Ground rod question on 600 amp service

[delfadelfa]

I have a job replacing three 4/0 SEU cables feeding 3 meter banks in the laundry room of one apartment building. The existing cables just follow each other up the outside of the building to the service drop. There are three existing 200 amp disconnects, one before each meter bank, that are in good condition and I plan on ending my new service cables in each disconnect.

There are no ground rods for the old service and I want to add them for the new service. Do I need one rod for each disconnect or do I add one rod and jump the disconnects?

 

[Dennis Alwon]

The most rods you ever need to comply with the NEC is 2 rods. If you get 25ohms with one rod then that would be sufficient however most people just drive two rods.

Normally I wire to the meter or somewhere ahead of the disconnect so only one wire is needed to the rod. You could just run 3 wires-- one from each disconnect to the rod/s.

 

[Cow]

I usually drive two rods, one at each end of the service. Then I'll horseshoe from one rod to the other right under the service disconnects. Then c-tap off that horseshoe into each disconnect.

 

[delfadelfa]

Thanks guys..