Secondary grounding of industrial equipment

[102 Inspector]

Because of my limited knowledge of this issue, I am asking the professionals. In an industrial building, the 3 phase equipment is being fed via a ground buss and then a secondary ground rod is drilled through the fllor and connected to the equipment by a #10 conductor. The equipment is from China / Japan and I have not looked at any installation instruction yet. Is it common practice to drive additional grounding rods at equipment locations and does this violate any grounding issues due to multiple points of grounding being provided? The maintenance man says this is how we do it, and I am thinking this just does not seem correct to establish multiple grounding points without having them all bonded together. Any assistance will be greatly appreciated.

 

[jumper]

As long as the equipment is bonded by an EGC, you can add an additional rod/electrode.

 

[petersonra]

Because of my limited knowledge of this issue, I am asking the professionals. In an industrial building, the 3 phase equipment is being fed via a ground buss and then a secondary ground rod is drilled through the fllor and connected to the equipment by a #10 conductor. The equipment is from China / Japan and I have not looked at any installation instruction yet. Is it common practice to drive additional grounding rods at equipment locations and does this violate any grounding issues due to multiple points of grounding being provided? The maintenance man says this is how we do it, and I am thinking this just does not seem correct to establish multiple grounding points without having them all bonded together. Any assistance will be greatly appreciated.

This is indeed a common practice. Whether it serves any useful purpose is debatable.

As a practical matter, the local ground bar is bonded to the GES through the EGC, if that matters any.

 

[102 Inspector]

I knew I would get the proper guidance from this group. Thanks for the clarification and graphics with the applicable code section.

 

[infinity]

As long as it has an EGC then it won't end up like this very dangerous installation: