Grounding for a 800 Amp Utility Service Panel and Disconnect Switch

[Samardas]

I have a service disconnect panel with a utility meter for an 800A, 480V, 3 Phase service. This is an old warehouse where this new service panel will be installed at a location much further from the existing service which will be removed. I am looking at the NEC 250 section, but not sure what type grounding I should recommend. For example, can I show a new ground rod/or pipe and connect it to the ground bus of the panel? Also, can I show the neutral and ground bus to be bonded and the panel to be grounded to the ground bus? Do I also need another ground (say, UFER) or cold water pipe ground to be connected to the ground bus? Customer is in a rush and I need help as soon as possible. How can you please help? I am attaching a partial single line for your reference. Thanks a LOT.

 

[augie47]

All of your grounding electrode conductors should connect to a point from the load send of your service lateral up to your grounded buss {250.24(A)(1)}
You should have main bonding jumper to connect the service disconnect enclosure and the grounding buss to the grounded conductor.
Any and all grounding electrodes available on the premises should be a part of your grounding electrode system.{250.50}

 

[Samardas]

Grounding for a 800 Amp Utility Service Panel and Disconnect Switch

Thanks a lot. Did you look at the partial single line I attached with my post? Please advice what (and how) should be added to the grounding I have already shown on the diagram.

 

[augie47]

I did and noted your had the UFER connected to the grounding buss, thus my comment .

 

[Samardas]

Grounding for a 800 Amp Utility Service Panel and Disconnect Switch

Hello augie47, Thanks for your reply again. My next question is do I still need the UFER or it is not necessary. Can one ground Rod be sufficient for the grounding system? I am a little bit confused with the explanation in NEC.

 

[augie47]

As noted in 250.50, you must incorporate all the electrodes available.
IF a UFER is available then you must connect to it (if the building has a concrete encase electrode but it was not made accesible at the time of construction you haver a situation where you need to consult your AHJ as that sitaution is addressed differently by local enforcement). The same is true for all the electrodes listed in 250.52(A)(1) the (7).. if available, you must connect to them.
If none are present then you must provide one. If a rod is the only electrode available the it may need to be supplemented.
All this is covered by Art 250 Part III.