I have a question for the electrical gurus out there! We are nearing the completion of our pool build and have selected the pool lights. We will be using 3 no. 35w/12 volt led fittings. We have an approximate 25m run from the power supply in the pool equipment room to the farthest light. My questions:-

1. Type of cable to be used? Cable will be run in conduit below ground.

2. Size of cable given the distance to the lights.

Assuming these LED's use a proper driver circuit and not just a resistor, they should be able to cope with some voltage drop, so 1.5mm2 (16awg) multi-strand speaker wire should do the job.

If the LED's use only resistors for current limiting, they will be much more sensitive to voltage drop, so you might want to go as high as 2.5mm2 (14awg) or 4mm2 (12awg).

Either way, get yourself the silver plated wire so it doesn't corrode though - normal OFC copper will turn black in no time, silver won't.

Whatever you do, don't buy it at a hi-fi shop - find a PA systems shop for decent wire at a reasonable price.

You'd also probably want a DC power supply rated at at least 12 Amps, so it's not running at 100% duty cycle, and because many of the Chinese ones never actually make their rated output