Wire for 12v?

[Mr Sandman]

Is there a recommended wire/cable for 12v in domestic installations?

cheers

Steve

[ARWadworth]

It will very much depend upon the power you wish to use. Are we talking milliAmps or hundreds of amps?

Adam

[David Hansen]

On Tue, 5 Feb 2008 17:09:13 -0000 someone who may be "Mr Sandman" wrote this:-

What current will it be carrying, for what distance? What sort of heat, abrasion and so on will it be exposed to? Fixed or trailing?

[Archie]

12 V what? Type of cable depends on use. You wouldn't use bell wire to connect up 50 watt lights.

[Dave Plowman (News)]

Any cable will be fine for 12 volts. But if that 12 volts is at any sort of current the cable will need to be sized to suit.

[Bovvered?]

I'm assuming you're thinking about 12v halogen lighting? Just divide the total power by 12 to get the current and then take a look here:

[meow2222]

The numbers need to be run for each individual case. You need to consider ampacity and voltage drop primarily. What are you powering from what, at what current, over what distance? Is a regulated supply needed?

NT

[LiveCat]

I faced this problem a while ago. I think the main consideration is that the cable be appropriate for the current carried. I think it would also be good if the cable is visibly not a type used for mains wiring, to make the life of future electricians/surveyors/DIYers easier - what do others think about this?

[Roger Mills]

cable, that table assumes mains usage.

If using the cables for low voltage, the most important part of the table is the last two columns, showing voltage drop. Whereas dropping a few volts at

240v doesn't matter too much, dropping a few volts at 12v is very significant. This will result in the need for a much fatter cable for a given current than is suggested by the other columns in the table.

[meow2222]

ampacity is the same regardless of voltage. But as you say...

This is true for apps where V_drop is enough of an issue to require upsizing the cable, but for a lot of LV apps that isnt so. Thats why I asked about regulation.

NT

[Roger Mills]

I was actually replying to 'Bovvered' who quoted the table from the Electricians Guide - Fifth Edition.

I would suggest that one of the most frequent domestic LV apps is 12v halogen downlighters. If you're carrying 200 watts at 12v (4 x 50w lamps off a single transformer), that's more than 16A. Based purely on ampacity, you may be tempted to use 1.5mm^2 cable for this. But that would have a drop of

29mV/A/m - so you'll lose a volt for every couple of metres or so of cable - which would be significant for anything other than very short runs.

[Matty F]

When you've decided how many amps the wiring is going to supply, make sure that all switches can handle that current as well. Your usual 230 volt switches will probably NOT handle the current and will get very hot.

[Andy Burns]

If this is an LV halogen installation it should be the 230V transformer input at small amps being switched, not the 12V output at big amps.

[Matty F]

Sure but we haven't been told what it's for. I know a guy who put a 60 watt 12 volt light in his caravan, running off the car battery. He wondered why the battery kept going flat and the switch (designed for

1 amp AC) just about melted. He said "but I used a 100 watt 230v light with that switch"!

I do intend to run 12 volt wiring around my house for emergency lighting. I'll be using small LEDs for lighting.

[Mr Sandman]

Sorry for the delay, forgot i posted this! The cable will need to carry 1 amp 12volts.

Steve

[Adam Aglionby]

How far? voltage drop means you might get 10V dribbling out the end of a warm undersized conductor.

Adam

[Mr Sandman]

about 2 metres

Steve