I live to serve ... would you like fries with that?
Pretty straight forward hookup, especially with a simple transformer with one primary and one secondary winding. Mine is 120v in by 6.3v out. The breaker and switch wiring didn't change on mine - that's all on the hot side of the AC connection to the wall. As you can see, I just cut out a couple sockets on the power strip to mount the transformer.
- Neutral side of the AC wall feed goes straight through to the socket.
- Hook the neutral side of the transformer's 120v winding to that straight through feed.
- Hook the other side of the transformer's 120v winding to the hot leg of the AC wall feed.
- Hook one leg of the secondary winding to the hot leg of the AC wall feed also.
- Hook the other leg of the secondary winding to the socket.
Just tack the secondary winding wires in place temporarily until you verify that you've got those right with a VOM in the socket. If you've got it right, you should see the voltage drop. If the voltage goes UP, reverse those two wires and check again.
Gets more complicated with more windings as you have to figure out which leads are which. I've seen a few examples where folk have both 6v and 12v taps, and have wired those up to provide different output voltages to multiple sockets. Gives them some flexibility, but I'm happy with what I got, mostly because it's doing the job, but also because it doesn't take up much space in the rack.