Logn run of 12v signal for RGB changing LED strip

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I've got some quite high current requirements for a cable run - what would be the suggested type of cable. Has to be 4-core to support 10A at 12v.
 
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Use the same calculations of voltage drop as for mains cables It doesn't matter if the voltage is 230 or 12 the voltage drop is set by current and resistance of the conductor.

If the voltage drop is too high for the LEDs then use a LED driver with remote voltage sensing, The driver will increase its output voltage higher so the the voltage at the LEDs as measured via the sense wires is the correct voltage for the LEDs The wires for the sensing are not carrying current so can be small, telephone cable has been used for this function.
 
Yes - the high-brightness RGB type can consume 14.4W/m
I have a skylight of 6.75 x 1m and am running a strip all the way around the inside. So that's 15m = 216W (I have to run that off 2 drivers, each 108W).
Another strip is 9m, so that's about 130W.

To be honest, I'm going to start off with the non-high-brightness tapes (which are half of the above rating) but I want to run cables capable of taking the brighter type should I decide that I need to upgrade later.
 
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OK.

As per above, voltage drop is voltage drop is voltage drop - the calculations are the same at 12V as 230V.

I assume you can't put the drivers local to the lights?
 
Well, I was originally proposing to do that, but the electrician suggested that might make it harder for maintenance.
He's thinking of running 1.5mm cable - which I understand from a quick Google has a resistance of about 0.25ohms over 10m. This would equate to a voltage drop of 2.5v - which is not insignificant.
 
Well, I was originally proposing to do that, but the electrician suggested that might make it harder for maintenance.
He's thinking of running 1.5mm cable - which I understand from a quick Google has a resistance of about 0.25ohms over 10m. This would equate to a voltage drop of 2.5v - which is not insignificant.


A voltage drop of 2.5v on a 12v circuit is 20%, lighting circuits should not exceed a 3% VD.
 
When you say "should" - is that a building regs thing, or sensible advice?

I've deliberately gone for a worst-case with my 2.5v, but even so, I'm beginning to think that I may have to find another location for my DMX controllers & PSUs.
 
Use the same calculations of voltage drop as for mains cables It doesn't matter if the voltage is 230 or 12 the voltage drop is set by current and resistance of the conductor.
The calculations may be the same but unlike with mains where you can work on standard assumptions in an ELV DC system you really need to find out how much volt drop is acceptable before you start.

I would really try and get the drivers as close as possible to the load. Keeping volt drop sane on a 12V system starts to require stupidly big cables once you go beyond a few meters.
 
Yes, I think it should be possible.
The actual figures are likely to be not that bad.
- I'm probably going to make do with 7.7W/m strips
- We can probably keep the cable run to 7m
- Use 2.5mm core cable.
So I think with all that figured in, it would be close to 5% VD.

However, if I can exploit some void space with a silicone-sealed access hatch, then it would save space elsewhere.
 
You'll probably also find that the drivers are constant current drivers, so the normal voltage drop calculations become less relevant other than just as a guide.
 
When you say "should" - is that a building regs thing, or sensible advice?

I've deliberately gone for a worst-case with my 2.5v, but even so, I'm beginning to think that I may have to find another location for my DMX controllers & PSUs.

The 3% figure I quoted is the one from the IEE regs for use in lighting circuits.
Are these the type that use a varying current/voltage to control colours?
 
Yes, I presume that's how it works, but each colour has it's own supply - which makes me realise that there are 4 cores to consider here - so if I go for 2.5mm x 4, there would be only about 1.5% VD. Doh!
 
You'll probably also find that the drivers are constant current drivers, so the normal voltage drop calculations become less relevant other than just as a guide.

That is a possibilty in which case the drivers will compensate for the voltage drop but you will need to check with the manufactures what the maximum drop that the driver can compensate for.
 

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