/07/2013 14:04, whisky-dave wrote:

On Monday, 8 July 2013 09:47:13 UTC+1, Martin Brown wrote:

On 04/07/2013 22:41, Dave Liquorice wrote:

http://www.amazon.co.uk/Philips-Visi...pd_sim_light_8

"this equates to about 25 years if used for a few hours per day."

So in the real world pretty useless I'd say, for me anyway.

How do you arrive at that conclusion?

Because if I'm to save money the bulbs have to be onb a significant amoubt of time. If you leave LEDS on for that long their life shortens quite quickily.
"Long life 25000 hour or ten year lifespan in normal use means they last much longer than ordinary bulbs, this equates to about 25 years if used for a few hours per day."

I've had LEDS go in under 3 years. I want their estimate of the LEDs life if they were on 6-8 hours per day.

I have yet to see an LED fail of old age and I have some original ones
from the early 70s. The main way that they fail is though abuse when
bending the legs or inadequate heatsinking on the new high power LEDs.

3 years is about the maximum life of the current CFLs. High power
production LED lamps haven't been around long enough for you to have had
one fail with three years of use unless you are an incredibly early
adopter with money to burn or an insider at a research lab.

The LED lamps available three years ago were *very* expensive eg

http://www.cree.com/news-and-events/...818-home-depot

"under $50" which ISTR meant $49.99

The corresponding numbers for each technology and a nominal 60W bulb
operated 24/7 based on manufacturers claimed MTBF are as follows:

NOT for LEDS their life times are quoted for 4 hours per day or less.

Rubbish. I can believe that the lifetime of the control electronics will
be limited a bit by continuous usage but the LED reaches thermal
equilibrium very quickly after being switched on. The capacitors will
dry out slightly faster when warm but in a good design they are well
within limits. I don't doubt there are some bad ones out there too.

Type Bulb Electricity/year Lifetime

LED 10W £10 £11 50,000 hrs ? (unproven)

CFL 12W £4 £13 8,000 hrs

Halogen 42W £3 £46 2,000 hrs

Basic 60W £0.5 £69 1,000 hrs (pessimistic)



Working on 0.12p/kW hr and ~9000hrs/year a 10W continuous load costs
about £11 to run. One reason why reducing your home base load is good...



The corresponding costs to operate for 100,000 hours are therefore

(number of lamps used) - ignores any installation costs



LED (2) £20 + £121 = £141

CFL (11) £44 + £141 = £185

Hal (50) £150 + £506 = £656

Bas (100) £50 + £759 = £809



In actual fact traditional filament bulbs will probably last a fair bit
longer when left on continuously than makers normal use MTBF and solid
state electronics may expire sooner.

Yes much sooner.

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.



But the message is clear: If you
can afford the up front costs of new high efficiency bulbs then you will
win from the second year onwards even replacing CFLs with LED.

Every year or so we get new higher efficiency bulbs.

Yes. But if you buy an LED now instead of a CFL you will be ahead after
under two years including the electricity used - and the savings are
even better if you are not on an optimum low use tariff.


On worst case assumptions that solid state LED designs are only twice as
reliable as the old CFLs rather than 6x longer lasting the LED lamp
still wins out (just). The traditional bulbs might be dirt cheap but
they are inefficient and waste a lot of their input power as heat.

LEDs also waste energy in heat, but that heat never goes anywhere useful all it does it heat up the materail and reduces the LEDS life span.

The amount of waste heat from LEDs is usually too small to notice. It is
only a problem in a very confined insulated space with no airflow. The
sort of position that halogen downlighters tend to be installed in.

Putting LEDs into such an environment ensures near certain early death,
but that doesn't stop people selling them to consumers.

If you have mains spikes then filament bulbs tend to blow and our old
kitchen spotlamps tended to take the main lighting circuit down too.

Well I don't so it's not really a problem.

It affects plenty of people who do see local mains spikes.

I've brought 4 LEDs tubes, be intersting to see how they do.

So far so good is my experience.


--
Regards,
Martin Brown

On Tue, 09 Jul 2013 14:40:24 +0100, Martin Brown wrote:

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Ah, hold on whilst I just rummage around for the GU10ish-form-factor LED
bulb that I've just lobbed.

I don't know how old it is/was, but of the 7 or 8 individual LEDs within
it, only two were still working. "Megaman" brand.

On 09/07/2013 15:08, Adrian wrote:
On Tue, 09 Jul 2013 14:40:24 +0100, Martin Brown wrote:

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Ah, hold on whilst I just rummage around for the GU10ish-form-factor LED
bulb that I've just lobbed.

I don't know how old it is/was, but of the 7 or 8 individual LEDs within
it, only two were still working. "Megaman" brand.

That would be the sort that you put in a position designed for a halogen
lamp. I have already said that they will expire quickly!

I am only considering well engineered units in sensible free air or
fixtures designed with LED heatsinking requirements in mind.

--
Regards,
Martin Brown

On Mon, 8 Jul 2013 06:04:21 -0700 (PDT), whisky-dave wrote:

http://www.amazon.co.uk/Philips-Visi...rd-Instant/dp/
B0083WDMPW/ref=pd_sim_light_8

"this equates to about 25 years if used for a few hours per day."

So in the real world pretty useless I'd say, for me anyway.

Not to mention:

"Philips state they are euivalnet to a 25w bulb but they give off 250
Lumens which other manufacturers compare to a"

To a watt?

But again only 250 lm, just a tad more than 1/3 of a 60W tungsten.

At least it looks like it might have better light distribution.

--
Cheers
Dave.

On Tue, 09 Jul 2013 08:12:42 +0100, Martin Brown wrote:

Comparing electricity prices is a PITA all the online comparison sites
want way too much detail from you before they will allow you to see any
of the numbers!

Like what, to give meaningful results they need to know where in the
country you are, who your current supplier is and the current tariff
name and a fairly accurate annual usage.

But yes, getting the real figures to plug into your own spreadsheet
can be a PITA but it's normally easier on a comparison site than the
direct with the supplier. They quite often have a single 60 page .pdf
with electricity only, duel fuel, gas only with every tariff for each
of those and all the variations that arise from the 16 electricity
regions. The comparison sites at least filter all that irrelevant
information quite well.

--
Cheers
Dave.

On Tue, 09 Jul 2013 15:50:15 +0100, Martin Brown wrote:

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Ah, hold on whilst I just rummage around for the GU10ish-form-factor
LED bulb that I've just lobbed.

I don't know how old it is/was, but of the 7 or 8 individual LEDs
within it, only two were still working. "Megaman" brand.

That would be the sort that you put in a position designed for a halogen
lamp. I have already said that they will expire quickly!

I am only considering well engineered units in sensible free air or
fixtures designed with LED heatsinking requirements in mind.

That's a bit of a cop-out, Martin.

A 50w Halogen bulb emits MUCH, MUCH more heat than those LEDs. There
ain't no way that an LED designed to be a replacement for a halogen is
going to expire because of heat, unless the actual LED "bulb" itself is
designed incredibly badly. It certainly isn't going to be due to lack of
heatsinking or free air of the actual fitting, unless using a halogen
would have resulted in a minor conflagration (or molten plastic, at the
very least) in minutes flat.

Hell, the last LED GU10-fitment bulbs I bought were for sunken, sealed
light fittings - and those fittings specifically _demanded_ LEDs
precisely because of the lack of free air.

(and, yes, those were replacements for failed LEDs, too - but that was
due to water ingress)

On 09/07/2013 16:20, Adrian wrote:
On Tue, 09 Jul 2013 15:50:15 +0100, Martin Brown wrote:

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Ah, hold on whilst I just rummage around for the GU10ish-form-factor
LED bulb that I've just lobbed.

I don't know how old it is/was, but of the 7 or 8 individual LEDs
within it, only two were still working. "Megaman" brand.

That would be the sort that you put in a position designed for a halogen
lamp. I have already said that they will expire quickly!

I am only considering well engineered units in sensible free air or
fixtures designed with LED heatsinking requirements in mind.

That's a bit of a cop-out, Martin.

Not really.
I don't count failures due to badly engineered retrofit designs.

A 50w Halogen bulb emits MUCH, MUCH more heat than those LEDs. There

And the enclosure and insulation around it is designed to protect the
rest of the building from the insanely hot halogen lamp envelope.

ain't no way that an LED designed to be a replacement for a halogen is
going to expire because of heat, unless the actual LED "bulb" itself is
designed incredibly badly. It certainly isn't going to be due to lack of
heatsinking or free air of the actual fitting, unless using a halogen
would have resulted in a minor conflagration (or molten plastic, at the
very least) in minutes flat.

A halogen lamp or any filament lamp can survive happily with ambient
temperatures that will melt plastics so long as it doesn't get so hot
that it softens the glass seal. By comparison the capacitors in a CFL or
LED controller will die after not that long held at 100C or above and
suffer a shorter life with above ambient operating temperature.

That is why LED/CFL in glass globes and designed for halogen lamp
downlighters tend to end up dead pretty quickly.

It would be interesting to put an irreversible thermometer telltale on
one of your dying LED units to see how hot they really get. This would
be too dangerous to do with a halogen lamp as it might well catch fire!

My money is on something around 70-90C after a couple of hours.

Hell, the last LED GU10-fitment bulbs I bought were for sunken, sealed
light fittings - and those fittings specifically _demanded_ LEDs
precisely because of the lack of free air.

(and, yes, those were replacements for failed LEDs, too - but that was
due to water ingress)

Some are definitely more equal than others. FWIW I am inclined to agree
with you that GU10 LED units are mostly a waste of money - not fit for
purpose. YMMV (although in this case it clearly doesn't)

--
Regards,
Martin Brown

On Tuesday, 9 July 2013 14:40:24 UTC+1, Martin Brown wrote:
On 09/07/2013 13:49, whisky-dave wrote:

On Monday, 8 July 2013 14:58:30 UTC+1, Martin Brown wrote:

On 08/07/2013 14:04, whisky-dave wrote:



On Monday, 8 July 2013 09:47:13 UTC+1, Martin Brown wrote:



On 04/07/2013 22:41, Dave Liquorice wrote:



http://www.amazon.co.uk/Philips-Visi...pd_sim_light_8



"this equates to about 25 years if used for a few hours per day."



So in the real world pretty useless I'd say, for me anyway.



How do you arrive at that conclusion?



Because if I'm to save money the bulbs have to be onb a significant amoubt of time. If you leave LEDS on for that long their life shortens quite quickily.

"Long life 25000 hour or ten year lifespan in normal use means they last much longer than ordinary bulbs, this equates to about 25 years if used for a few hours per day."



I've had LEDS go in under 3 years. I want their estimate of the LEDs life if they were on 6-8 hours per day.



I have yet to see an LED fail of old age and I have some original ones

from the early 70s.

They must be very original then, there were few about in the early 70s and non were meant for mains lighting.
In 1978/9 blue LEDS were about £30 each.

The main way that they fail is though abuse when

bending the legs or inadequate heatsinking on the new high power LEDs.

inadequate heatsinking, yes perhaps that's it, as I said.
If the heatsinking were adequate they could be left on longer.


3 years is about the maximum life of the current CFLs. High power

production LED lamps haven't been around long enough for you to have had

one fail with three years of use unless you are an incredibly early

adopter with money to burn or an insider at a research lab.


Makes you wonder how they work out they'll last 25 years doesn't it.

Mine weren't the high power production LEDs.


The corresponding numbers for each technology and a nominal 60W bulb

operated 24/7 based on manufacturers claimed MTBF are as follows:



NOT for LEDS their life times are quoted for 4 hours per day or less.



Rubbish. I can believe that the lifetime of the control electronics will

be limited a bit by continuous usage but the LED reaches thermal

equilibrium

So what we're talking abouyt what you buy not individual parts.

If the control circurty fails how much will it cost to replace it.

your not one of these crackpots selling this crap on ebay are you.
A friend opf mione spent quite a bit on such LEDS shipped from china 20% failed in under a month, mosty likely fakes.





very quickly after being switched on. The capacitors will

dry out slightly faster when warm but in a good design they are well

within limits. I don't doubt there are some bad ones out there too.

In those you have quoted, why only quote for them if left on for a few hours a day ?


In actual fact traditional filament bulbs will probably last a fair bit

longer when left on continuously than makers normal use MTBF and solid

state electronics may expire sooner.



Yes much sooner.



The jury is still out on that one. I haven't owned any for long enough

to see a single LED unit failure yet. CFLs on the other hand expire

after ~3 years in normal use due to tube failure or capacitor

degradation and I have enough to be pretty sure of the statistics.

Me too, I won't be buying them just yet. I'll wait for the real users results.





Every year or so we get new higher efficiency bulbs.



Yes. But if you buy an LED now instead of a CFL you will be ahead after

under two years including the electricity used - and the savings are

even better if you are not on an optimum low use tariff.

Depends on the use, I have little use for LEDs bulbs in the home
as for efficint lighting.



LEDs also waste energy in heat, but that heat never goes anywhere useful all it does it heat up the materail and reduces the LEDS life span.



The amount of waste heat from LEDs is usually too small to notice. It is

only a problem in a very confined insulated space with no airflow. The

sort of position that halogen downlighters tend to be installed in.

Never had them never wanted them sio no need to replace them.


Putting LEDs into such an environment ensures near certain early death,

but that doesn't stop people selling them to consumers.


Never had them never wanted them sio no need to replace them.




I've brought 4 LEDs tubes, be intersting to see how they do.



So far so good is my experience.

Haven't installed them yet.


Regards,

Martin Brown

On 09/07/2013 17:10, whisky-dave wrote:
On Tuesday, 9 July 2013 14:40:24 UTC+1, Martin Brown wrote:
On 09/07/2013 13:49, whisky-dave wrote:

On Monday, 8 July 2013 14:58:30 UTC+1, Martin Brown wrote:

On 08/07/2013 14:04, whisky-dave wrote:

On Monday, 8 July 2013 09:47:13 UTC+1, Martin Brown wrote:

On 04/07/2013 22:41, Dave Liquorice wrote:

http://www.amazon.co.uk/Philips-Visi...pd_sim_light_8

"this equates to about 25 years if used for a few hours per day."

So in the real world pretty useless I'd say, for me anyway.

How do you arrive at that conclusion?

Because if I'm to save money the bulbs have to be onb a significant amoubt of time. If you leave LEDS on for that long their life shortens quite quickily.

"Long life 25000 hour or ten year lifespan in normal use means they last much longer than ordinary bulbs, this equates to about 25 years if used for a few hours per day."

I've had LEDS go in under 3 years. I want their estimate of the LEDs life if they were on 6-8 hours per day.

I have yet to see an LED fail of old age and I have some original ones
from the early 70s.

They must be very original then, there were few about in the early 70s and non were meant for mains lighting.
In 1978/9 blue LEDS were about £30 each.

They are original red, yellow and green (the green isn't good at all)
from about 1974. I have one in series with a modern LED with the same
current flowing through both for science demos.

Blue LEDs back then were insanely expensive and very rare gallium
nitride or silicon carbide. Blue LEDs initially found favour in high end
cost no object audiophool equipment. Red were by far the cheapest.

The main way that they fail is though abuse when
bending the legs or inadequate heatsinking on the new high power LEDs.

inadequate heatsinking, yes perhaps that's it, as I said.
If the heatsinking were adequate they could be left on longer.

You are misreading the information. They can run perfectly well for
extended periods. They are merely translating the 50k hrs MTBF into
something that they think people can more easily understand.

A bit like converting everything into London double decker buses,
Olympic swimming pools or the area of Wales. I never found these
"helpful" Blue Peter style comparisons at all useful.

3 years is about the maximum life of the current CFLs. High power
production LED lamps haven't been around long enough for you to have had
one fail with three years of use unless you are an incredibly early
adopter with money to burn or an insider at a research lab.

Makes you wonder how they work out they'll last 25 years doesn't it.

Engineering methods and accelerated testing.

Mine weren't the high power production LEDs.

The corresponding numbers for each technology and a nominal 60W bulb
operated 24/7 based on manufacturers claimed MTBF are as follows:

NOT for LEDS their life times are quoted for 4 hours per day or less.

Rubbish. I can believe that the lifetime of the control electronics will
be limited a bit by continuous usage but the LED reaches thermal
equilibrium

So what we're talking abouyt what you buy not individual parts.

If the control circurty fails how much will it cost to replace it.

You can't - no user servicable parts.

your not one of these crackpots selling this crap on ebay are you.
A friend opf mione spent quite a bit on such LEDS shipped from china 20% failed in under a month, mosty likely fakes.

No. Of course not. I have pointed mostly to Philips and Samsung units on
Amazon which I have found to be good.

very quickly after being switched on. The capacitors will
dry out slightly faster when warm but in a good design they are well
within limits. I don't doubt there are some bad ones out there too.

In those you have quoted, why only quote for them if left on for a few hours a day ?

They didn't. You are reading something into it that is *NOT* there.

In actual fact traditional filament bulbs will probably last a fair bit
longer when left on continuously than makers normal use MTBF and solid
state electronics may expire sooner.

Yes much sooner.


The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Me too, I won't be buying them just yet. I'll wait for the real users results.

Make your mind up! Just below you also say you have bought four!!!

Every year or so we get new higher efficiency bulbs.

Yes. But if you buy an LED now instead of a CFL you will be ahead after
under two years including the electricity used - and the savings are
even better if you are not on an optimum low use tariff.

Depends on the use, I have little use for LEDs bulbs in the home
as for efficint lighting.

You could try writing that again in English.

I've brought 4 LEDs tubes, be intersting to see how they do.

So far so good is my experience.

Haven't installed them yet.

Or even bought them if your earlier claim is correct.

--
Regards,
Martin Brown

In article ,
whisky-dave wrote:
I have yet to see an LED fail of old age and I have some original ones

from the early 70s.

They must be very original then, there were few about in the early 70s
and non were meant for mains lighting.

They weren't designed for lighting at all. Merely signal lamps. And not
'white'. So their life is of absolutely no significance as regards this
discussion.

--
*I brake for no apparent reason.

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

On 09/07/2013 20:31, Dave Plowman (News) wrote:
In article ,
whisky-dave wrote:

I have yet to see an LED fail of old age and I have some original ones
from the early 70s.

They must be very original then, there were few about in the early 70s
and non were meant for mains lighting.

They weren't designed for lighting at all. Merely signal lamps. And not
'white'. So their life is of absolutely no significance as regards this
discussion.

Compared to the bulbs they replaced they were wonderful though and
lasted almost forever. "Green" was more dark lemon yellow. It is only
comparatively recently that a true green and cyan have been possible.

The modern white LEDs are mostly blue with a wideband yellow phosphor
and mostly fail by degrading the clear plastic encapsulation and/or
darkening the phosphor closest to semiconductor die.

In practice I think the capacitors will be the weakest link on any
properly designed high power mains LED bulb.

--
Regards,
Martin Brown

In article ,
Martin Brown wrote:
They weren't designed for lighting at all. Merely signal lamps. And not
'white'. So their life is of absolutely no significance as regards this
discussion.

Compared to the bulbs they replaced they were wonderful though and
lasted almost forever. "Green" was more dark lemon yellow. It is only
comparatively recently that a true green and cyan have been possible.

Decent quality under-run tungsten can have a very long life too. The LEDs
which replaced signal lamps cost many times the price of tungsten. Better
quality tungsten would have provided a more reasonable comparison. And, of
course, LEDs didn't replace tungsten where actual light was needed - like
say for a panel meter.

--
*Your kid may be an honours student, but you're still an idiot.

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

On 09/07/2013 22:50, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
They weren't designed for lighting at all. Merely signal lamps. And not
'white'. So their life is of absolutely no significance as regards this
discussion.

Compared to the bulbs they replaced they were wonderful though and
lasted almost forever. "Green" was more dark lemon yellow. It is only
comparatively recently that a true green and cyan have been possible.

Decent quality under-run tungsten can have a very long life too. The LEDs
which replaced signal lamps cost many times the price of tungsten. Better
quality tungsten would have provided a more reasonable comparison. And, of
course, LEDs didn't replace tungsten where actual light was needed - like
say for a panel meter.

Tungsten hasn't (yet, and to the best of my knowledge) beaten carbon
filament - at 110 years or more. And that is probably very much
under-run - or the filament was over-sized.

--
Rod

On Wednesday, July 10, 2013 9:56:51 AM UTC+12, polygonum wrote:

Tungsten hasn't (yet, and to the best of my knowledge) beaten carbon

filament - at 110 years or more. And that is probably very much

under-run - or the filament was over-sized.

I found a cupboard with unused carbon filament lightbulbs in their original packets, dating from around 1902. They will be handy when the ones we are using burn out!

On Tue, 09 Jul 2013 16:03:37 +0100 (BST), "Dave Liquorice"
wrote:

On Tue, 09 Jul 2013 08:12:42 +0100, Martin Brown wrote:

Comparing electricity prices is a PITA all the online comparison sites
want way too much detail from you before they will allow you to see any
of the numbers!

Like what, to give meaningful results they need to know where in the
country you are, who your current supplier is and the current tariff
name and a fairly accurate annual usage.

I wonder why energy prices should vary dependent on where you are in
the country? I could understand why it might cost more to provide it
on a remote island, but not from one mainland county to another.

But yes, getting the real figures to plug into your own spreadsheet
can be a PITA but it's normally easier on a comparison site than the
direct with the supplier. They quite often have a single 60 page .pdf
with electricity only, duel fuel, gas only with every tariff for each
of those and all the variations that arise from the 16 electricity
regions. The comparison sites at least filter all that irrelevant
information quite well.

Indeed. But I am often not convinced the comparison sites are
correct. Have you ever actually saved the amount that the site said
you would?
--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On Tue, 09 Jul 2013 15:50:15 +0100, Martin Brown wrote:

On 09/07/2013 15:08, Adrian wrote:
On Tue, 09 Jul 2013 14:40:24 +0100, Martin Brown wrote:

The jury is still out on that one. I haven't owned any for long enough
to see a single LED unit failure yet. CFLs on the other hand expire
after ~3 years in normal use due to tube failure or capacitor
degradation and I have enough to be pretty sure of the statistics.

Ah, hold on whilst I just rummage around for the GU10ish-form-factor LED
bulb that I've just lobbed.

I don't know how old it is/was, but of the 7 or 8 individual LEDs within
it, only two were still working. "Megaman" brand.

That would be the sort that you put in a position designed for a halogen
lamp. I have already said that they will expire quickly!

I am only considering well engineered units in sensible free air or
fixtures designed with LED heatsinking requirements in mind.

Precisely, which is why LEDs are not suitable in many cases as direct
replacements for GLS/CFL. In other words, change all your fittings to suit
our lamps.
The 3.5W Aldi LED gets hot in a metal socket in a metal, ventilated shade.
LEDs are astoundingly inefficient. Any source of light that generates heat
as well should be rated for inefficiency, not efficiency.
--
Peter.
The gods will stay away
whilst religions hold sway

On Wed, 10 Jul 2013 08:59:09 +0100, Mark wrote:

But yes, getting the real figures to plug into your own spreadsheet
can be a PITA but it's normally easier on a comparison site than the
direct with the supplier. They quite often have a single 60 page .pdf
with electricity only, duel fuel, gas only with every tariff for each
of those and all the variations that arise from the 16 electricity
regions. The comparison sites at least filter all that irrelevant
information quite well.

Indeed. But I am often not convinced the comparison sites are
correct. Have you ever actually saved the amount that the site said
you would?

Sort of. I was promised a -£5 saving, so in the spirit of negativity I
didn't take up the offer and thus saved saving -£5.
--
Peter.
The gods will stay away
whilst religions hold sway

On 10/07/2013 09:54, PeterC wrote:
The 3.5W Aldi LED gets hot in a metal socket in a metal, ventilated shade.
LEDs are astoundingly inefficient. Any source of light that generates heat
as well should be rated for inefficiency, not efficiency.

I'd be interested to see how you would rate inefficiency of, say, GLS,
halogen, CFL, and LED.

At the moment I am struggling to understand how an LED rated at 3.5W
could be expected to dissipate more than 3.5W of heat even if it were
wrapped up in an aluminium foil overcoat. Certainly that would be zero
percent efficient at emitting light, but nonetheless a small overall
loss compared against, say a 60W GLS.

--
Rod

On 10/07/2013 10:03, polygonum wrote:
On 10/07/2013 09:54, PeterC wrote:
The 3.5W Aldi LED gets hot in a metal socket in a metal, ventilated
shade.
LEDs are astoundingly inefficient. Any source of light that generates
heat as well should be rated for inefficiency, not efficiency.

No they are fairly efficient probably around 30-50 lumen/watt against
the very best LEDs now in production which are now about 80-100
lumen/watt. Research devices have managed much better.

I'd be interested to see how you would rate inefficiency of, say, GLS,
halogen, CFL, and LED.

This is dated 2001 and when I did it only green semiconductor LEDs were
anything close to competitive. Now high power white LEDs have overtaken
metal halide efficacy in production LED bulbs available for retail.

http://www.nezumi.demon.co.uk/lightpollution/lights.htm

At the moment I am struggling to understand how an LED rated at 3.5W
could be expected to dissipate more than 3.5W of heat even if it were
wrapped up in an aluminium foil overcoat. Certainly that would be zero
percent efficient at emitting light, but nonetheless a small overall
loss compared against, say a 60W GLS.

The problem is that whereas the 60W GLS emits some light 12Lm/W and a
very great deal of IR and some warm air it can tolerate very high
operating temperatures on the glass envelope without any difficulty. You
can feel the IR heat radiation in the beam of a spotlight.

The LED consumes 3.5W emits 40Lm/W no short wavelength IR and just
increases its temperature until warm air rising or the enclosure can
radiate it away. Radiation losses scale as T^4 and don't really become
significant until 50C or above so you need free air flow for cooling.
The LED bulb is in trouble if its temperature exceeds boiling point.

Put it inside a well insulated luminaire designed to protect timber from
insanely hot halogen lamps and you have a recipe for disaster.

A "perfect" optimised monochromatic lamp would give about 700Lm/W. If it
has to be white then as a black body 100Lm/W is the limit but if you can
cheat and only emit visible light then 250Lm/W is the target to aim for.
For a very long time the most efficient lamp was a large ~100W low
pressure sodium street lamp at 200Lm/W.

But the white LED technology is still improving all the time and Cree
have claimed one in the lab at close to 100% thermodynamic efficiency:

http://ledsmagazine.com/news/10/2/16

Depending on what you set as the target for maximum white light
efficiency the incandescent is 5-10% efficient and the latest consumer
LEDs 20-35% efficient at turning electricity into white light. That
still means the majority of power used is turned into waste heat.

Things are much worse if it has a nice shiny metallic surface finish on
the heatsink as that prevents thermal radiation getting away.

--
Regards,
Martin Brown

On 10/07/2013 11:27, Martin Brown wrote:
Depending on what you set as the target for maximum white light
efficiency the incandescent is 5-10% efficient and the latest consumer
LEDs 20-35% efficient at turning electricity into white light. That
still means the majority of power used is turned into waste heat.

Quite. Which is why I questioned the statement "LEDs are astoundingly
inefficient".

--
Rod

On Tuesday, 9 July 2013 18:07:39 UTC+1, Martin Brown wrote:
On 09/07/2013 17:10, whisky-dave wrote:

On Tuesday, 9 July 2013 14:40:24 UTC+1, Martin Brown wrote:

On 09/07/2013 13:49, whisky-dave wrote:



On Monday, 8 July 2013 14:58:30 UTC+1, Martin Brown wrote:



On 08/07/2013 14:04, whisky-dave wrote:



On Monday, 8 July 2013 09:47:13 UTC+1, Martin Brown wrote:



On 04/07/2013 22:41, Dave Liquorice wrote:



http://www.amazon.co.uk/Philips-Visi...pd_sim_light_8



"this equates to about 25 years if used for a few hours per day."



So in the real world pretty useless I'd say, for me anyway.



How do you arrive at that conclusion?



Because if I'm to save money the bulbs have to be onb a significant amoubt of time. If you leave LEDS on for that long their life shortens quite quickily.



"Long life 25000 hour or ten year lifespan in normal use means they last much longer than ordinary bulbs, this equates to about 25 years if used for a few hours per day."



I've had LEDS go in under 3 years. I want their estimate of the LEDs life if they were on 6-8 hours per day.



I have yet to see an LED fail of old age and I have some original ones

from the early 70s.



They must be very original then, there were few about in the early 70s and non were meant for mains lighting.

In 1978/9 blue LEDS were about £30 each.



They are original red, yellow and green (the green isn't good at all)

from about 1974.

Those weren't meant for dometsic home use were they. So little point in comparing them with todays range.


I have one in series with a modern LED with the same

current flowing through both for science demos.

what does that demo ?
Last week I ordered 4,000+ LEDs .

Blue LEDs back then were insanely expensive and very rare gallium

nitride or silicon carbide. Blue LEDs initially found favour in high end

cost no object audiophool equipment. Red were by far the cheapest.

yes, now we have 'shades' and tempratures of WHITE they weren't availble in the mids 70s more like the mid 90s.


The main way that they fail is though abuse when

bending the legs or inadequate heatsinking on the new high power LEDs.



inadequate heatsinking, yes perhaps that's it, as I said.

If the heatsinking were adequate they could be left on longer.



You are misreading the information. They can run perfectly well for

extended periods.

So why say if run for a few hours a day6, have you ever seen such a standment of CFL or tungsten.


They are merely translating the 50k hrs MTBF into

something that they think people can more easily understand.

No they aren't, it's a marketing ply to the stupid they can buy a bulb for £10 that'll last them 25 years and save them money........


Makes you wonder how they work out they'll last 25 years doesn't it.



Engineering methods and accelerated testing.

Which doesn't equate to home use.

If they really did last anywhere near the quoted life span then they'd be willing to guarantee them, but so far they haven't why ?



Rubbish. I can believe that the lifetime of the control electronics will

be limited a bit by continuous usage but the LED reaches thermal

equilibrium



So what we're talking abouyt what you buy not individual parts.



If the control circurty fails how much will it cost to replace it.



You can't - no user servicable parts.

Exactly.


your not one of these crackpots selling this crap on ebay are you.

A friend opf mione spent quite a bit on such LEDS shipped from china 20% failed in under a month, mosty likely fakes.



No. Of course not. I have pointed mostly to Philips and Samsung units on

Amazon which I have found to be good.

OK then you can be the test then.



very quickly after being switched on. The capacitors will

dry out slightly faster when warm but in a good design they are well

within limits. I don't doubt there are some bad ones out there too.



In those you have quoted, why only quote for them if left on for a few hours a day ?



They didn't. You are reading something into it that is *NOT* there.

IT IS THERE READ IT.


In actual fact traditional filament bulbs will probably last a fair bit

longer when left on continuously than makers normal use MTBF and solid

state electronics may expire sooner.



Yes much sooner.





The jury is still out on that one. I haven't owned any for long enough

to see a single LED unit failure yet. CFLs on the other hand expire

after ~3 years in normal use due to tube failure or capacitor

degradation and I have enough to be pretty sure of the statistics.



Me too, I won't be buying them just yet. I'll wait for the real users results.



Make your mind up! Just below you also say you have bought four!!!

I did for work we want to test them too. LED tubes.

I have a light meter at the ready, but unfortunalty the college blinds
don;t keep out much light which makes it difficult to compare them with the 'normal' at this time of year the ones we get supplied for NOTHING.
If I am to replace them all I need 84 for the labs and 16 for the offices.
I can't just spend nearly £5K just because they last longer providing we don't use them as much.


Every year or so we get new higher efficiency bulbs.



Yes. But if you buy an LED now instead of a CFL you will be ahead after

under two years including the electricity used - and the savings are

even better if you are not on an optimum low use tariff.



Depends on the use, I have little use for LEDs bulbs in the home

as for efficint lighting.



You could try writing that again in English.

I have little use for LEDs as lighting in the home.
from my experince they do NOT give the same quality of light either, I do not see them as more efficient yet, unless willing to pay a lot more for the lastest models.



I've brought 4 LEDs tubes, be intersting to see how they do.
So far so good is my experience.
Haven't installed them yet.



Or even bought them if your earlier claim is correct.

TUBES not bulbs brought them in April for work NOT the home.


http://onecall.farnell.com/energenie...-cw/dp/LA04450


anyway I think the future is with PLEDs for lighting and OLEDs for gadgets.

On Wed, 10 Jul 2013 10:03:31 +0100, polygonum wrote:

On 10/07/2013 09:54, PeterC wrote:
The 3.5W Aldi LED gets hot in a metal socket in a metal, ventilated shade.
LEDs are astoundingly inefficient. Any source of light that generates heat
as well should be rated for inefficiency, not efficiency.

I'd be interested to see how you would rate inefficiency of, say, GLS,
halogen, CFL, and LED.

At the moment I am struggling to understand how an LED rated at 3.5W
could be expected to dissipate more than 3.5W of heat even if it were
wrapped up in an aluminium foil overcoat. Certainly that would be zero
percent efficient at emitting light, but nonetheless a small overall
loss compared against, say a 60W GLS.

The plastic(?) part is just hot to touch, i.e. a bit more than warm, so I'd
assume up in the 50s given the poor conductivity of the surface. The metal
shade is just warm around the base of the lamp (~24C in here atm).

I tried it with a Maplin plug-in meter, expecting a poor PF: it was, at
about 0.6, but the readings were 2W and 3VA. I suspect that the meter
doesn't like the circuitry.
--
Peter.
The gods will stay away
whilst religions hold sway

On Wed, 10 Jul 2013 11:27:43 +0100, Martin Brown wrote:

On 10/07/2013 10:03, polygonum wrote:
On 10/07/2013 09:54, PeterC wrote:
The 3.5W Aldi LED gets hot in a metal socket in a metal, ventilated
shade.
LEDs are astoundingly inefficient. Any source of light that generates
heat as well should be rated for inefficiency, not efficiency.

No they are fairly efficient probably around 30-50 lumen/watt against
the very best LEDs now in production which are now about 80-100
lumen/watt. Research devices have managed much better.

I'd be interested to see how you would rate inefficiency of, say, GLS,
halogen, CFL, and LED.

This is dated 2001 and when I did it only green semiconductor LEDs were
anything close to competitive. Now high power white LEDs have overtaken
metal halide efficacy in production LED bulbs available for retail.

http://www.nezumi.demon.co.uk/lightpollution/lights.htm

At the moment I am struggling to understand how an LED rated at 3.5W
could be expected to dissipate more than 3.5W of heat even if it were
wrapped up in an aluminium foil overcoat. Certainly that would be zero
percent efficient at emitting light, but nonetheless a small overall
loss compared against, say a 60W GLS.

The problem is that whereas the 60W GLS emits some light 12Lm/W and a
very great deal of IR and some warm air it can tolerate very high
operating temperatures on the glass envelope without any difficulty. You
can feel the IR heat radiation in the beam of a spotlight.

The LED consumes 3.5W emits 40Lm/W no short wavelength IR and just
increases its temperature until warm air rising or the enclosure can
radiate it away. Radiation losses scale as T^4 and don't really become
significant until 50C or above so you need free air flow for cooling.
The LED bulb is in trouble if its temperature exceeds boiling point.

Put it inside a well insulated luminaire designed to protect timber from
insanely hot halogen lamps and you have a recipe for disaster.

A "perfect" optimised monochromatic lamp would give about 700Lm/W. If it
has to be white then as a black body 100Lm/W is the limit but if you can
cheat and only emit visible light then 250Lm/W is the target to aim for.
For a very long time the most efficient lamp was a large ~100W low
pressure sodium street lamp at 200Lm/W.

But the white LED technology is still improving all the time and Cree
have claimed one in the lab at close to 100% thermodynamic efficiency:

http://ledsmagazine.com/news/10/2/16

Depending on what you set as the target for maximum white light
efficiency the incandescent is 5-10% efficient and the latest consumer
LEDs 20-35% efficient at turning electricity into white light. That
still means the majority of power used is turned into waste heat.

Things are much worse if it has a nice shiny metallic surface finish on
the heatsink as that prevents thermal radiation getting away.

This fitting is a somewhat shiny filing-cabinet grey, so not extreme.

Useful information, thanks. I'm very interested in LEDs (started using them
back in the '80s at work for indicating lights on machinery etc.) but also
rather disappointed in how far they haven't come in 30 years.
--
Peter.
The gods will stay away
whilst religions hold sway

On 10/07/2013 17:42, PeterC wrote:
On Wed, 10 Jul 2013 11:27:43 +0100, Martin Brown wrote:

Depending on what you set as the target for maximum white light
efficiency the incandescent is 5-10% efficient and the latest consumer
LEDs 20-35% efficient at turning electricity into white light. That
still means the majority of power used is turned into waste heat.

Things are much worse if it has a nice shiny metallic surface finish on
the heatsink as that prevents thermal radiation getting away.

This fitting is a somewhat shiny filing-cabinet grey, so not extreme.

Anything that isn't shiny metallic is a pretty good "black" in the
thermal IR band (except possibly for some specialised military paints).

Useful information, thanks. I'm very interested in LEDs (started using them
back in the '80s at work for indicating lights on machinery etc.) but also
rather disappointed in how far they haven't come in 30 years.

They have come a long way in that time. The early ones could only handle
about 10mA if that and were dim as anything. Modern ones are brighter by
more than an order of magnitude at the same current.

One handy trick if you live somewhere prone to power cuts is to bridge
the switch on an LED torch with a 470k resistor. This makes the LED glow
just enough to find the torch in total darkness without losing any
noticeable battery life. You can see by it when fully dark adapted.

--
Regards,
Martin Brown

On Wed, 10 Jul 2013 08:59:09 +0100, Mark wrote:

I wonder why energy prices should vary dependent on where you are in
the country?

The 14(*) distribution regions charge differing amounts to the
suppliers to distribute the power from the National Grid to the end
user.

Indeed. But I am often not convinced the comparison sites are
correct. Have you ever actually saved the amount that the site said
you would?

They are ball park and as I can give them fairly accurate usage
information not bad, ie within a fiver. I use the comparison sites as
a filter to find the cheapest half dozen or so tariffs. I then get
the real figures for those tariffs and plug them into my spreadsheet.
The last time I swapped suppliers the total monthly payments dropped
from £295 to £187.

(*) 14 regions but only 9 actual companies, though I should imagine
each region "owned" by the same DNO is operated as completely
separate entities.

--
Cheers
Dave.

On Wed, 10 Jul 2013 05:31:46 -0700 (PDT), whisky-dave wrote:

http://onecall.farnell.com/energenie...tube-t8-150cm-
23w-cw/dp/LA04450

Are they a straight swap or do you need to change the control gear in
the fitting as well?

--
Cheers
Dave.

On Wed, 10 Jul 2013 22:18:23 +0100, Martin Brown wrote:

Useful information, thanks. I'm very interested in LEDs (started using them
back in the '80s at work for indicating lights on machinery etc.) but also
rather disappointed in how far they haven't come in 30 years.

They have come a long way in that time. The early ones could only handle
about 10mA if that and were dim as anything. Modern ones are brighter by
more than an order of magnitude at the same current.

Oh, I accept that. It's just the fact that they still waste energy as heat
and can't give omnidirectional light.

One handy trick if you live somewhere prone to power cuts is to bridge
the switch on an LED torch with a 470k resistor. This makes the LED glow
just enough to find the torch in total darkness without losing any
noticeable battery life. You can see by it when fully dark adapted.

Interesting tip, thanks. I have several torches around the place (the
cylindrical ones from pound shops, rubber push-button on the end, are v.
good for the price) and I seem to locate items accurately in darkness (no
SWMBO to 'tidy up') but in a situation of necessity the glow would be good.
The desk lamp mentioned up thread has a switch that glows green - saves
having to turn on a light...
--
Peter.
The gods will stay away
whilst religions hold sway

On Wed, 10 Jul 2013 23:09:35 +0100 (BST), "Dave Liquorice"
wrote:

On Wed, 10 Jul 2013 08:59:09 +0100, Mark wrote:

I wonder why energy prices should vary dependent on where you are in
the country?

The 14(*) distribution regions charge differing amounts to the
suppliers to distribute the power from the National Grid to the end
user.

Next question: Why do the distribution regions charge different
amounts? ;-)

--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On Thu, 11 Jul 2013 08:44:26 +0100, Mark
wrote:

On Wed, 10 Jul 2013 23:09:35 +0100 (BST), "Dave Liquorice"
wrote:

On Wed, 10 Jul 2013 08:59:09 +0100, Mark wrote:

I wonder why energy prices should vary dependent on where you are in
the country?

The 14(*) distribution regions charge differing amounts to the
suppliers to distribute the power from the National Grid to the end
user.

Next question: Why do the distribution regions charge different
amounts? ;-)

I'd guess that it's historical. The regions match the old electricity
boards, who had different tariffs as they were distinct entities;
presumably they had different costs to justify that.

I've no doubt that providers just use the regions as a means of
maintaining profits, I can't imagine that there is any realistic cost
basis for the variations any longer.

On Wednesday, 10 July 2013 23:15:46 UTC+1, Dave Liquorice wrote:
On Wed, 10 Jul 2013 05:31:46 -0700 (PDT), whisky-dave wrote:



http://onecall.farnell.com/energenie...tube-t8-150cm-

23w-cw/dp/LA04450



Are they a straight swap or do you need to change the control gear in

the fitting as well?

According to the information supplied they should fit and work.
https://energysavingshop.confused.co...t/ENER303-23T8

I also read up that there could be problems with rotating machinery and that sometimes the reflectors need changing although I've yet to work out how a reflector would stop flickering but perhaps it's a reflector diffuser type coating.

On Thu, 11 Jul 2013 08:44:26 +0100, Mark wrote:

The 14(*) distribution regions charge differing amounts to the
suppliers to distribute the power from the National Grid to the
end
user.

Next question: Why do the distribution regions charge different
amounts? ;-)

Differing costs in distribution. You have less cost per customer
served in an urban area compared to a rural one. Take the average
residential street with the 10 yd frontage, 170 odd customers per
mile. Around here they are lucky to get 2 or 3 customers per mile.
Some regions are predominantly rural others have the huge
conurbations and little rural.

--
Cheers
Dave.

On Thu, 11 Jul 2013 18:03:31 +0100 (BST), "Dave Liquorice"
wrote:

On Thu, 11 Jul 2013 08:44:26 +0100, Mark wrote:

The 14(*) distribution regions charge differing amounts to the
suppliers to distribute the power from the National Grid to the
end
user.

Next question: Why do the distribution regions charge different
amounts? ;-)

Differing costs in distribution. You have less cost per customer
served in an urban area compared to a rural one. Take the average
residential street with the 10 yd frontage, 170 odd customers per
mile. Around here they are lucky to get 2 or 3 customers per mile.
Some regions are predominantly rural others have the huge
conurbations and little rural.

Interesting theory but I don't think the stats bear it out. For
example Northern Scotland has slightly cheaper prices than London.
--
(\__/) M.
(='.'=) If a man stands in a forest and no woman is around
(")_(") is he still wrong?

On Thursday, 11 July 2013 18:03:31 UTC+1, Dave Liquorice wrote:
On Thu, 11 Jul 2013 08:44:26 +0100, Mark wrote:



The 14(*) distribution regions charge differing amounts to the

suppliers to distribute the power from the National Grid to the

end

user.



Next question: Why do the distribution regions charge different

amounts? ;-)



Differing costs in distribution. You have less cost per customer

served in an urban area compared to a rural one. Take the average

residential street with the 10 yd frontage, 170 odd customers per

mile. Around here they are lucky to get 2 or 3 customers per mile.

Some regions are predominantly rural others have the huge

conurbations and little rural.

What about dividents for shareholders and other perks for managers and employees, surely such things are similar to supermarkets why should a loaf of bread be cheaper in one shop than another if they are next door ?

On Tue, 9 Jul 2013 19:09:41 -0700 (PDT), Matty F wrote:

I found a cupboard with unused carbon filament lightbulbs in their
original packets, dating from around 1902. They will be handy when the
ones we are using burn out!

Didn't early light bulbs have a fairly hard vacuum "filling". Modern
bulbs are gas filled, AIUI the gas filling enables better cooling of
the filament but shortens the life, maybe by enabling the filament to
be much finer and run hotter.

--
Cheers
Dave.

On Mon, 08 Jul 2013 09:53:52 +0100, Martin Brown
wrote:

The ones with the chunkiest heatsinks in fittings with nice airflow will
last a good long time.

Yep; the Chinese 7W (7x1W) PAR30s I bought months ago haven't failed
yet and, to make sure of that, I left them on around the clock for
days on end - reasoning that early failure would be weeded out that
way. Their normal duty is many hours per day anyway - at least, until
the start of summer. They still survive, and I reckon on buying more
from the same seller on ebay -
http://myworld.ebay.co.uk/yescompany...84.m1423.l2754
I also found, not entirely unexpectedly, that cheaping out on Chinese
LEDs just isn't worthwhile - yescompany's ones seem ok, but trying to
save even more money is full of pitfalls. Of three LED bulbs from
fasttech, two have failed in short order. They are good at refunds
and/or replacement, depending on what I want, but I'd rather not have
to.

On Wed, 10 Jul 2013 17:42:09 +0100, PeterC
wrote:

Useful information, thanks. I'm very interested in LEDs (started using them
back in the '80s at work for indicating lights on machinery etc.) but also
rather disappointed in how far they haven't come in 30 years.

(eyes collection of LED torches)
I would have killed for such an assortment of cheap reliable portable
lighting 30 years ago.