Installation & Electrics — Power Cables

The important choice in cable is conductor cross-section, and it follows from how much current has to pass. Too thin means voltage drop over the length and a cable that warms up, exactly what you do not want in a room that is already warm and runs unattended for hours.

More copper is less heat

That is the whole reasoning behind the two sizes. More copper cross-section means less resistance, and less resistance means less heat at the same load. That counts at two moments: with equipment running at full power for hours at a stretch, and over length, because resistance climbs with every metre of cable. A short lead to a small fan asks something different from twenty metres to a full power strip.

1.5 or 2.5 mm2

White VMVL cable comes in 3 x 1.5 mm2 and 3 x 2.5 mm2, both by the running metre, so you buy exactly the length you need. Roughly: 1.5 mm2 is enough for a single lamp or fan, 2.5 mm2 is what you take for heavier loads or a long run. Add up your total wattage first, because a lamp plus the losses of its ballast plus a fan climbs faster than expected.

Ready-made or made up yourself

If you would rather not make cables up, the finished leads are here too: 2 and 4 metres with an earthed plug in 3 x 1.5 mm2, the C14 appliance leads with 2 or 4 metres of cable for the connection between ballast and reflector, and the right-angle IEC lead at 2 metres in 3 x 1.50 mm2, whose angled plug saves space behind equipment standing tight against a wall. There is also a lighter lead in 2 x 0.75 mm2; that is two-core, so without an earth, and belongs with equipment that does not call for one.

Frequently asked questions

How much cable do I need?
Measure the route rather than the straight-line distance: along the frame, round the corner, with a loop at the device so you can move it without pulling on the connection. Buying by the metre means measuring generously costs little.

Can I join cables together?
Every transition is another place where heat and resistance appear. One continuous length in the right cross-section beats two pieces with a coupler between them.

Where do I find the plugs for it?
Under Plugs: separate earthed plugs, couplers and IEC appliance connectors to fit yourself.