Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

Thanks.

MM

MM formulated on Thursday :
The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

A replacement 5w LED lamp would be below the 10-60va and even more so
the 20-60va lower limit. Having said that, I suppose you could buy one
and see how it goes, before spending more.

On 16/03/2017 14:06, MM wrote:
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

Assuming that the MR16 pin compatible LEDs you buy are designed to work
off a nominal 12v supply then it ought to work - although any in circuit
dimmer may baulk at the load not being sufficient to work properly. You
may need to connect 4 or 5 LED's in parallel across a single old
transformer to meet the transformers minimum load expectations (likewise
for any dimmer on the circuit).

The LEDs might also be subject to some over voltage if the tranformers
minimum load is not met (won't harm the transformer but might well
shorten the LED lifetime). I suspect this is the main failure mode of
some cheap LED refits in hotel corridors.

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

What makes you think they know what they are talking about?

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die. They also don't
like being fed AC if they have been designed for DC only operation.

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

Short answer is it depends. The downlighter market is now complete
madness with 240v, 12v ac and dc devices on offer so you really need to
read the spec sheet(s) for the specific choice of bulb or fixture
carefully. I think that MR16 LED bulbs claim to be pin compatible
replacements for 12v halogens should be OK but they will come in
dimmable and non-dimmable versions (the latter should be a bit cheaper).

Some are designed to be pin compatible with existing installations and
so will run off existing transformers others are intended for rip out
and replace entirely. The latter tend to work better longer term since
the thick insulation designed to protect a ceiling from the hot quartz
halogen bulb tends to shorten the lifetime of LED based devices.

--
Regards,
Martin Brown

In article ,
MM wrote:
So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

The problem here is you're not using a traditional transformer. But an
SMPS to do the same job. A traditional transformer will produce (roughly)
the same voltage with any lower load than maximum. A SMPS will usually
have both a minimum and maximum load. In your case 10 VA minimum, and a 5
watt LED should be approximately 5VA.

But try it and see. You may be lucky.

If the wiring is easy to get to, you could run two or more fittings off
the one SMPS.

BTW,a 5 watt LED isn't going to give the same light as a 50w halogen. More
like a 35w halogen.

You can get 50w equivalents, but they'll be 6.5w and cost about a tenner
each.

--
*Don't squat with your spurs on *

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

On Thu, 16 Mar 2017 14:45:46 +0000, Martin Brown
wrote:

On 16/03/2017 14:06, MM wrote:
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

Assuming that the MR16 pin compatible LEDs

They are these: http://tinyurl.com/jb6wech

you buy are designed to work
off a nominal 12v supply then it ought to work - although any in circuit
dimmer may baulk at the load not being sufficient to work properly.

No dimmers.

You
may need to connect 4 or 5 LED's in parallel across a single old
transformer to meet the transformers minimum load expectations (likewise
for any dimmer on the circuit).

The LEDs might also be subject to some over voltage if the tranformers
minimum load is not met (won't harm the transformer but might well
shorten the LED lifetime). I suspect this is the main failure mode of
some cheap LED refits in hotel corridors.

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

What makes you think they know what they are talking about?

They're selling LED bulbs and a potential customer asked a question.

Perhaps they just want to sell extra stuff whether it's needed or not.

Replacing just a bulb (halogen with LED) is relatively inexpensive,
but if I have to replace all the transformers as well, then we're
talking about a lot of money. There are 29 halogen downlighters in my
house.

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die. They also don't
like being fed AC if they have been designed for DC only operation.

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

Short answer is it depends. The downlighter market is now complete
madness with 240v, 12v ac and dc devices on offer so you really need to
read the spec sheet(s) for the specific choice of bulb or fixture
carefully. I think that MR16 LED bulbs claim to be pin compatible
replacements for 12v halogens should be OK but they will come in
dimmable and non-dimmable versions (the latter should be a bit cheaper).

Some are designed to be pin compatible with existing installations and
so will run off existing transformers others are intended for rip out
and replace entirely. The latter tend to work better longer term since
the thick insulation designed to protect a ceiling from the hot quartz
halogen bulb tends to shorten the lifetime of LED based devices.

If I bought one pack of the five on offer from Screwfix (URL above) to
try, would I

1. Damage the new LED bulb?
2. Damage the transformer?
3. Cause a potentially dangerous situation with the the rest of the
house wiring?
4. Cause overheating in the ceiling space to occur? Fire risk?

If the LEDs didn't work, either I could just forget about it, or
replace each downlighter with an LED and the proper LED driver (though
God knows what that would be) as and when the next halogen bulb blows.

Mind you, I've lived here in this house from new (12 years) and most
of the MR16 halogen bulbs are still the originals. They blow very
infrequently, mostly in the kitchen where the downlighting is often
on, especially in the winter months.

MM

On Thu, 16 Mar 2017 16:12:28 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
MM wrote:
So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

The problem here is you're not using a traditional transformer. But an
SMPS

SMPS?

to do the same job. A traditional transformer will produce (roughly)
the same voltage with any lower load than maximum. A SMPS will usually
have both a minimum and maximum load. In your case 10 VA minimum, and a 5
watt LED should be approximately 5VA.

But try it and see. You may be lucky.

If the wiring is easy to get to, you could run two or more fittings off
the one SMPS.

BTW,a 5 watt LED isn't going to give the same light as a 50w halogen. More
like a 35w halogen.

If anything, the current lighting is overbright anyway.

You can get 50w equivalents, but they'll be 6.5w and cost about a tenner
each.

On 16/03/2017 14:45, Martin Brown wrote:

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die.

Why? Assuming you are using the voltage the manufacturer specifies.


--
Adam

The problem is that there seems to be leds with constant current circuits
and some where its in the transformer psu and no doubt yet others that work
on the full mains.
I always smile at the way making things modern simply complicates things.
Brian

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

Blind user, so no pictures please!
"MM" wrote in message
...
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

Thanks.

MM

And of course if there was a constant current circuit in the lamp it would
not play nice with a dimmer.
Brian

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

Blind user, so no pictures please!
"Harry Bloomfield" wrote in message
news
MM formulated on Thursday :
The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

A replacement 5w LED lamp would be below the 10-60va and even more so the
20-60va lower limit. Having said that, I suppose you could buy one and see
how it goes, before spending more.

ARW has brought this to us :
On 16/03/2017 14:45, Martin Brown wrote:

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die.

Why? Assuming you are using the voltage the manufacturer specifies.

Current limiting should be within the LED lamp anyway.

MM brought next idea :
SMPS?

Switch Mode Power Supply.

Rather than a simple transformer, a more efficient method is to use a
SMPS, which controls the voltage supplied at the output, by rapidly
switching on and off, then filtering the output. Most easily they
produce a fixed DC voltage.

On 16/03/2017 17:56, ARW wrote:
On 16/03/2017 14:45, Martin Brown wrote:

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die.

Why? Assuming you are using the voltage the manufacturer specifies.

Bare LEDs are current driven devices. You can get away with driving them
without current limiting for small power levels but when you want
serious light output they have to be protected somehow.

Their semiconducting resistance decreases as they get hotter and on an
insufficient heatsink they will fail by thermal runaway when driven at
constant voltage if they ever get a bit too warm.

http://www.luxdrive.com/products/wha...ermal-runaway/

It really is very bad practice to drive them hard at constant voltage.

--
Regards,
Martin Brown

On 16/03/2017 18:26, Martin Brown wrote:
On 16/03/2017 17:56, ARW wrote:
On 16/03/2017 14:45, Martin Brown wrote:

A constant voltage driver is potentially death for LEDs. They need to be
operated in a current limited mode or they will die.

Why? Assuming you are using the voltage the manufacturer specifies.

Bare LEDs are current driven devices. You can get away with driving them
without current limiting for small power levels but when you want
serious light output they have to be protected somehow.

Their semiconducting resistance decreases as they get hotter and on an
insufficient heatsink they will fail by thermal runaway when driven at
constant voltage if they ever get a bit too warm.

http://www.luxdrive.com/products/wha...ermal-runaway/

It really is very bad practice to drive them hard at constant voltage.

Would you use a constant current driver on the lamps the OP has suggested?

--
Adam

In article ,
MM writes:
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

The LEDs will be too low power for the electronic transformers
to stay on - typically they'll flash on and off in this situation.

I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

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

On 16/03/2017 20:45, Andrew Gabriel wrote:
In article ,
MM writes:
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

The LEDs will be too low power for the electronic transformers
to stay on - typically they'll flash on and off in this situation.

I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

Are they what I call GU10's?

--
Adam

On Thu, 16 Mar 2017 21:53:16 +0000, ARW wrote:

I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

Are they what I call GU10's?

Thank you!
I've just been looking for GU50, having never seen that before. I should
have read your post first.
--
Peter.
The gods will stay away
whilst religions hold sway

In article ,
ARW writes:
On 16/03/2017 20:45, Andrew Gabriel wrote:
In article ,
MM writes:
Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace
these with LED equivalents.

Each halogen bulb at present is connected to its own transformer,
which is in turn connected to the mains. The transformer is a JC4030
10-60VA electronic transformer Auto-Reset Dimmable (reading off an
empty box) or equivalent. I've also used Knightsbridge IP20 Electronic
Dimmable Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light
equivalent to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question:
"Does this mean that I must remove the transformers from all of the
fittings (21 of them throughout the house) currently in place with the
12v halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place
and simply swap out the halogen for the LED?

The LEDs will be too low power for the electronic transformers
to stay on - typically they'll flash on and off in this situation.

I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

Are they what I call GU10's?

Yes!

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

On 16/03/2017 20:01, ARW wrote:
On 16/03/2017 18:26, Martin Brown wrote:
On 16/03/2017 17:56, ARW wrote:
On 16/03/2017 14:45, Martin Brown wrote:

A constant voltage driver is potentially death for LEDs. They need
to be
operated in a current limited mode or they will die.

Why? Assuming you are using the voltage the manufacturer specifies.

Bare LEDs are current driven devices. You can get away with driving them
without current limiting for small power levels but when you want
serious light output they have to be protected somehow.

Their semiconducting resistance decreases as they get hotter and on an
insufficient heatsink they will fail by thermal runaway when driven at
constant voltage if they ever get a bit too warm.

http://www.luxdrive.com/products/wha...ermal-runaway/

It really is very bad practice to drive them hard at constant voltage.

Would you use a constant current driver on the lamps the OP has suggested?

I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

It is likely that the consumer use bulbs are intended to be pin
compatible with 12v halogen bulbs but using a lot less power. They might
well be OK on any sort of PSU that yields roughly 12v ac or dc provided
that the minimum load requirements of the PSU are satisfied.

--
Regards,
Martin Brown

Andrew Gabriel explained on 17/03/2017 :
Yes!

Aldi had a stock of GU10's in the last two weeks, 5w for around £9 per
box of 10 and marked 240v.

In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.

--
*I don't work here. I'm a consultant

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

In article ,
Andrew Gabriel wrote:
I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

Low voltage types usually have tails. Can you get similar tails for GU50?
To avoid having to change the fitting?

--
*A backward poet writes inverse.*

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

In article ,
"Dave Plowman (News)" writes:
In article ,
Andrew Gabriel wrote:
I would suggest changing the fittings to GU50 (mains) ones which
don't use transformers, and use GU50 LEDs. There's a much better
range of GU50 mains LEDs available than MR16 12V LED replacements.

Low voltage types usually have tails. Can you get similar tails for GU50?
To avoid having to change the fitting?

A search for 'GU10 lampholder' returned loads.

This is only suitable if your existing MR16 fittings hold the lamps
in place using the front ring and use a flying socket, rather than
just gripping the lamp in a fixed socket.

Using fittings which grip the lamp by the front ring does allow the
use of longer higher power lamps, which would otherwise stick out
too far if used in GU10 fittings with a fixed lampholder.

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

In article ,
Andrew Gabriel wrote:
Low voltage types usually have tails. Can you get similar tails for GU50?
To avoid having to change the fitting?

A search for 'GU10 lampholder' returned loads.

This is only suitable if your existing MR16 fittings hold the lamps
in place using the front ring and use a flying socket, rather than
just gripping the lamp in a fixed socket.

Yes. All of mine have a ring to hold the lamp in place. And some are
mains, some low volts. But dunno what is around today.

Using fittings which grip the lamp by the front ring does allow the
use of longer higher power lamps, which would otherwise stick out
too far if used in GU10 fittings with a fixed lampholder.

--
*You never really learn to swear until you learn to drive *

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

On Thu, 16 Mar 2017 14:06:52 +0000, MM wrote:

Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace these
with LED equivalents.

Each halogen bulb at present is connected to its own transformer, which
is in turn connected to the mains. The transformer is a JC4030 10-60VA
electronic transformer Auto-Reset Dimmable (reading off an empty box) or
equivalent. I've also used Knightsbridge IP20 Electronic Dimmable
Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light equivalent
to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question: "Does
this mean that I must remove the transformers from all of the fittings
(21 of them throughout the house) currently in place with the 12v
halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place and
simply swap out the halogen for the LED?

Thanks.

MM


You can try just swapping them out, but you might find that they don't
work. You need to meet the minimum load requirement for an electronic
transformer to keep the output stable. However, if you can get the wiring
in place, you could run several MR16 LEDs from a single existing
transformer to meet the 20W minimum (35W if you want to feed the
transformer from a dimmer). Alternatively you could put one halogen and
several LEDs on a single transformer. That works well if you don't mind a
colour difference although you don't gain all the power savings.

All MR16 LEDs contain a bridge rectifier so it doesn't matter if the
supply to them from the transformer is AC or DC.

The advantage of a constant voltage transformer is that it's impossible
to overdrive your LEDs. The maximum output is usually just below 12V
(something like 11.8V) and it will stay like that even with mains
fluctuations. The MR16 LEDs are designed for this sort of supply and
contain their own current limiting.

Constant current supplies are used for direct drive LEDs which do not
contain current limiting (usually power LEDs). The LEDs (not the MR16
type) are connected in series.

On 17/03/2017 10:47, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.


Personally I would go for GU10 LED (remove all transformers and swap the
lamp holders), however if the OP wants to stick with MR 16 then I would
remove all the transformers apart from the first in line and buy a 12V
constant voltage driver to go there (similar to Martins idea)


--
Adam

On 17/03/2017 14:38, mick wrote:

Constant current supplies are used for direct drive LEDs which do not
contain current limiting (usually power LEDs). The LEDs (not the MR16
type) are connected in series.


You know that we are back to Xmas tree light failure situations when one
fails:-)

--
Adam

In article ,
ARW wrote:
The snag is that with many a ceiling light, getting at the wiring to
alter things may not be easy. A single SMPS per lamp is common so it
can be replaced if needed by just removing the fitting. If the wiring
was easy to get at, you'd use a SMPS for more than one lamp even with
halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.

But does that mean it would be easy to alter the wiring so one transformer
feeds several lights?


Personally I would go for GU10 LED (remove all transformers and swap the
lamp holders), however if the OP wants to stick with MR 16 then I would
remove all the transformers apart from the first in line and buy a 12V
constant voltage driver to go there (similar to Martins idea)

--
*Never miss a good chance to shut up *

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

On 17/03/2017 23:48, Dave Plowman (News) wrote:
In article ,
ARW wrote:
The snag is that with many a ceiling light, getting at the wiring to
alter things may not be easy. A single SMPS per lamp is common so it
can be replaced if needed by just removing the fitting. If the wiring
was easy to get at, you'd use a SMPS for more than one lamp even with
halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.

But does that mean it would be easy to alter the wiring so one transformer
feeds several lights?




It would be feeding all the lights


--
Adam

On Fri, 17 Mar 2017 10:47:43 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.

Yep, there's no way I could connect more than one downlighter to the
same SMPS. That would mean routing new cable through the ceiling space
for a number of downlighters. My halogen downlighters each have their
own electronic transformer (JC 4030 from JCC).

This is what I have now:
http://www.littletyke.myzen.co.uk/lights/index.html

(Shows previous transformer, since replaced with a JC 4030.)

MM

On Fri, 17 Mar 2017 18:51:22 +0000, ARW
wrote:

On 17/03/2017 10:47, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.


Personally I would go for GU10 LED (remove all transformers and swap the
lamp holders), however if the OP wants to stick with MR 16 then I would
remove all the transformers apart from the first in line and buy a 12V
constant voltage driver to go there (similar to Martins idea)

And route a rat's nest of new cables throughout the ceiling spaces?

MM

On Fri, 17 Mar 2017 23:48:01 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
ARW wrote:
The snag is that with many a ceiling light, getting at the wiring to
alter things may not be easy. A single SMPS per lamp is common so it
can be replaced if needed by just removing the fitting. If the wiring
was easy to get at, you'd use a SMPS for more than one lamp even with
halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.

But does that mean it would be easy to alter the wiring so one transformer
feeds several lights?

In my case, it would be anything but easy. I'd rather buy LED drivers
instead.

MM

On Sat, 18 Mar 2017 07:55:47 +0000, ARW
wrote:

On 17/03/2017 23:48, Dave Plowman (News) wrote:
In article ,
ARW wrote:
The snag is that with many a ceiling light, getting at the wiring to
alter things may not be easy. A single SMPS per lamp is common so it
can be replaced if needed by just removing the fitting. If the wiring
was easy to get at, you'd use a SMPS for more than one lamp even with
halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.

But does that mean it would be easy to alter the wiring so one transformer
feeds several lights?




It would be feeding all the lights

29 downlighters in total all over the house? Kitchen, annex, two
bathrooms, hall, landing...

MM

On 17 Mar 2017 14:38:58 GMT, mick wrote:

On Thu, 16 Mar 2017 14:06:52 +0000, MM wrote:

Currently I have lots of 50W MR16 halogen downlighters, but since the
latest exorbitant lecky price rise announcement I plan to replace these
with LED equivalents.

Each halogen bulb at present is connected to its own transformer, which
is in turn connected to the mains. The transformer is a JC4030 10-60VA
electronic transformer Auto-Reset Dimmable (reading off an empty box) or
equivalent. I've also used Knightsbridge IP20 Electronic Dimmable
Transformer for 12V Low Voltage Halogen Lamps 20-60VA

Converning replacement with LED, one website states:

"A room has 4 downlights using 50w Halogen bulbs each has its own
transformer all rated at 60VA. You could successfully replace the
Halogens with the Crompton 5w LED MR16 which gives out light equivalent
to the 50w Halogen bulb."

But on the Screwfix website, in answer to a customer's question: "Does
this mean that I must remove the transformers from all of the fittings
(21 of them throughout the house) currently in place with the 12v
halogens?"

their response is:

"If you are going to fit MR 16 Led Lamps you will have to change all
your transformers, the one you require would be either:
Halolite Led constant current driver 1-9W (66599).
Halolite Led constant voltage driver 1-16W (85503)."

So I'm confused. Can I leave all the existing transformers in place and
simply swap out the halogen for the LED?

Thanks.

MM


You can try just swapping them out, but you might find that they don't
work. You need to meet the minimum load requirement for an electronic
transformer to keep the output stable. However, if you can get the wiring
in place, you could run several MR16 LEDs from a single existing
transformer to meet the 20W minimum (35W if you want to feed the
transformer from a dimmer). Alternatively you could put one halogen and
several LEDs on a single transformer. That works well if you don't mind a
colour difference although you don't gain all the power savings.

All MR16 LEDs contain a bridge rectifier so it doesn't matter if the
supply to them from the transformer is AC or DC.

The advantage of a constant voltage transformer is that it's impossible
to overdrive your LEDs. The maximum output is usually just below 12V
(something like 11.8V) and it will stay like that even with mains
fluctuations. The MR16 LEDs are designed for this sort of supply and
contain their own current limiting.

Constant current supplies are used for direct drive LEDs which do not
contain current limiting (usually power LEDs). The LEDs (not the MR16
type) are connected in series.

This idea of mine now sounds like a complicated and potentially
expensive solution to try and save a bit of money.

I never wanted the ruddy downlighters after I'd lived here for a few
weeks. The lights are much too bright anyway and there are too many of
them. FOUR (count 'em!) in a bathroom barely large enough to swing a
cat in! When I signed on the dotted line I thought, well, the
downlighters are not my cup of tea, but surely it's a minor detail?

Well, I wouldn't have NOT bought the property just because of the
downlighters, but now that they are costing much more to run, thanks
to SSE's latest price hike to start in April, they are irritating my
natural sense of frugal living.

I grew up with pendant lights! One single light hanging down in the
centre of a room. Dark, dingy, but kind of cosy. Later, mum and dad
actually installed a few table lamps, too. Luxury! Suddenly we went
from working class to middle class with just a trip to Timothy Whites!

Now, when I switch on the kitchen lights, I look around for the MI5
interrogator, because they're bright enough to frighten Kim Jon-Un.

To be quite honest, I'd be better off removing or just disconnecting
all the halogens and connecting ceiling roses and pendant cables to
two of the brown junction boxes.
http://www.littletyke.myzen.co.uk/lights/index.html

Then I could pop a standard 240V LED bulb in each and be done with it.
http://www.screwfix.com/p/lap-gls-le...w-5-pack/8621j

I've got some of these bulbs for other rooms* and they work fine and
come on instantly.

A future owner could then decide what they want to do with the
lighting.

MM

* For some reason, the builder DIDN'T install downlighters in the
living room or the bedrooms! Go figure!

Those rooms all have bog-standard, single, pendant lights.

On 18/03/2017 09:21, MM wrote:
On Fri, 17 Mar 2017 18:51:22 +0000, ARW
wrote:

On 17/03/2017 10:47, Dave Plowman (News) wrote:
In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.


His wiring is easy to get to. He has posted photos of it before. Every
spot light has a small 20A JB connected to the transformer. All very
accessible by just pulling down all the spot lights.


Personally I would go for GU10 LED (remove all transformers and swap the
lamp holders), however if the OP wants to stick with MR 16 then I would
remove all the transformers apart from the first in line and buy a 12V
constant voltage driver to go there (similar to Martins idea)

And route a rat's nest of new cables throughout the ceiling spaces?



Not at all if you are prepared to listen and learn.


--
Adam

On 18/03/2017 09:18, MM wrote:
On Fri, 17 Mar 2017 10:47:43 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.

Yep, there's no way I could connect more than one downlighter to the
same SMPS. That would mean routing new cable through the ceiling space
for a number of downlighters. My halogen downlighters each have their
own electronic transformer (JC 4030 from JCC).

I disagree.




--
Adam

In article ,
MM wrote:
The snag is that with many a ceiling light, getting at the wiring to alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was easy to
get at, you'd use a SMPS for more than one lamp even with halogen.

Yep, there's no way I could connect more than one downlighter to the
same SMPS. That would mean routing new cable through the ceiling space
for a number of downlighters. My halogen downlighters each have their
own electronic transformer (JC 4030 from JCC).

This is what I have now:
http://www.littletyke.myzen.co.uk/lights/index.html

(Shows previous transformer, since replaced with a JC 4030.)

Unless you could get at the feed from the switch and use one unit for all?
Then just remove all the others?

Assuming a suspended ceiling, if might be possible to run in some new
wiring using the existing spot holes - depending on how the joists run.

But the easy way would be to just replace all the halogen 'transformers'
with LED ones. You might be able to sell the old ones on Ebay, to defray
the cost.

I had a very similar problem in my large bathroom. Was built with a new
ceiling and totally replastered. The original lights were all RO80
downlighters which I wanted to change for LV types some way down the line.
No chance of access from above as it's now a roof terrace. And didn't want
to replace the perfect ceiling. Also wanted some additional lights.

Did manage to do what I wanted - but a right fiddle, compared to starting
afresh.

I've no interest in changing the LV halogens to LED, though, given the
bathroom lights aren't on for a vast time.

--
*You can't teach an old mouse new clicks *

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

On 18/03/17 10:43, ARW wrote:
On 18/03/2017 09:18, MM wrote:
On Fri, 17 Mar 2017 10:47:43 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Martin Brown wrote:
I'd probably use whatever is already there but with 4 or 5 lamps
connected to each transformer rather than a transformer per lamp.
(making a note somewhere that going back to halogens isn't possible)

The snag is that with many a ceiling light, getting at the wiring to
alter
things may not be easy. A single SMPS per lamp is common so it can be
replaced if needed by just removing the fitting. If the wiring was
easy to
get at, you'd use a SMPS for more than one lamp even with halogen.

Yep, there's no way I could connect more than one downlighter to the
same SMPS. That would mean routing new cable through the ceiling space
for a number of downlighters. My halogen downlighters each have their
own electronic transformer (JC 4030 from JCC).

I disagree.




I've done it both ways.

Its detail dependent. No 'right' way for all cases.


--
Canada is all right really, though not for the whole weekend.

"Saki"

MM wrote:

This idea of mine now sounds like a complicated and potentially
expensive solution to try and save a bit of money.

I never wanted the ruddy downlighters after I'd lived here for a few
weeks. The lights are much too bright anyway and there are too many of
them.

You could look around for lower rated halogens, which should save
a bit of energy and reduce the brightness.

Chris
--
Chris J Dixon Nottingham UK


Plant amazing Acers.

On Mon, 20 Mar 2017 07:27:38 +0000, Chris J Dixon
wrote:

MM wrote:

This idea of mine now sounds like a complicated and potentially
expensive solution to try and save a bit of money.

I never wanted the ruddy downlighters after I'd lived here for a few
weeks. The lights are much too bright anyway and there are too many of
them.

You could look around for lower rated halogens, which should save
a bit of energy and reduce the brightness.

Chris

Yes, I do that already when one of the 50W ones blows. I replace it
with a 35W. But so far I've only ever had to replace about 7 bulbs in
12 years! And about 4 transformers.

Maybe I should use the microwave more for cooking, as I do tend to
have the oven and/or grill on quite a lot. I expect if I only ate
ready meals from the chiller cabinet and did hardly any cooking at
all, my electricity bill would show a marked fall after a year.

MM