Hi
I am installing a set of 3 low voltage halogen lights in my kitchen ceiling,
however I find that the lead between light 1 and 2 is too short for my
purpose.

I have read that the wiring rating on this side of the transformer needs to
be substantial especially if its any length.

What gauge wire do I need to extend it to two metres?


Thanks
Roger

"Roger" wrote in message
...
Hi
I am installing a set of 3 low voltage halogen lights in my kitchen
ceiling,
however I find that the lead between light 1 and 2 is too short for my
purpose.

I have read that the wiring rating on this side of the transformer needs
to
be substantial especially if its any length.

What gauge wire do I need to extend it to two metres?


Thanks
Roger



A 1 mm csa' (cross sectional area) is enough for a 2 mtr length.

On Wed, 22 Dec 2004 21:14:48 GMT, "BigWallop"
wrote:

[snip]

A 1 mm csa' (cross sectional area) is enough for a 2 mtr length.

Would 1mm T+E be enough for several metres?


Replace 'spam' with 'org' to reply

"Kalico" wrote in message
...
On Wed, 22 Dec 2004 21:14:48 GMT, "BigWallop"
wrote:

[snip]

A 1 mm csa' (cross sectional area) is enough for a 2 mtr length.

Would 1mm T+E be enough for several metres?


Taking 1mm csa' for low voltage is good for anything up to 10 mtrs really.
It's the low voltage part that makes the need for larger cross sectional
area on the cable a necessity.

John Weston wrote:
BigWallop, in article Uzmyd.5358$Ar5.1408
@text.news.blueyonder.co.uk, says...

Taking 1mm csa' for low voltage is good for anything up to 10 mtrs really.
It's the low voltage part that makes the need for larger cross sectional
area on the cable a necessity.



Actually, its the high current that "makes the need for
larger cross sectional area..." but I know what you mean
- low voltage devices require a correspondingly high
current to deliver the same wattage load so the amount of
copper in the cable has to be higher the lower the
voltage but the insulation can be thinner. (Follow
that??) :-)


According to http://tinyurl.com/67ex6, for 3 at 12v 50W
Halogens, you will need 2.5mm CSA twin to deliver the
150W at 12V over only 2m and will lose 0.5V along the
cable, meaning you only have 11.5v at the fitting. For
10m, you'd need 16mm cable(!) Don't forget that 150w
needs 12.5A at 12V , all assuming a resistive load.

IOW if the lights are very far apart you're better using more
lower-power transformers near the lights than one xfmr and long cable runs.

"John Weston" wrote in message
. ..
BigWallop, in article Uzmyd.5358$Ar5.1408
@text.news.blueyonder.co.uk, says...

Taking 1mm csa' for low voltage is good for anything up to 10 mtrs
really.
It's the low voltage part that makes the need for larger cross sectional
area on the cable a necessity.


Actually, its the high current that "makes the need for
larger cross sectional area..." but I know what you mean
- low voltage devices require a correspondingly high
current to deliver the same wattage load so the amount of
copper in the cable has to be higher the lower the
voltage but the insulation can be thinner. (Follow
that??) :-)


According to http://tinyurl.com/67ex6, for 3 at 12v 50W
Halogens, you will need 2.5mm CSA twin to deliver the
150W at 12V over only 2m and will lose 0.5V along the
cable, meaning you only have 11.5v at the fitting. For
10m, you'd need 16mm cable(!) Don't forget that 150w
needs 12.5A at 12V , all assuming a resistive load.

John


John, I must thank you for this. I meant to type 10 mm csa' for this
loading up to a length of 10 mtrs, and twice I have typed 1 mm csa'. I'm
slowly cracking up here. The little yellow van is waiting around the bend
for me. :-) Thanks again for updating and clarifying the details in my
replies.

On Thu, 23 Dec 2004 15:13:33 GMT, "BigWallop"
wrote:


"John Weston" wrote in message
...
BigWallop, in article Uzmyd.5358$Ar5.1408
@text.news.blueyonder.co.uk, says...

Taking 1mm csa' for low voltage is good for anything up to 10 mtrs
really.
It's the low voltage part that makes the need for larger cross sectional
area on the cable a necessity.


Actually, its the high current that "makes the need for
larger cross sectional area..." but I know what you mean
- low voltage devices require a correspondingly high
current to deliver the same wattage load so the amount of
copper in the cable has to be higher the lower the
voltage but the insulation can be thinner. (Follow
that??) :-)


According to http://tinyurl.com/67ex6, for 3 at 12v 50W
Halogens, you will need 2.5mm CSA twin to deliver the
150W at 12V over only 2m and will lose 0.5V along the
cable, meaning you only have 11.5v at the fitting. For
10m, you'd need 16mm cable(!) Don't forget that 150w
needs 12.5A at 12V , all assuming a resistive load.

John


John, I must thank you for this. I meant to type 10 mm csa' for this
loading up to a length of 10 mtrs, and twice I have typed 1 mm csa'. I'm
slowly cracking up here. The little yellow van is waiting around the bend
for me. :-) Thanks again for updating and clarifying the details in my
replies.

What, 10mm2 for a lighting circuit. Surely you are not serious.

Like the other poster said, more transformers is the way to go.

But that does beg the question of why to step down to 12V when there
are 240V halgen bulbs available.

Anyone know why?


Replace 'spam' with 'org' to reply

Roger wrote:

Hi
I am installing a set of 3 low voltage halogen lights in my kitchen ceiling,
however I find that the lead between light 1 and 2 is too short for my
purpose.

I have read that the wiring rating on this side of the transformer needs to
be substantial especially if its any length.

What gauge wire do I need to extend it to two metres?

I used normal ring mains T & E

Thanks
Roger

John Weston wrote:

BigWallop, in article Uzmyd.5358$Ar5.1408
@text.news.blueyonder.co.uk, says...

Taking 1mm csa' for low voltage is good for anything up to 10 mtrs really.
It's the low voltage part that makes the need for larger cross sectional
area on the cable a necessity.



Actually, its the high current that "makes the need for
larger cross sectional area..." but I know what you mean
- low voltage devices require a correspondingly high
current to deliver the same wattage load so the amount of
copper in the cable has to be higher the lower the
voltage but the insulation can be thinner. (Follow
that??) :-)


Actually its both. 1v loss on 250v is not as serious as 1v loss on 12v

and you get a lot more cable drop on a 5A LV 60W bulb than on a 0.25A
mains one.


According to http://tinyurl.com/67ex6, for 3 at 12v 50W
Halogens, you will need 2.5mm CSA twin to deliver the
150W at 12V over only 2m and will lose 0.5V along the
cable, meaning you only have 11.5v at the fitting. For
10m, you'd need 16mm cable(!) Don't forget that 150w
needs 12.5A at 12V , all assuming a resistive load.

Kalico wrote:


What, 10mm2 for a lighting circuit. Surely you are not serious.


Could be for big power.

Like the other poster said, more transformers is the way to go.

Depends. On thin celings with alnmostr no voids, cable in thnner than
trensformers...

But that does beg the question of why to step down to 12V when there
are 240V halgen bulbs available.

because they are 3 times as expensive and blow 10 times as quickly?


Anyone know why?


Replace 'spam' with 'org' to reply

Kalico wrote:

But that does beg the question of why to step down to 12V when there
are 240V halgen bulbs available.

Anyone know why?

I don't know the technical reasons, but from experience of having both
types of halogen lighting in our new kitchen, I'd say the 12v ones have
a much nicer quality of light.
12v ones produce a whiter, crisper light that creates those nice
twinkles on reflective objects. They create a more modern feel to the room.
The 240v ones give a more yellow light, similar to plain tungsten bulbs.
I'm not so keen and would change them for 12v ones if it wasn't so much
hassle.

On Fri, 24 Dec 2004 00:12:20 +0000, The Natural Philosopher
wrote:

Roger wrote:

Hi
I am installing a set of 3 low voltage halogen lights in my kitchen ceiling,
however I find that the lead between light 1 and 2 is too short for my
purpose.

I have read that the wiring rating on this side of the transformer needs to
be substantial especially if its any length.

What gauge wire do I need to extend it to two metres?

I used normal ring mains T & E

I like the idea of mains and low voltage wires being instantly
distinguishable. This must be safer than the other way round, but even
so...
--
On-line canal route planner: http://www.canalplan.org.uk

(Waterways World site of the month, April 2001)

"The Natural Philosopher" wrote in message
...
Kalico wrote:


What, 10mm2 for a lighting circuit. Surely you are not serious.


Could be for big power.

Like the other poster said, more transformers is the way to go.

Depends. On thin celings with alnmostr no voids, cable in thnner than
trensformers...

But that does beg the question of why to step down to 12V when there
are 240V halgen bulbs available.

because they are 3 times as expensive and blow 10 times as quickly?

If only it was just 10 times as quickly. Anybody want to buy some GU10
ceiling lights ?