Adding ground to 3 phase 3 wire?

[circlet]

Well grounding is for safety, right? I have a few machines running reliably on 3 phase 3 wire 200V which is what is provided by the power company. Nothing has ever been grounded and electricians here seem to think that is just ok, though I do not agree. However, I got a machine recently that is giving a very light and constant shock if touched. I am guessing there is something slightly out of balance as well I should take the machine apart and see if there is a physical problem. I am assuming adding a ground from the machine frame to the earth will be a good idea anyway. The steel frame of the building is buried in the earth and a number of things running on the seperate single phase service are grounded to the building frame.

What is the best solution for grounding my 3 phase service, building frame or through a dedicated grounding rod in the earth? Why can they not just have more than three wires in the service??

Thank you.

 

[George Stolz]

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