I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

Hmm.
--
Roland Perry

Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

If the MTBF is 25k hours that means some proportion of them are going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.

I suppose this is the hazard of fitting lights with unreplaceable lamps - it
only takes one of them to die to make the rest of the installation look
bad.

Theo

On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

If the MTBF is 25k hours that means some proportion of them are going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.

I suppose this is the hazard of fitting lights with unreplaceable lamps - it
only takes one of them to die to make the rest of the installation look
bad.

GU10 suggests replaceable lamps rather than permanent ones. The usual
problem with LED lamps is their ability to shed heat, and that is
heavily dictated by the enclosure. Many GU10 fittings will leave the
lamp completely exposed - and one would expect that to give adequate
cooling. Fully enclosed in a downlighter - especially if covered in
insulation could result in much higher run temperatures and so
dramatically shorter life expectancy.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message , at
12:04:27 on Sat, 13 Feb 2021, John Rumm
remarked:
On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.
If the MTBF is 25k hours that means some proportion of them are
going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.
I suppose this is the hazard of fitting lights with unreplaceable
lamps - it
only takes one of them to die to make the rest of the installation look
bad.

GU10 suggests replaceable lamps rather than permanent ones.

That's right - theyare easily replaced.

The usual problem with LED lamps is their ability to shed heat, and
that is heavily dictated by the enclosure. Many GU10 fittings will
leave the lamp completely exposed - and one would expect that to give
adequate cooling. Fully enclosed in a downlighter - especially if
covered in insulation could result in much higher run temperatures and
so dramatically shorter life expectancy.

Being in the ceiling of an extension they are very well insulated to the
side and above.
--
Roland Perry

On 14/02/2021 06:28, Roland Perry wrote:
In message , at
12:04:27 on Sat, 13 Feb 2021, John Rumm
remarked:
On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They
start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.
Â*If the MTBF is 25k hours that means some proportion of them are
going to
fail before 25k hours.Â* If that was a median TBF it would be half of
them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.
Â*I suppose this is the hazard of fitting lights with unreplaceable
lamps - it
only takes one of them to die to make the rest of the installation look
bad.

GU10 suggests replaceable lamps rather than permanent ones.

That's right - theyare easily replaced.

The usual problem with LED lamps is their ability to shed heat, and
that is heavily dictated by the enclosure. Many GU10 fittings will
leave the lamp completely exposed - and one would expect that to give
adequate cooling. Fully enclosed in a downlighter - especially if
covered in insulation could result in much higher run temperatures and
so dramatically shorter life expectancy.

Being in the ceiling of an extension they are very well insulated to the
side and above.

And fire-rated (which tends to mean reduced ventilation)?

--
Robin
reply-to address is (intended to be) valid

So, how hot do they get? Does seem to me that they have not been designed
with a typical use condition in the first place. What actually fails, I
wonder. Do they have a psu or is it strictly diodes and some kind of over
voltage protection with them all in series?
Brian

--

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

Blind user, so no pictures please
Note this Signature is meaningless.!
"Roland Perry" wrote in message
...
In message , at
12:04:27 on Sat, 13 Feb 2021, John Rumm
remarked:
On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They
start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.
If the MTBF is 25k hours that means some proportion of them are going
to
fail before 25k hours. If that was a median TBF it would be half of
them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.
I suppose this is the hazard of fitting lights with unreplaceable
lamps - it
only takes one of them to die to make the rest of the installation look
bad.

GU10 suggests replaceable lamps rather than permanent ones.

That's right - theyare easily replaced.

The usual problem with LED lamps is their ability to shed heat, and that
is heavily dictated by the enclosure. Many GU10 fittings will leave the
lamp completely exposed - and one would expect that to give adequate
cooling. Fully enclosed in a downlighter - especially if covered in
insulation could result in much higher run temperatures and so
dramatically shorter life expectancy.

Being in the ceiling of an extension they are very well insulated to the
side and above.
--
Roland Perry

On 14/02/2021 09:03, Brian Gaff (Sofa) wrote:

So, how hot do they get? Does seem to me that they have not been designed
with a typical use condition in the first place.

That's the problem, in reality they were not designed for LED lamps.

So GU10 LED lamps are a retrofit option, but many existing lamp holders
were not designed to facilitate adequate cooling of the lamps.

What actually fails, I
wonder. Do they have a psu or is it strictly diodes and some kind of over
voltage protection with them all in series?

Usually the capacitors in the PSUs fail at high temperatures.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 14/02/2021 09:03, Brian Gaff (Sofa) wrote:
So, how hot do they get? Does seem to me that they have not been designed
with a typical use condition in the first place.

Get a 1W rated resistor and dissipate 1W through it and see how hot it
gets.


In this case the size of the bulb and the type of fitting are the
problem. The LED equivalent bulbs have not been designed from new but as
a replacement to fit in an existing fitting. The only physical
connections are two lugs for the electrical supply and therefore cannot
be optimised for maximum heat sinking. This coupled with their small
size and usually in housings that fully enclose the bulb (apart from the
front) makes getting rid of unwanted heat from the bulb difficult.



What actually fails, I
wonder. Do they have a psu or is it strictly diodes and some kind of over
voltage protection with them all in series?

Both LEDs and power supplies fail if they get too hot. In the very small
bulbs there may be a couple of capacitors, a bridge rectifier and a few
resistors all packed into a space much smaller than the top of your
little finger. Often one of the capacitors is an electrolytic type.

In panel type lights that have been designed for LEDS. the LEDS are
bolted directly to some metal-work. In many of the ones that I've
fitted there has been been a substantial metal backplate.

In outside flood light fittings the LED designs are completely different
from the previous halogen models. The LEDs are bolted directly to the
metal housing which provides the heat-sink.



--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

In article , Roland Perry
writes
In message , at
12:04:27 on Sat, 13 Feb 2021, John Rumm
remarked:
On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.
If the MTBF is 25k hours that means some proportion of them are
going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.
I suppose this is the hazard of fitting lights with unreplaceable
lamps - it
only takes one of them to die to make the rest of the installation look
bad.

GU10 suggests replaceable lamps rather than permanent ones.

That's right - theyare easily replaced.

The usual problem with LED lamps is their ability to shed heat, and
that is heavily dictated by the enclosure. Many GU10 fittings will
leave the lamp completely exposed - and one would expect that to give
adequate cooling. Fully enclosed in a downlighter - especially if
covered in insulation could result in much higher run temperatures and
so dramatically shorter life expectancy.

Being in the ceiling of an extension they are very well insulated to
the side and above.
I had the same issue with our extension. So up in the loft I carefully
created a space in the insulation around each fitting. Then when
boarding over I cut a circular hole over each bulb to allow the heat to
rise. Covered the hole with mesh to prevent the inevitable.
--
bert

On 13/02/2021 11:40, Theo wrote:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

If the MTBF is 25k hours that means some proportion of them are going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.


Not really, these things don't follow idealised statistical
distributions. The conditions for statistical limit theorems don't
really apply.

I thought high early fail rates are common in electrical components,
after that they may have much higher expected life times.



I suppose this is the hazard of fitting lights with unreplaceable lamps - it
only takes one of them to die to make the rest of the installation look
bad.


Yep.

On 13/02/2021 11:40, Theo wrote:

I suppose this is the hazard of fitting lights with unreplaceable lamps

No, it shows the folly of putting LEDs in an inappropriate fitting.

GU10 downlights tend to be fittings with almost zero airflow to provide
cooling and heat kills LEDs (and the power supply electronics)


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

alan_m wrote:
On 13/02/2021 11:40, Theo wrote:

I suppose this is the hazard of fitting lights with unreplaceable lamps

No, it shows the folly of putting LEDs in an inappropriate fitting.

GU10 downlights tend to be fittings with almost zero airflow to provide
cooling and heat kills LEDs (and the power supply electronics)



About 12 years ago we had an extension built with 20 GU10 downlighters with
mains halogen bulbs. After doing a quick bit of multiplication and
realising just how much power they were using I ordered some cheap led GU10
bulbs off of eBay. Within about two months about half a dozen of them
failed. The vendor replaced them all and Ive not had a single failure
since despite these being on for many hours every day.

GU10 fittings arent the worst offenders IMO. G9 fittings on the other
hand...

Tim

--
Please don't feed the trolls

Where is this day which is over 24 hours long though?


Half the issue is often the heat, but I'd have thought in a normal
installation they would be designed to have an acceptable life under such
conditions, otherwise where do you draw the line?
Brian

--

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

Blind user, so no pictures please
Note this Signature is meaningless.!
"Theo" wrote in message
...
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

If the MTBF is 25k hours that means some proportion of them are going to
fail before 25k hours. If that was a median TBF it would be half of them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.

I suppose this is the hazard of fitting lights with unreplaceable lamps -
it
only takes one of them to die to make the rest of the installation look
bad.

Theo

Brian Gaff (Sofa) wrote

Where is this day which is over 24 hours long though?

I keep it here and no, you can't use it.

Half the issue is often the heat, but I'd have thought in a normal
installation they would be designed to have an acceptable life under such
conditions, otherwise where do you draw the line?

At lending you my very useful day.

"Theo" wrote in message
...
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

If the MTBF is 25k hours that means some proportion of them are going to
fail before 25k hours. If that was a median TBF it would be half of
them.
But they've run about 3k hours, so it's hard to think of a distribution
where a third of them would have failed at that point.

I suppose this is the hazard of fitting lights with unreplaceable lamps -
it
only takes one of them to die to make the rest of the installation look
bad.

Theo

On Mon, 15 Feb 2021 03:58:50 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH the trolling senile cretin's latest troll**** unread

--
Marland addressing senile Rodent's tall stories:
"Do you really think people believe your stories you come up with to boost
your self esteem."
Message-ID:

On 14/02/2021 08:58, Brian Gaff (Sofa) wrote:
Where is this day which is over 24 hours long though?


Half the issue is often the heat, but I'd have thought in a normal
installation they would be designed to have an acceptable life under such
conditions, otherwise where do you draw the line?

Existing fittings are designed for different operating conditions. They
are designed to survive high operating temperatures and not necessarily
to cool the bulb.

Downlighters designed for LEDs don't have replaceable bulbs! This is how
adequate heat-sinking is achieved because the LED can be in physical
contact with the metal of the fitting. It also allows the power supply
electronics to be removed away from the LEDs so one is not necessarily
directly heating the other.

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.


Average doesn't mean minimum. I expect 25k hrs is average under ideal
conditions. Having 4 fail in under 3k hrs seems surprising, but maybe
not that surprising.

Why did they only send two replacements? If 4 failed in under 2 years
they should send 4.

FWIW I have about ordered about 30 GU10 LED in the last 2 years,
cheapest I could find, none have failed. At about £1.5 per bulb. I
wouldn't be that fussed if a few did go. Not Meridian bulbs.

Look on the bright side at least you didn't by an integral LED downlight
(why would anyone???)

On Sat, 13 Feb 2021 12:17:05 +0000, Pancho
wrote:

On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.


Average doesn't mean minimum. I expect 25k hrs is average under ideal
conditions. Having 4 fail in under 3k hrs seems surprising, but maybe
not that surprising.

Why did they only send two replacements? If 4 failed in under 2 years
they should send 4.

FWIW I have about ordered about 30 GU10 LED in the last 2 years,
cheapest I could find, none have failed. At about £1.5 per bulb. I
wouldn't be that fussed if a few did go. Not Meridian bulbs.

Look on the bright side at least you didn't by an integral LED downlight
(why would anyone???)

I have had a very low failure rate. As others have suggested, it
seems to depend on whether the bulb is sufficiently ventilated. As a
matter of interest, does anyone know whether LEDs situated outside
last for longer?

On 13/02/2021 12:42, Scott wrote:
On Sat, 13 Feb 2021 12:17:05 +0000, Pancho
wrote:

On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.


Average doesn't mean minimum. I expect 25k hrs is average under ideal
conditions. Having 4 fail in under 3k hrs seems surprising, but maybe
not that surprising.

Why did they only send two replacements? If 4 failed in under 2 years
they should send 4.

FWIW I have about ordered about 30 GU10 LED in the last 2 years,
cheapest I could find, none have failed. At about £1.5 per bulb. I
wouldn't be that fussed if a few did go. Not Meridian bulbs.

Look on the bright side at least you didn't by an integral LED downlight
(why would anyone???)

I have had a very low failure rate. As others have suggested, it
seems to depend on whether the bulb is sufficiently ventilated. As a
matter of interest, does anyone know whether LEDs situated outside
last for longer?


Yes, I've had pretty LED table lamps run hot and fail, but I can't see
any reason a ceiling downlight wouldn't be well ventilated, many were
designed to handle halogen bulbs.

On 13/02/2021 12:57, Pancho wrote:

Yes, I've had pretty LED table lamps run hot and fail, but I can't see
any reason a ceiling downlight wouldn't be well ventilated, many were
designed to handle halogen bulbs.


But not to provide any cooling for the bulb. The fitting is designed to
run hot as can be seen with ceramic bulb fitting (rather than plastic)

--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 13/02/2021 13:38, alan_m wrote:
On 13/02/2021 12:57, Pancho wrote:

Yes, I've had pretty LED table lamps run hot and fail, but I can't see
any reason a ceiling downlight wouldn't be well ventilated, many were
designed to handle halogen bulbs.


But not to provide any cooling for the bulb. The fitting is designed to
run hot as can be seen with ceramic bulb fitting (rather than plastic)


Halogens give out 10 times as much heat. They need to have cooling for
the bulb. Sure the equilibrium temperature for a 50W halogen may be much
greater than a 5W LED would tolerate. But the equilibrium temperature
for a 5W bulb will be much, much lower. I will leave one on for a couple
of hours and measure the temp.

To put things into perspective a friend used halogen GU10s and was
constantly having to replace them. She switched to LED four years ago
and as far as I know none have blown. Even if they do go, they are so
cheap they would need to blow far more often than they do to annoy me. I
don't call an electrician to change a light bulb.

My suspicion is that early GU10 LED bulbs were unreliable, and
manufactures seized upon this to promote a product with a higher profit
margin, integral fittings. The comments you see from electricians etc,
that you see online are probably from people who have read the
propaganda rather than accumulated enough evidence to form a valid
opinion of their own.

But WTF do I know :-)

FWIW my early bedside lamp LEDs failed (not GU10), I leave one on 24hrs
a day, the more recent ones of similar design haven't.

Scott used his keyboard to write :
I have had a very low failure rate. As others have suggested, it
seems to depend on whether the bulb is sufficiently ventilated. As a
matter of interest, does anyone know whether LEDs situated outside
last for longer?

I have had two fail, in the same enclosed fitting and outside over
recent times. So much depends upon the ability for cooling air to cool
the electronics down. I have since modified the fitting so as to allow
some air flow.

I have none indoors which lack a good exposure to air flow and none
have failed indoors.

On 13/02/2021 12:17, Pancho wrote:

Look on the bright side at least you didn't by an integral LED downlight
(why would anyone???)

Just fitted 134 of them. Not my choice.

And not bad I only hit one joist when drilling them out.

--
Adam

On 13/02/2021 15:54, ARW wrote:
On 13/02/2021 12:17, Pancho wrote:

Look on the bright side at least you didn't by an integral LED
downlight (why would anyone???)

Just fitted 134 of them. Not my choice.

And not bad I only hit one joist when drilling them out.

Did you remove enough of the joist to make it fit? Was there much left?

In message , at 12:17:05 on Sat, 13 Feb
2021, Pancho remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).
So far, about 8 months later, four of the twelve have failed. They
start flickering for a few days, then go very dim. On about 12hrs a
day.
Contacted the supplier (Meridian) who wouldn't comment on how long
they were supposed to last [see below], but sent me two replacements.
The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.


Average doesn't mean minimum. I expect 25k hrs is average under ideal
conditions. Having 4 fail in under 3k hrs seems surprising, but maybe
not that surprising.

Why did they only send two replacements? If 4 failed in under 2 years
they should send 4.

I contacted them when three had blown (that was about a month ago), and
they sent me only two. (But I had a box of very similar LEDS anyway).
Since then one more has gone. I'll be reminding them about the
short-shipment when I next contact them.

FWIW I have about ordered about 30 GU10 LED in the last 2 years,
cheapest I could find, none have failed. At about £1.5 per bulb. I
wouldn't be that fussed if a few did go. Not Meridian bulbs.

Look on the bright side at least you didn't by an integral LED
downlight (why would anyone???)

I didn't [directly] buy (or even specify) anything. The builder's
subcontractor did.
--
Roland Perry

On 13/02/2021 12:17, Pancho wrote:

Look on the bright side at least you didn't by an integral LED downlight

I have used some of those...

(why would anyone???)

Because they were good fit for the application, and provided a lighting
pattern that was not easy to achieve via other means.

The enclosure was designed for the lamp which it contains, and the
method of installation (flush fitting in an insulated ceiling), so there
is no reason to expect premature failure from them.





--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

Hmm.

The so called rated life seems to be a lab. one, where they are kept cool.
In normal use, pie in the sky. Hence only a 2 year warranty.

--
*War does not determine who is right - only who is left.

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

In article , Dave Plowman (News)
wrote:
In article , Roland Perry
wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They
start flickering for a few days, then go very dim. On about 12hrs a
day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

Hmm.

The so called rated life seems to be a lab. one, where they are kept
cool. In normal use, pie in the sky.

Rather like electric car range

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on for
a few hours? That almost invariably will explain the shortened life.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics and
heat do not get on. It might be worth your while taking it apart to
check how it has failed (as I recall you are an electronics engineer).

My money is definitely on capacitors that don't any more. The other
common one I have seen is single point failure on one LED die in a
series string but that doesn't do the PSU flashing thing.

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

They are good for the rated hours if they are able to dissipate away
their waste heat but downlighters in ceilings tend not to be able to do
that.

The original insulated fireproof fittings intended for running very hot
quartz halogen downlighters are particularly bad for killing LED bulbs.


--
Regards,
Martin Brown

In message , at 14:29:18 on Sat, 13 Feb
2021, Martin Brown remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on for
a few hours? That almost invariably will explain the shortened life.

When I changed the 4th one the other day, the main part was OK but the
base stub was almost too hot to hold.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics
and heat do not get on. It might be worth your while taking it apart to
check how it has failed (as I recall you are an electronics engineer).

I'll do that (although it's more like mechanical engineering ;-)

My money is definitely on capacitors that don't any more. The other
common one I have seen is single point failure on one LED die in a
series string but that doesn't do the PSU flashing thing.

So far, about 8 months later, four of the twelve have failed. They
start flickering for a few days, then go very dim. On about 12hrs a
day.
Contacted the supplier (Meridian) who wouldn't comment on how long
they were supposed to last [see below], but sent me two replacements.
The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

They are good for the rated hours if they are able to dissipate away
their waste heat but downlighters in ceilings tend not to be able to do
that.

The original insulated fireproof fittings intended for running very hot
quartz halogen downlighters are particularly bad for killing LED bulbs.

I'll take a look at a fitting later, and report back.
--
Roland Perry

In message , at 06:41:12 on Sun, 14 Feb 2021,
Roland Perry remarked:
In message , at 14:29:18 on Sat, 13 Feb
2021, Martin Brown remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on
for a few hours? That almost invariably will explain the shortened life.

When I changed the 4th one the other day, the main part was OK but the
base stub was almost too hot to hold.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics
and heat do not get on. It might be worth your while taking it apart
to check how it has failed (as I recall you are an electronics engineer).

I'll do that (although it's more like mechanical engineering ;-)

Remarkably few components. Yes, there's an old-fashioned electrolytic
capacitor (4.7uF), plus the two-legged "red blob", four surface mount
resistors and one surface-mount ?transistor.

http://www.perry.co.uk/images/gu10.jpg

My money is definitely on capacitors that don't any more. The other
common one I have seen is single point failure on one LED die in a
series string but that doesn't do the PSU flashing thing.

So far, about 8 months later, four of the twelve have failed. They
start flickering for a few days, then go very dim. On about 12hrs a

Contacted the supplier (Meridian) who wouldn't comment on how long
they were supposed to last [see below], but sent me two replacements.
The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

They are good for the rated hours if they are able to dissipate away
their waste heat but downlighters in ceilings tend not to be able to
do that.

The original insulated fireproof fittings intended for running very
hot quartz halogen downlighters are particularly bad for killing LED
bulbs.

I'll take a look at a fitting later, and report back.

A dull metal cylinder about the size of a baked bean tin, with a few
very small holes at the top, but nothing at all to introduce any
convection currents either lower down, or around the LED itself.
--
Roland Perry

Roland Perry wrote:
In message , at 06:41:12 on Sun, 14 Feb 2021,
Roland Perry remarked:
In message , at 14:29:18 on Sat, 13 Feb
2021, Martin Brown remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on
for a few hours? That almost invariably will explain the shortened life.

When I changed the 4th one the other day, the main part was OK but the
base stub was almost too hot to hold.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics
and heat do not get on. It might be worth your while taking it apart
to check how it has failed (as I recall you are an electronics
engineer).

I'll do that (although it's more like mechanical engineering ;-)

Remarkably few components. Yes, there's an old-fashioned electrolytic
capacitor (4.7uF), plus the two-legged "red blob", four surface mount
resistors and one surface-mount ?transistor.

http://www.perry.co.uk/images/gu10.jpg

That might be a capacitor dropper. Capacitor droppers are
a potential solution on low wattage bulbs.

https://bobparadiso.files.wordpress....p_dropper2.png

More sophisticated ones are protected a bit against overvoltage.

But regular designs like that, they do not take kindly to
transients on AC supply. A brief transient can cause the
light to "flash" brightly in sympathy, and excess currents
in the LEDs, lead to their demise. I'm not sure what would
cause a "flickering fault" in such a setup - the main dropper
cap (polypropylene?) has most of the drop across it.

Paul

"Paul" wrote in message
...
Roland Perry wrote:
In message , at 06:41:12 on Sun, 14 Feb 2021,
Roland Perry remarked:
In message , at 14:29:18 on Sat, 13 Feb
2021, Martin Brown remarked:
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

Simple question is how warm are the bulbs when one has been left on for
a few hours? That almost invariably will explain the shortened life.

When I changed the 4th one the other day, the main part was OK but the
base stub was almost too hot to hold.

If it is too warm to touch then it is almost certainly drying out its
PSU capacitors which will result in premature failure. Electrolytics
and heat do not get on. It might be worth your while taking it apart to
check how it has failed (as I recall you are an electronics engineer).

I'll do that (although it's more like mechanical engineering ;-)

Remarkably few components. Yes, there's an old-fashioned electrolytic
capacitor (4.7uF), plus the two-legged "red blob", four surface mount
resistors and one surface-mount ?transistor.

http://www.perry.co.uk/images/gu10.jpg

That might be a capacitor dropper. Capacitor droppers are
a potential solution on low wattage bulbs.

https://bobparadiso.files.wordpress....p_dropper2.png

More sophisticated ones are protected a bit against overvoltage.

But regular designs like that, they do not take kindly to
transients on AC supply. A brief transient can cause the
light to "flash" brightly in sympathy, and excess currents
in the LEDs, lead to their demise.

But a regulated current should survive that fine.

I'm not sure what would cause a "flickering fault" in such a setup - the
main dropper cap (polypropylene?) has most of the drop across it.

Yeah,it would be interesting to measure one with that fault.

Paul

On 14/02/2021 17:36, Roland Perry wrote:

Remarkably few components. Yes, there's an old-fashioned electrolytic
capacitor (4.7uF), plus the two-legged "red blob", four surface mount
resistors and one surface-mount ?transistor.

http://www.perry.co.uk/images/gu10.jpg


Capacitor dropper (red blob), bridge rectifier (not transistor) ,
smoothing capacitor (4.7uF, rated at 105 degrees C) and resistors acting
as fuses, inrush current limiters and bleeds.


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

Hmm.

There are two failure modes:

1) LED die output drops to 70% of initial intensity.
This is the definition of "LED failure".
It is a drop in intensity, not an outright failure.
This is the 25000 hour number.

2) PSU output stops working. The SMPS in the base
of the bulb uses an electrolytic capacitor. It lasts
2000 hours at 105C, it lasts 60000 hours at shirt
sleeve conditions. Overheating the PSU is not part
of the reliability specification. There is an
assumption you did not "cook the product on purpose".

Thus, the GU10 bulb maker assumes you placed the bulb
in ordinary room air, where convection keeps the bulb
at some ridiculously low temperature. That solves the
[2] problem.

Then we write the number from [1] "on the tin",
as the reliability number.

A "flickering failure" is not an expected failure mode.
It might mean the PSU is cooked.

*******

Here is a bulb take-apart.

https://kuzyatech.com/no-name-gu10-led-lamp-teardown

U1 is this thing.

https://web.archive.org/web/20110108...tny263_268.pdf

Notice, it has a pretty substantial heatsink
and a lot of attention to thermals.

The black can with the two wire legs, is the electrolytic capacitor.

Paul

In message , at 12:33:21 on Sat, 13 Feb
2021, Paul remarked:
Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).
So far, about 8 months later, four of the twelve have failed. They
start flickering for a few days, then go very dim. On about 12hrs a
day.
Contacted the supplier (Meridian) who wouldn't comment on how long
they were supposed to last [see below], but sent me two replacements.
The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.
Hmm.

There are two failure modes:

1) LED die output drops to 70% of initial intensity.
This is the definition of "LED failure".
It is a drop in intensity, not an outright failure.
This is the 25000 hour number.

2) PSU output stops working. The SMPS in the base
of the bulb uses an electrolytic capacitor. It lasts
2000 hours at 105C, it lasts 60000 hours at shirt
sleeve conditions. Overheating the PSU is not part
of the reliability specification. There is an
assumption you did not "cook the product on purpose".

Thus, the GU10 bulb maker assumes you placed the bulb
in ordinary room air, where convection keeps the bulb
at some ridiculously low temperature. That solves the
[2] problem.

Then we write the number from [1] "on the tin",
as the reliability number.

A "flickering failure" is not an expected failure mode.
It might mean the PSU is cooked.

What happens is the light starts by blinking off just long enough to be
noticeable as a flicker about once even ten seconds. After about a week
the rate increases until it's flickering constantly. One of them then
went into "steady, but only 10% light output" mode.

*******

Here is a bulb take-apart.

https://kuzyatech.com/no-name-gu10-led-lamp-teardown

U1 is this thing.

https://web.archive.org/web/20110108...owerint.com/si
tes/default/files/product-docs/tny263_268.pdf

Notice, it has a pretty substantial heatsink
and a lot of attention to thermals.

The black can with the two wire legs, is the electrolytic capacitor.

Paul

--
Roland Perry

On 14/02/2021 06:48, Roland Perry wrote:
In message , at 12:33:21 on Sat, 13 Feb
2021, Paul remarked:

Thus, the GU10 bulb maker assumes you placed the bulb
in ordinary room air, where convection keeps the bulb
at some ridiculously low temperature. That solves the
[2] problem.

Then we write the number from [1] "on the tin",
as the reliability number.

A "flickering failure" is not an expected failure mode.
It might mean the PSU is cooked.

What happens is the light starts by blinking off just long enough to be
noticeable as a flicker about once even ten seconds. After about a week
the rate increases until it's flickering constantly. One of them then
went into "steady, but only 10% light output" mode.

I have seen quite a few LED street lamps in the flickering mode and they
are probably no older than two years. I can't see why they should be so
unreliable after all the engineers have complete control of the thermal
environment and heatsinking. However, they do seem to fail quite often.

By comparison most of my domestic LED bulbs even the ones in old
spotlight fittings seem to survive remarkably well. Airflow is everything.

The fitting that kills LED bulbs most effectively is a hangs down from
the ceiling full globe type diffuser with no way out for the warm air.


--
Regards,
Martin Brown

In article ,
Martin Brown wrote:
On 14/02/2021 06:48, Roland Perry wrote:
In message , at 12:33:21 on Sat, 13 Feb
2021, Paul remarked:

Thus, the GU10 bulb maker assumes you placed the bulb
in ordinary room air, where convection keeps the bulb
at some ridiculously low temperature. That solves the
[2] problem.

Then we write the number from [1] "on the tin",
as the reliability number.

A "flickering failure" is not an expected failure mode.
It might mean the PSU is cooked.

What happens is the light starts by blinking off just long enough to be
noticeable as a flicker about once even ten seconds. After about a week
the rate increases until it's flickering constantly. One of them then
went into "steady, but only 10% light output" mode.

I have seen quite a few LED street lamps in the flickering mode and they
are probably no older than two years. I can't see why they should be so
unreliable after all the engineers have complete control of the thermal
environment and heatsinking. However, they do seem to fail quite often.

But purchasing departments tend to over-ride such issues.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the
builder's subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average
life" of 25k hrs.

Hmm.

Bought 15 similar ones 6 years ago for the kitchen. Got them from eBay -
pretty much the cheapest that i could find.

Not a single one has been replaced yet...

Do these devices run on transformers or are they mains with internal psus.
I'm out of touch since the halogen days. I think I'd be having a look inside
one to see how it works.
Brian

--

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

Blind user, so no pictures please
Note this Signature is meaningless.!
"JoeJoe" wrote in message
o.uk...
On 13/02/2021 11:29, Roland Perry wrote:
I've got GU10 LED downlighters in my extension, supplied by the builder's
subcontractor (so a bit arm's length).

So far, about 8 months later, four of the twelve have failed. They start
flickering for a few days, then go very dim. On about 12hrs a day.

Contacted the supplier (Meridian) who wouldn't comment on how long they
were supposed to last [see below], but sent me two replacements.

The box says "2yrs Guarantee", which is 34hrs a day at the "average life"
of 25k hrs.

Hmm.

Bought 15 similar ones 6 years ago for the kitchen. Got them from eBay -
pretty much the cheapest that i could find.

Not a single one has been replaced yet...