I believe what I'm looking at is a 3ph 480v Delta ungrounded service. The reason I question it is because I'm not familiar with the voltages I'm getting.
A-B 480v
B-C 480v
C-A 480v
to ground
A-G 480v
B-G 480v
C-G 6v
This is in the factory I just started working for, but hese voltages don't seem right.
I believe the C phase is shorted to ground. If so, is it possible for this to cause stray voltage onto the ground of another service in thie same facility. Are there any suggestions on how to isolate the ground-fault.
You may have a corner grounded delta and if so this is how I look at it:
It is not "shorted to ground." The "C" phase been chosen to be grounded in your case where a grounded "B" phase is more common is a corner grounded delta.
Remember that a connection that is unintended can be considered to be a short circuit. What you have described is intended and not considered to be a short to ground.
Please understand that what I'm about to describe is only being used to illustrate what a "grounded conductor" is. Using 120/240v 1ph3w or a 208y/120 and a 480y/277 3ph4w as an example the neutral in each of these is commonly grounded. The neutrals, which are now grounded conductor, after it leaves the service entrance are to be kept insulated and isolated from the equipment grounding conductor(EGC). The neutral (N) is the grounded conductor and is one of the current carrying conductors.
The EGC provides a path back to the source should the be as line or phase to ground fault. The EGC provided a path back to the source such thar the over current protective device is able the clear the fault
In you case the "C" has been grounded and what you now should have is a both an "C" phase conductor that is "grounded" and a separate EGC. The "C" phase after it leaves the point where it is grounded should be insulated and isolated from the EGC just as the neutral would be. The EGC in a corner grounded delta provided a path for the fault current to flow back to the source such that an overcurrect protective device wuold be allowed to clear the fault.