ripped camel

I've always used a product called "Dri" which is to be put on wires so they don't get water damage. My mom used to sell it for a chemical company, and for a demonstration they would plug something in spray the exposed wires, then put the exposed wires in a bucket of water while the thing had electric going to it! Needless to say if it can withstand that, I highly doubt water would damage my wires.

Steam cleaning is no different than just pressure washing with hot water.

Just use a degreaser, spray your wires with something that repells water, and blast away with a power washer. Do this at your own risk though. I'm not responsible if anyone screws this up because they did it wrong.