Grounding

[vw55]

I have a switchboard currently installed at a building with a UFER grounding system. The landscape contractor for the project has an irrigation controller that he says requires a separate, three point grounding system consisting of three 8 foot ground rods triangulated and connected with #10 AWG conductor, then connected to the controller. I have yet to see the point of connection, whether it is the controller enclosure or a signal ground bus. The power for this controller comes from a panel served by the switchboard and connected to the building grounding electrode system via the neutral and equipment ground bussing. What concerns, if any, should I have regarding the controller ground system? Should I require this three point system to be bonded to the building grounding electrode system? If so, at what point in the system? Any and all comments would be appreciated.

 

[infinity]

Re: Grounding

If the irrigation system needs the three point grounding system as part of its listing than you must install it. This would be IMO a supplementary grounding system and would not be required to be connected all the way back to the service grounding system. The controller would still require a EGC sized according to 250.122. Supplementary grounding electrodes cannot be used for equipment grounding.