Separate Structure?

[xguard]

I'm replacing an ancient outdoor switchboard at one of our buildings. The existing one is mounted on an exterior wall of the building. In an effort to reduce down time we're building a separate structure to house the service equipment about twenty feet away from the existing switchboard. I'm planning to have a ground rod at the new service disconnect. I'm wondering though about tying into the existing system. The new service rack will also have a 1200 amp panel that will feed three panels inside the building, the three panels are located well into the building.

Do I need to run a bonding conductor from the outdoor grounding electrodes indoors to each panel? Or is the connection at the service adequate? I didn't know if having the service and panel a short distance away from the building would cause this to fall under the 250.32.

This is a building on a large property under single management if that's relevant.

 

[Dennis Alwon]

It appears you can take advantage of the exception if you fall under these demands

225.31(B) Location.

The disconnecting means shall be installed either inside or outside of the building or structure served or where the conductors pass through the building or structure. The disconnecting means shall be at a readily accessible location nearest the point of entrance of the conductors. For the purposes of this section, the requirements in 230.6 shall apply.
Exception No. 1:
For installations under single management, where documented safe switching procedures are established and maintained, and where the installation is monitored by qualified individuals, the disconnecting means shall be permitted to be located elsewhere on the premises.

 

[jaggedben]

...

Do I need to run a bonding conductor from the outdoor grounding electrodes indoors to each panel? Or is the connection at the service adequate? I didn't know if having the service and panel a short distance away from the building would cause this to fall under the 250.32.
...

It would appear to fall under 250.32. You only need to run EGCs between the two structures. However your equipment in the existing building needs to be connected to the (presumably) existing grounding electrode system at the building. Do you have junction boxes taking the place of the old switch gear, for splicing the existing feeders to the three panels? Can you run grounding electrode conductors from those junction boxes to new or existing grounding electrodes at the building? I believe that would satisfy 250.32.

Your description raises some other questions as Dennis alludes to. But with three feeders you may be okay. See 225.30(B) as well as the exception Dennis mentioned.

 

[xguard]

It would appear to fall under 250.32. You only need to run EGCs between the two structures. However your equipment in the existing building needs to be connected to the (presumably) existing grounding electrode system at the building. Do you have junction boxes taking the place of the old switch gear, for splicing the existing feeders to the three panels? Can you run grounding electrode conductors from those junction boxes to new or existing grounding electrodes at the building? I believe that would satisfy 250.32.

Your description raises some other questions as Dennis alludes to. But with three feeders you may be okay. See 225.30(B) as well as the exception Dennis mentioned.

We're running new feeders from the outdoor panel to the inside panels. The existing feeders are over fifty years old in really bad shape, especially the outdoor portions. We can run a new conductor from the service rack grounding electrodes to the building's existing system (hopefully existing).

We look to be okay with 250.32(B), as each feeder originates in the outdoor panel and each will terminate in a disconnect or mcb in a panel inside the building. I don't think 225.31 is an issue as the service disconnect will be adjacent to the new outdoor panel and disconnect all the power going into the building. That's how it looks to me anyway, I've been wrong before.

Everything will be labeled and we can write up a procedure for disconnecting power to the building. We have electricians full time that are assigned to the complex.