Glad you found us, Rosko, welcome to the board. It is always nice to have a new builder getting interested in creating his own little trailer. If you can build a trailer, you should have no trouble with the wiring, it's just a bunch of wire and routing it to the correct locations.......... :-) Think of it as water pipes, one wire supplying water and the other sending it back. Running the 12 volt is probably the easiest but the 110 volt is similar except the voltage is about 9 times stronger!
Read the info found in the links above and ask any questions you feel you need answers to. Good luck on your build. Take pics, post em, visit other TD builders, check out a local TD gathering and by all means, enjoy the project which you will probably be using for some time.
Roly
