In our marshaling rack while checking the Grounding system we find out that system earth and panel earth are having the voltage different of 0.678 mV. that is both are shorting circuiting. Let me know that, is it ok? becoz what i understand that both should not be in short circuit condition.

 

All the various earths are conencted together at some point in your plant somewhere. So there should not be a whole lot of voltage difference and you should see continuity between them.

--
Bob

 

Are you saying 687mV or 687uV? If microvolts, what are you using to measure it?

 

Usually there are two different ground bars in an installation. The safety ground and the instrument ground. Most of the time they are isolated in order to avoid ground loops. Nevertheless they both come together at the site grounding system grid. Where is this voltage being measured (e.g. between the power supply 24+ and the ground, between the marshalling 24+ and ground)?