[Amps] what is a 4 wire 240VAC service?

[Ken Brown]

I first posted my comment inadvertantly to the Ten Tec list and got this 
response fro Jerry. He makes a good point, worth posting here. From Jerry:

The big hazard in the 3 wire situation with some load current in the
common ground/neutral conductor is that when the ground wire fails, 120
volts WILL be found on the case. I've know that to kill appliance users
on the spot. By running separate neutral and ground if the neutral opens
the user is still protected by the ground though the 120 volt
application fails to operate. If the ground fails the situation is safer
than in the 3 wire case, but its difficult to predict the possibility of
shock because it depends on the quality of the insulation of the appliance.

I've had to explain at least one such death in my working career, not
caused by me but as an expert witness hired by the attorney for the
widow and the estate.

73, Jerry, K0CQ

Pass my comments on to the other list if you will.

73, Jerry, K0CQ