If the path being considered is neutral to ground, then the voltage you would get by touching the neutral when grounded, is the voltage drop that is present as a result of the current flowing on the neutral across the resistance of that neutral back to the point of bonding to ground. That wouldn't be zero when there is some current (and there will be if one phase of three is open and the others are conducting). But it wouldn't be that high unless there is something wrong with the neutral wiring (e.g. open or loose neutral). In adverse conditions, the neutral voltage relative to ground can be dangerous. In normal conditions it shouldn't be very much. How much voltage drop is considered acceptable on a 600/347 service?
