Class 320 Service With Two Separate 200 A Disconnects - Grounding

[ARK1985]

I'm looking for some guidance on a class 320 service installation that I am going to be doing at my personal (soon to be built) residence. For reference, I am a licensed master electrician in my home state, but I am not a contractor so I don't regularly do residential installations. Hopefully this question doesn't violate the forum rules, but if it does feel free to close it.

For the new residence that we're building this year, I'm looking at installing a 320 amp service that will serve two 200A load centers in the house. I've done an installation like this with a 320A Meter/Main combination unit on another residence previously, but am struggling to get metering equipment with the current supply chain issues that we're dealing with. I did manage to get a 320 A meter and separate 200A single breaker outdoor disconnects, and would like to mount them all together outside of the house.

My question comes down to proper grounding/bonding for this arrangement. With the Meter/Main combination unit, a single set of grounding electrodes were bonded to the neutral bus and enclosure. In this case, should I have a separate set of grounding electrodes for each of the disconnects (see Image 1 - attached)? Would one set of grounding electrodes suffice, and if so, do I bond the ground terminals between all three enclosures (see Image 2 - attached)?

 

[augie47]

Unless your POCO prevents it, likely the simplest is to connect your GE conductor(s) to the meter enclosure.
(Your "single ground diagram".. but your don't need to extend GEC into the breakers..the neutral will suffice)
As an alternate you can have GECs from each disconnect or a common GEC with taps to each disconnect
(your diagram "Multiple" but each GEC can run to the one set of ground rods)

 

[ARK1985]

Unless your POCO prevents it, likely the simplest is to connect your GE conductor(s) to the meter enclosure.
(Your "single ground diagram".. but your don't need to extend GEC into the breakers..the neutral will suffice)
As an alternate you can have GECs from each disconnect or a common GEC with taps to each disconnect.

Thanks for the quick reply. If I'm reading this correctly, I think you are referring to the second image that I have posted above, where the GEC is connected to the bus in the meter enclosure, and taps are run to the two service disconnects.

This would be the easiest implementation, though I was wondering if I should be concerned with the GEC running into the meter enclosure considering that the PoCo will be locking it once energized (thus limiting my future access to it). Maybe that's not something I really need to be concerned with though...

 

[augie47]

Some POCOs will not allow the connection in the meter for that and other reasons.
Either of your diagrams is acceptable (only 1 set of ground rods is needed)