I'm trying to wire in a fuse box, most of the wiring is done and ready for connecting. The only thing I'm not to sure about it where to get my live feed to the relay so that the power is controlled by the ignition. I have found the tail light (number plate light) cable and was thinking of taking the feed from that, by cutting in and the soldering on to it.

Now the dumb question! - am I right in thinking that I need to tap into the brown/blue cable as that's the live and the blacks the earth??

As you can tell I'm not that good on the old electrics, all help will be well appreciated!!