At what point in the system? Presuming this is a grounded system, the voltage will be zero at whatever location (often the service panel) that you make the N-G bond. At any other location, as Bob pointed out, there will be some voltage drop along the neutral wire, and there will not be a similar voltage drop in the ground wire, so there will be a difference in potential (however small) between neutral and ground.Is the neutral to ground voltage in 480Y/277V and 208Y/12OV systems supposed to be 0?
If there is any load on the system it will not be 0 due to voltage drop.
However is the difference starts exceeding say about 5 volts on a 120 circuit you may have other issues like open or unbonded neutrals.
If N-G voltage on 120V circuit is 11V (by metering), will this be a voltage drop issue?
Just curious as I dropped by .. isn't this situation called a ground loop ?