Currently have 9 mains voltage GU10 50W tungsten downlighters arrayed in a
bank of 3 x 3.
Each bank separately switched, for good reason.
Mains voltage tungsten is a PITA, changing lamps every five minutes,
tripping mcb on lamp failure etc.

The plan is to convert these to LV GU10, 12 volt.
Three 50w lamps @ 240v = C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum.
There is plenty of space to recable with 1.5mm or even 2.5mm t+e.
Dimming not required.

Would I be better off with wire-wound or electronic transformers?
I would have thought wire-wound but would appreciate some advice.
Also, any recommendation for decent/long-lived transformers ?
Thank you,

Nick.

On May 29, 4:45*pm, "Nick" wrote:
Currently have 9 mains voltage GU10 *50W tungsten downlighters arrayed in a
bank of 3 x 3.
Each bank separately switched, for good reason.
Mains voltage tungsten is a PITA, changing lamps every five minutes,
tripping mcb on lamp failure etc.

The plan is to convert these to LV GU10, 12 volt.
Three 50w lamps @ 240v = C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum.
There is plenty of space to recable with 1.5mm or even 2.5mm t+e.
Dimming not required.

Would I be better off with wire-wound or electronic transformers?
I would have thought wire-wound but would appreciate some advice.
Also, any recommendation for decent/long-lived transformers ?
Thank you,

Nick.

Electronic are cheap. Wirewound are very reliable.

http://wiki.diyfaq.org.uk/index.php?...e#Voltage_Drop
http://wiki.diyfaq.org.uk/index.php?title=Halogen


NT

On Sun, 29 May 2011 16:45:58 +0100, Nick wrote:

Currently have 9 mains voltage GU10 50W tungsten downlighters arrayed
in a bank of 3 x 3.
Each bank separately switched, for good reason. Mains voltage tungsten
is a PITA, changing lamps every five minutes, tripping mcb on lamp
failure etc.

The plan is to convert these to LV GU10, 12 volt. Three 50w lamps @ 240v
= C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum. There is plenty of
space to recable with 1.5mm or even 2.5mm t+e. Dimming not required.

Would I be better off with wire-wound or electronic transformers? I
would have thought wire-wound but would appreciate some advice. Also,
any recommendation for decent/long-lived transformers ? Thank you,

Nick.


Electronic transformers have a couple of advantages.
They are much lighter - easier when you are working from a pair of steps!
They often incorporate soft-start to increase the life of your lamps.
Many of them are dimmable using ordinary dimmers, without needing to
derate.

OTOH they are always something else to go wrong.

Wound transformers are heavy, sometimes Very *Heavy* indeed!
You need either special dimmers or much derated ones.
They can have a hefty switch-on surge, which doesn't help switch contacts.
They are probably as reliable as you can get.

You pays your money and takes your choice. I personally would recommend
dimmable electronic ones and make sure that you leave access to them. It
gives the option of adding dimmers later and the cost difference isn't
much. Try to mount them so that the secondary wiring is as short as
possible, no matter what you decide on.

IIRC when I did my kitchen I put 3 dimmable units in. 2 were fed from the
same dimmer and had 4 lamps each. The third (lower rating) had it's own
dimmer and just fed 2 lights over a breakfast bar.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info
Filtering everything posted from googlegroups to kill spam.

On May 29, 4:45*pm, "Nick" wrote:
Currently have 9 mains voltage GU10 *50W tungsten downlighters arrayed in a
bank of 3 x 3.
Each bank separately switched, for good reason.
Mains voltage tungsten is a PITA, changing lamps every five minutes,
tripping mcb on lamp failure etc.

The plan is to convert these to LV GU10, 12 volt.
Three 50w lamps @ 240v = C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum.
There is plenty of space to recable with 1.5mm or even 2.5mm t+e.
Dimming not required.

Would I be better off with wire-wound or electronic transformers?
I would have thought wire-wound but would appreciate some advice.
Also, any recommendation for decent/long-lived transformers ?
Thank you,

Nick.

Additionally to above, wire wound transformers are less efficient.

On May 29, 4:45*pm, "Nick" wrote:
Currently have 9 mains voltage GU10 *50W tungsten downlighters arrayed in a
bank of 3 x 3.
Each bank separately switched, for good reason.
Mains voltage tungsten is a PITA, changing lamps every five minutes,
tripping mcb on lamp failure etc.

The plan is to convert these to LV GU10, 12 volt.
Three 50w lamps @ 240v = C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum.
There is plenty of space to recable with 1.5mm or even 2.5mm t+e.
Dimming not required.

Would I be better off with wire-wound or electronic transformers?
I would have thought wire-wound but would appreciate some advice.
Also, any recommendation for decent/long-lived transformers ?
Thank you,

Nick.

Wirewound need held on their loading, torrodials especially have
terrible regulation, lose a lamp and voltage to rset rises.
Only tend to use them for open suspended cable sytems where
electronics would either not work or use the cables as aerials.

Mode and IBL make excellent electronic transformers.

Cheers
Adam

On 29/05/2011 16:45, Nick wrote:
Currently have 9 mains voltage GU10 50W tungsten downlighters arrayed in a
bank of 3 x 3.
Each bank separately switched, for good reason.
Mains voltage tungsten is a PITA, changing lamps every five minutes,
tripping mcb on lamp failure etc.

The plan is to convert these to LV GU10, 12 volt.
Three 50w lamps @ 240v = C 1.6A.
Three 50w lamps @ 12v = C 12.5A
Distance from transformers to lamps 2.0m maximum.
There is plenty of space to recable with 1.5mm or even 2.5mm t+e.
Dimming not required.

Would I be better off with wire-wound or electronic transformers?
I would have thought wire-wound but would appreciate some advice.
Also, any recommendation for decent/long-lived transformers ?
Thank you,

Nick.



In my lounge, I've got 3 arrays of 4 x 50w lamps, each driven off a 200w
electronic transformer from Screwfix. I've only had one transformer fail
in about 9 years (only to find that it wasn't as accessible as I thought
it was - and I had to remove some floorboards above it to get at it!)

In my kitchen - which was done more recently (about 2 years ago) I've
got 8 x 50w lamps, each with its own individual built-in transformer.
These are readily accessible by pulling the whole lot through the hole
in the ceiling - and don't give a single point of failure. In other
words, if a transformer fails (which it hasn't, yet) you lose only one lamp.

I would definitely adopt this (second) approach in future - and it makes
sense when replacing mains lamps because you don't have to modify the
wiring.
--
Cheers,
Roger
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On 30/05/2011 05:18, John Rumm wrote:


I usually find that electronic transformers (at least upto 250W power
handling) can usually be pushed through the hole of a standard
downlighter making replacement fairly simple even if you have one
transformer feeding several lamps.



Yes, but I then went and screwed the bloody thing to a joist (to support
it while the ceiling was nailed up) and then found that I couldn't reach
in far enough through the hole to unscrew it when it failed 9 years
later! g

In the event, the replacement transformer was different from the
original in that it had 4 sets of output terminals - with a current
limit on each - whereas the original had a single 200w output to which 4
lamps were connected via a junction box. So I did away with the junction
box and connected the individual lamps direct to the transformer. This
would have been difficult or impossible to do through a hole in the ceiling.

I'm a convert to individual transformers - for new work as well as
retro-fits!
--
Cheers,
Roger
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