You will probabally need an adaptor (buy from any accessory supplier or on line from Towsure) To test for reverse polarity you will also need a tester which simply plugs into any caravan mains socket. Should this prove that you have reverse polarity (poss to neg and neg to poss)you will need to rewire your adaptor or take two adaptors, one of which has been previously rewired. These MUST be clearly identified, I have wound RED tape around the correctly wired adaptor and BLACK tape around the "modified" one.