i think you are mising the point geraintthomas.
The curtesy light wire is a very light gauge wire if you connected it directly to the lights, it will not withstand the loade, and you will probebly blow the fuse.
relays are being use in many cases.
in our case we need to use it for the following:
"A relay is an electromechanical or electronic device through which a heavy load can be switched ON & OFF with a nominal input of current & voltage".
so in other words, we take the thin wire and use a relay, to power the lights with a thicker one. the lights calls for 25 amp fuse per side.
this is how it shhuld be connected:
(colors of wires are meeningless)
