On Sat, 4 Jul 2009 23:40:18 -0700, John E.
wrote:

I have been asked to offer an opinion in a sensitive situation.

A machinist moved his shop across town and required some rewiring (3-phase
outlets, conduit, etc.) in order to locate some machines where he wanted
them.

He hires a guy who's not a pro (and later discovers is not insured) but has
done shop wiring before and had a good attitude and track record. The guy
does good work. No complaints about the quality of his work.

Owner throws the switch, all works fine.

The story continues 4 weeks later when the very expensive CNC fries its
controller PCB to the tune of $4000.

Turns out the voltage in the shop was upward of 245 and the taps in the CNC's
power supply were set for 220.

What is the legal and moral responsibility of each party?

What will not be helpful are replies about the character or intelligence of
either of the players or their actions.

Thanks.

Since i am not sure where you are at, and you did not mention. In the
US if the shop owner knowingly hired an non-licensed electrician to do
the install, 'e would have to eat the loss. Similar in UK and much of
Europe. The selected tap voltages and delivered line should have been
within normal acceptance range for the controller power supply. As
for why the controller fried that is unclear at this time; causation
from the mains connections has yet to be discussed adequately.