Friend has a 4-lamp ceiling light which takes the usual GU10 halogen bulbs,
2 of them blew so she went out and bought 2 replacements which were LED
ones - same shape and fittings but have what looks like 3 LED lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights went
off after about 15 minutes, stayed off for about 10 minutes then came back
on - the "normal" bulbs stayed lit throughout. The LEDs also made a buzzing
noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or is
it not clever to have 2 LED and 2 halogen in the same fitting?

On Thu, 20 Dec 2012 13:33:42 +0000, Mentalguy2k8 wrote:

Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

Are the LED bulbs dimmer-compatible ? I noticed (in Sainsburys !) a few
weeks ago that theirs had "suitable for use with dimmers" on the box,
which implies there are some which aren't.

On 20/12/2012 13:33, Mentalguy2k8 wrote:
Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

I've got a fitting which has a mixture of halogen and LEDs and that
works ok - but it's not on a dimmer, so they're all fed with full mains
voltage.

I would have thought that, assuming the LEDs are suitable for dimming
(which they may not be), you would have wanted to use *all* LEDs rather
than a mixture. Otherwise you might expect odd things to happen because
the light output vs voltage for the two types is very likely not the same.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

"Tim Streater" wrote in message
...
In article ,
Jethro_uk wrote:

On Thu, 20 Dec 2012 13:33:42 +0000, Mentalguy2k8 wrote:

Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement?
Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

Are the LED bulbs dimmer-compatible ? I noticed (in Sainsburys !) a few
weeks ago that theirs had "suitable for use with dimmers" on the box,
which implies there are some which aren't.

Thass right, some don't work with dimmers. OP needs to check that.

I didn't see the packaging, I just got asked to fit them because she
couldn't put them in the holders.

They seemed to dim down OK when I turned the dimmer knob, it was with max
voltage (?) that they cut out after about 15 mins. I assumed that the dimmer
turned right up would be roughly the same as the lights being on via a
normal on/off switch. They did seem twice as bright as the existing lamps,
is it possible that they are designed to run off a lower voltage from a
transformer?

I'll see if she's still got the packaging.

"Roger Mills" wrote in message
...
On 20/12/2012 13:33, Mentalguy2k8 wrote:
Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

I've got a fitting which has a mixture of halogen and LEDs and that works
ok - but it's not on a dimmer, so they're all fed with full mains voltage.

I would have thought that, assuming the LEDs are suitable for dimming
(which they may not be), you would have wanted to use *all* LEDs rather
than a mixture. Otherwise you might expect odd things to happen because
the light output vs voltage for the two types is very likely not the same.

That would have been ideal, but I was asked what bulbs she should get and I
just said "normal GU10s" and she managed to find LED ones somewhere. I
assumed they were all halogen types in the shops.

"Tim Streater" wrote in message
...
In article ,
"Mentalguy2k8" wrote:

They seemed to dim down OK when I turned the dimmer knob, it was with max
voltage (?) that they cut out after about 15 mins. I assumed that the
dimmer turned right up would be roughly the same as the lights being on
via a normal on/off switch. They did seem twice as bright as the existing
lamps, is it possible that they are designed to run off a lower voltage
from a transformer?

No, GU10s run at mains voltage. Wouldn't be a GU10, would it, otherwise?

No idea, I was just asked to put them in the holes.

"Tim Streater" wrote in message
...
In article ,
"Mentalguy2k8" wrote:

"Roger Mills" wrote in message
...
On 20/12/2012 13:33, Mentalguy2k8 wrote:
Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement?
Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

I've got a fitting which has a mixture of halogen and LEDs and that
works ok - but it's not on a dimmer, so they're all fed with full mains
voltage.

I would have thought that, assuming the LEDs are suitable for dimming
(which they may not be), you would have wanted to use *all* LEDs rather
than a mixture. Otherwise you might expect odd things to happen because
the light output vs voltage for the two types is very likely not the
same.

That would have been ideal, but I was asked what bulbs she should get and
I just said "normal GU10s" and she managed to find LED ones somewhere. I
assumed they were all halogen types in the shops.

There's plenty of LED ones in the shops. I got four from B&Q but then
SWMBO pointed out that they had a spread of only 35deg, so I got some
120deg ones from:

https://www.wholesaleledlights.co.uk/

--
Tim

"That excessive bail ought not to be required, nor excessive fines
imposed,
nor cruel and unusual punishments inflicted" -- Bill of Rights 1689

That site has dimmable LED GU10s - a different category to the main lot..

Mentalguy2k8 wrote:

Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which were
LED ones - same shape and fittings but have what looks like 3 LED lamps
inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights went
off after about 15 minutes, stayed off for about 10 minutes then came back
on - the "normal" bulbs stayed lit throughout. The LEDs also made a
buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

The LEDs must be marked as "Dimmable".

It's not that intuitive as most of us are used to LEDs having simple
resistors as current limiters - and these would be fine on any dimmer.

However, the high power LEDs have active current limiters (in effect little
internal "dimmers") and it is this which does not like being fed by a dimmer
- unless it has been designed for it.

As for halogens and LEDs in the same feed - that's fine. In fact it would be
a good thing if the LEDs alone might not provide enough load for the dimmer.

--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"It would be better to live under robber barons than under omnipotent
moral busybodies."

Jethro_uk wrote:

On Thu, 20 Dec 2012 13:33:42 +0000, Mentalguy2k8 wrote:

Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which
were LED ones - same shape and fittings but have what looks like 3 LED
lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights
went off after about 15 minutes, stayed off for about 10 minutes then
came back on - the "normal" bulbs stayed lit throughout. The LEDs also
made a buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

Are the LED bulbs dimmer-compatible ? I noticed (in Sainsburys !) a few
weeks ago that theirs had "suitable for use with dimmers" on the box,
which implies there are some which aren't.

Most aren't. Like CFLs and for much the same reason - they are full of
electronics :-(

If they don;t say "dimmable", they aren't.
--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"History will be kind to me for I intend to write it."

Tim Streater wrote:

In article ,
"Mentalguy2k8" wrote:

They seemed to dim down OK when I turned the dimmer knob, it was with max
voltage (?) that they cut out after about 15 mins. I assumed that the
dimmer turned right up would be roughly the same as the lights being on
via a normal on/off switch. They did seem twice as bright as the existing
lamps, is it possible that they are designed to run off a lower voltage
from a transformer?

No, GU10s run at mains voltage. Wouldn't be a GU10, would it, otherwise?


Yes - that is the case.

You can get G4 LED bulbs if a 12V supply is desired (eg for safety reasons).
--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"She got her looks from her father. He's a plastic surgeon."

On Thu, 20 Dec 2012 13:33:42 -0000, "Mentalguy2k8"
wrote:

Friend has a 4-lamp ceiling light which takes the usual GU10 halogen bulbs,
2 of them blew so she went out and bought 2 replacements which were LED
ones - same shape and fittings but have what looks like 3 LED lamps inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights went
off after about 15 minutes, stayed off for about 10 minutes then came back
on - the "normal" bulbs stayed lit throughout. The LEDs also made a buzzing
noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or is
it not clever to have 2 LED and 2 halogen in the same fitting?

In light of my thread up there ^^^^^^^^^
I've been looking at recommended dimmers - some LEDs need leading edge
and some trailing edge.
This page explains why, and the pitfalls...
http://sound.westhost.com/lamps/dimmers.html
I don't suppose it's totally comprehensive and there's bound to be
someone who knows a bit more who can come along and illucidate
further.

I strongly suspect theleds have a switch mode psu, which is not working
correctly on a dimmer.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Mentalguy2k8" wrote in message
...
Friend has a 4-lamp ceiling light which takes the usual GU10 halogen
bulbs, 2 of them blew so she went out and bought 2 replacements which were
LED ones - same shape and fittings but have what looks like 3 LED lamps
inside.

They're all fed via a dimmer switch directly from light circuit (no
transformer), and with the dimmer turned up to max, the 2 LED lights went
off after about 15 minutes, stayed off for about 10 minutes then came back
on - the "normal" bulbs stayed lit throughout. The LEDs also made a
buzzing noise with the dimmer turned down.

Are they overheating or just not suitable to use in this arrangement? Or
is it not clever to have 2 LED and 2 halogen in the same fitting?

On 20/12/2012 15:18, Mentalguy2k8 wrote:

"Tim Streater" wrote in message
...
In article ,
"Mentalguy2k8" wrote:

They seemed to dim down OK when I turned the dimmer knob, it was with
max voltage (?) that they cut out after about 15 mins. I assumed that
the dimmer turned right up would be roughly the same as the lights
being on via a normal on/off switch. They did seem twice as bright as
the existing lamps, is it possible that they are designed to run off
a lower voltage from a transformer?

No, GU10s run at mains voltage. Wouldn't be a GU10, would it, otherwise?

No idea, I was just asked to put them in the holes.

Did you have to push & twist or just push?

--
Dave - The Medway Handyman www.medwayhandyman.co.uk

Tim Streater wrote:
In article ,
"Mentalguy2k8" wrote:

They seemed to dim down OK when I turned the dimmer knob, it was
with max voltage (?) that they cut out after about 15 mins. I
assumed that the dimmer turned right up would be roughly the same as
the lights being on via a normal on/off switch. They did seem twice
as bright as the existing lamps, is it possible that they are
designed to run off a lower voltage from a transformer?

No, GU10s run at mains voltage. Wouldn't be a GU10, would it,
otherwise?


Some American GU10.s are 220 volt

Tim Streater wrote:
In article ,
"Mentalguy2k8" wrote:

They seemed to dim down OK when I turned the dimmer knob, it was
with max voltage (?) that they cut out after about 15 mins. I
assumed that the dimmer turned right up would be roughly the same as
the lights being on via a normal on/off switch. They did seem twice
as bright as the existing lamps, is it possible that they are
designed to run off a lower voltage from a transformer?

No, GU10s run at mains voltage. Wouldn't be a GU10, would it,
otherwise?


Some American GU10.s are 220 volt