Great responses, guys!
The millivolt drop test is a no-brainer that I should have tried...oh well, next time it will come to me easier.
It seems obvious that I'll have to find a shut-down opportunity..or some way to parallel the breaker during trip unit replacement??? just to be sure there is no interruption in service. Don't know if there is a way to clamp on to the load side wiring of the breaker with the wires from a parallel arrangement. Never seen it done, and it scares me to think of accidentally crossing my phases...one of those "I know this is hooked up right, but do I really trust my life on what I think I know" kind of situations.
Ah, its not worth the gamble. There has to be a way to shut the computer center down sometime.
