On 07/10/2018 10:58, Harry Bloomfield wrote:
It happens that formulated :
4. Maybe a daft question but presumably any wire I use has to be able
to handle 15 amps (or if I go for the 360 watt one I might as well
ensure 20 amps)? Is the fact that it is 18v DC important when
selecting the cable? Eg is normal cable design for 20 amps at 240 v AC
correct?

20amps DC requires the same cable as 20amp AC. 240v cable will need to
be more robustly insulated than that for 18v.

I might suggest volt-drop becomes the overriding consideration.

Powering it from a power supply will possibly make it a bit unweildy to
use. A 240v version will probably be better.