What wire type for 12v LED strips/tape?

[caravanboy]

Hi, I have a newly re-wired kitchen (by an electrician, all signed-off and properly certified) and they have left me a safely terminated 230v cable coming out of the wall that is ultimately connected to a wall switch so that I can add LED under & over cabinet lights once the new kitchen units were fitted...

Anyway, the units are here now and I am about to order the 12v LED driver (transformer) and white LED strips (60 x 5050 SMD LEDs per meter).

I'm very competent with 230v mains wiring but I've never really done any 12v stuff so this might sound a daft question...

I plan to have 3 indiviual 1m LED strips under the units and I've calculated that they will be draw power of 14.4 watts each which at 12 volts means a current of 1.2amps. Above the units I will have a single 3m strip which will draw 3.6 amps.

I plan to connect each of those in parallel to an LED driver with suitable capacity.

My question is... what sort of wire/cable should I used on the 12v side? I did have some of those RGB LED strips and the pre-installed wires from those seemed incredibly thin. Because of the higher current on the 12v side I presumed I needed decent thicker cable?

1mm T&E would be fine from a current point of view but given that I have to cut & solder the LED strips to exact length then I really need some sort of multi-stranded 2 core wire instead. I'm not sure of the proper name - is it "equipment wire"? Although elsewhere I saw someone (when talking about doorbells) say that solid cores were better for DC voltages.

I saw this 6amp two core mains cable at Maplin that would presumably also be fine, but I wanted something more discrete without the external sheath since it is only 12v:

http://www.maplin.co.uk/2-core-6a-mains-cable-3182y-83

Anyway, can anyone recommend a suiatble type of wire for the 12v side, or am I worrying about nothing? The cables will be about 1 to 2m long from the driver to the start of the LED strip/tape.

Thanks!

 

[Jackrae]

multi-stranded bell wire.

 

[Monkeh]

The size of the wire depends on the length you need to run, but I'd suggest 20AWG or better.

From that horrible Maplin place you should not shop at: http://www.maplin.co.uk/twin-power-cable-20666

The '6A' (stupid, ignorant naming scheme) will be fine for a run of about two metres.

Bell wire is not suitable, and whoever told you DC is better with solid conductors is to be ignored.

 

[caravanboy]

From that horrible Maplin place you should not shop at: http://www.maplin.co.uk/twin-power-cable-20666

The '6A' (stupid, ignorant naming scheme) will be fine for a run of about two metres.

Brilliant thanks, that Maplin XS70M 6 amp stuff looks like just the sort of stuff I imagined. I could only think of speaker cable and bell wire but they aren't usually rated for current. The Maplin one has a sensible "Twin Power Cable" name

Re. your comments on Bell Wire, I guess it would be suitable providing it can handle the current - unless there's another reason? I see that the 6A Maplin one you recommend has a CSA of 0.57mm2 and after the first reply I did actually lookup this multi-stranded bellwire on the B&Q site that claimed to be "1.5mm", which I assumed meant CSA, although the actual description contradicts the title and says 4.5mm:

Tower Bellwire Twin Strand 437888 White 1.5mm x 10m

Anyway, I'll be getting something similar to the Maplin one now I know what the proper name is...

Many thanks!

 

[Monkeh]

There's absolutely no useful information on the B&Q site. It could be anything. Bell wire is typically quite small.

 

[EFLImpudence]

Automotive wire is sold with current rating.

It carries DC is stranded for some reason.

May be a bit long

 

[Monkeh]

Automotive wire is sold with current rating.

Which is stupid and totally irrelevant as voltage drop still has to be accounted for.

It carries DC is stranded for some reason.

Hmm, might be because solid cable is a cheap hack for situations not exposed to movement or vibration?

 

[EFLImpudence]

Which is stupid and totally irrelevant as voltage drop still has to be accounted for.

Yes, I know but OP only wants a meter or so.

Hmm, might be because solid cable is a cheap hack for situations not exposed to movement or vibration?

It was sarcasm - agreeing with you.

 

[Monkeh]

Which is stupid and totally irrelevant as voltage drop still has to be accounted for.

Yes, I know but OP only wants a meter or so.

The ratings are, shall we say, ambitious. 5.75A from that 0.65mm2? Only for a meter and a half, two at the outside.

Hence Maplin. If you need less than 10m you may as well use the likes of them. At least if there's one close, I won't pay them to deliver things.

 

[EFLImpudence]

The ratings are, shall we say, ambitious. 5.75A from that 0.65mm2?

Is that from personal experience?

Or does it show how conservative the IET ratings for domestic cables are?

I can't imagine Mr.Ford or Mr.Honda wanting to spend a penny more on cables larger than necessary nor wanting their cars to catch fire.

 

[Monkeh]

The ratings are, shall we say, ambitious. 5.75A from that 0.65mm2?

Is that from personal experience?

Or does it show how conservative the IET ratings for domestic cables are?

I can't imagine Mr.Ford or Mr.Honda wanting to spend a penny more on cables larger than necessary nor wanting their cars to catch fire.

5.75A across 2m of 0.65mm2 yields 627mV drop. At 12V, that's over 5% and that's all I'm willing to lose. Even at 13.8V, that's 4.5%.

Temperature is not the issue here.

 

[caravanboy]

5.75A across 2m of 0.65mm2 yields 627mV drop. At 12V, that's over 5% and that's all I'm willing to lose. Even at 13.8V, that's 4.5%.
Temperature is not the issue here.

Monkeh, so should I be looking at a fatter cable? I actually did a bit more research on these LED strips and also came across people saying that the higher power ones didn't seem to draw as much current as they were rated for. There were then all sorts of theories about voltage drops across the length of the strip itself (with them commonly being used in 5m lengths) and discussions about the copper in the strips being much less than the CSA of the cables being proposed.

I will probably just go with the Maplin cable (or similar) that was proposed earlier. If ever I have a problem that the LEDs have been damaged (by the voltage drop) then the strips and cable are so cheap anyway that I can always replace them all. If they last 2 years I'm sure the technologies will have moved on even more by then anyway.

Thanks to everyone for your help and suggestions.

 

[Monkeh]

5.75A across 2m of 0.65mm2 yields 627mV drop. At 12V, that's over 5% and that's all I'm willing to lose. Even at 13.8V, that's 4.5%.
Temperature is not the issue here.

Monkeh, so should I be looking at a fatter cable?

No, the stuff I suggested before is fine.

I actually did a bit more research on these LED strips and also came across people saying that the higher power ones didn't seem to draw as much current as they were rated for. There were then all sorts of theories about voltage drops across the length of the strip itself (with them commonly being used in 5m lengths) and discussions about the copper in the strips being much less than the CSA of the cables being proposed.

I'd be happy to look at a strip and prove or disprove these theories. Otherwise, they're just random thoughts on the internet, which are usually wildly off the mark.

If ever I have a problem that the LEDs have been damaged (by the voltage drop

Volt drop will not damage an LED. In fact, they will exhibit longer life at the lower currents. They just won't be as bright.

 

[caravanboy]

I'd be happy to look at a strip and prove or disprove these theories. Otherwise, they're just random thoughts on the internet, which are usually wildly off the mark.

Volt drop will not damage an LED. In fact, they will exhibit longer life at the lower currents. They just won't be as bright.

Ok. I guess there would be a voltage at which they would fail to work but that would probably need quite a significant drop and not one that I'll encounter.

If you're interested, this was the main thread I read about it, although mine are white only, not RGB. It sounded like they knew what they were doing (as do a lot of things found online of course) although their explanations seemed reasonable to me.

http://electronics.stackexchange.co...5050-led-strip-draw-as-much-power-as-i-expect