Hi Martin,
I don't think you'll find any simple "conversion" courses as such. Although the electrons follow the same laws of physics everywhere, American practice has much which is different from the way things are done in the U.K. For example:
* Different cable sizes, derating factors, and so on.
* Different standard circuit arrangements and diversity rules.
* A multitude of supply systems for different purposes: 120/240V 3-wire, 120/208 wye, 277/480 wye, 240 delta, plus a few other "oddball" systems, all in contrast to the U.K. where it's pretty much either 240V single-phase or 240/415V 3-phase.
* Very different grounding (earthing) arrangements in some circumstances, even though the basic service generally resembles our PME/TN-C-S to some extent.
That's just a few things to start thinking about. As I'm sure everyone else will also tell you, the rules for licensing also vary considerably from one state to another.
