Grounding Multiple Services In A Single Structure

[rjken1969]

Greetings,

I'm a new member to the forum. I usually can find someone else that has asked asimilar question, so I refer to previous posts. This one I can't find:

I have a new multi building residential complex that sits on a common garage.Each building has a separate utility service switch and transformer. I'mlooking for information on grounding the services. The buildings all sit on acommon steel garage structure. Currently the plans call for the standard groundingas outlined in 250.52.

My questions is this, can all the services be tied to a common structure (thegarage)?

 

[Gregg Harris]

Greetings,

I'm a new member to the forum. I usually can find someone else that has asked asimilar question, so I refer to previous posts. This one I can't find:

I have a new multi building residential complex that sits on a common garage.Each building has a separate utility service switch and transformer. I'mlooking for information on grounding the services. The buildings all sit on acommon steel garage structure. Currently the plans call for the standard groundingas outlined in 250.52.

My questions is this, can all the services be tied to a common structure (thegarage)?

See if this helps
250.30 Grounding Separately Derived Alternating-Current Systems. In addition to complying with 250.30(A) for grounded systems, or as provided in 250.30(B) for ungrounded systems, separately derived systems shall comply with 250.20, 250.21, 250.22, and 250.26.

(6) Grounding Electrode Conductor, Multiple Separately Derived Systems. A common grounding electrode conductor for multiple separately derived systems shall be permitted. If installed, the common grounding electrode conductor shall be used to connect the grounded conductor of the separately derived systems to the grounding electrode as specified in 250.30(A)(4). A grounding electrode conductor tap shall then be installed from each separately derived system to the common grounding electrode conductor. Each tap conductor shall connect the grounded conductor of the separately derived system to the common grounding electrode conductor. This connection shall be made at the same point on the separately derived system where the system bonding jumper is connected.

 

[augie47]

With no disrespect toward Gregg, but IF I understand your situation you have multiple services and not a SDS 250.30 situation.
If the garage is common to all the buildings, IMHO, you need to assure a common electrode system per 250.58.

 

[rjken1969]

Correct, there are multiple services.

My thought is each service will have a grounding electrodes in accordance with 250.52. And the common electrode between buildings required by 250.58 will be the garage steel. I just need to ensure the steel is continuous between each building, if not I will provide a GEC.

Hopefully I am on the right track.

 

[jaggedben]

I just need to ensure the steel is continuous between each building, if not I will provide a GEC.

Hopefully I am on the right track.

Technically (if the steel is not continuous) you need bonding jumper(s) to connect it all together. See 250.53(B). Each service will have it's own GEC.

But yes, you are on the right track.

 

[Gregg Harris]

With no disrespect toward Gregg, but IF I understand your situation you have multiple services and not a SDS 250.30 situation.
If the garage is common to all the buildings, IMHO, you need to assure a common electrode system per 250.58.

Good catch Augie47 I miss- read and picked up on separate switches and transformers leading to SDS