Electrical – What causes power to enter ground

In trouble shooting this we found that an outside outlet had 70 volts coming through its ground. We went inside and disconnected everything but what is shown. The white is to the common, the red and black go through each side of the 2 pole 60 amp breaker. Testing from the common to ground shows that this voltage still exist. In testing continuity between black and white, we found that it tested positive. We went as far as to see that an outside halogen light was the reason for this continuity showing a solid connection.

With all power connected, everything works, I just show this voltage passing between ground. Is this a common occurrence where some voltage will pass between power and ground? My gut says no, but then I am a pseudo electrician. We have one coming, but would like to be able to tell him just about where the issue is.