Grounding Multiple Services on same building

[Canton]

Hello all,

I have a unique situation, I have 3 service laterals, 3 meters and im putting in 3 service disconnects. All are going on the same building that has been divided into 3 tenet build-out offices with fire rated walls. All service laterals are from the same poll transformer. I have a cold water that should qualify as a grounding electrode that comes from another adjacent building owned by the same landlord.

How should all these services be grounded? I'm driving a ground rod with a #6 for each service but do I have to bond all 3 electrods together because they are on the same building?

How about the one cold water ground for all 3 service

Thanks

 

[kwired]

Hello all,

I have a unique situation, I have 3 service laterals, 3 meters and im putting in 3 service disconnects. All are going on the same building that has been divided into 3 tenet build-out offices with fire rated walls. All service laterals are from the same poll transformer. I have a cold water that should qualify as a grounding electrode that comes from another adjacent building owned by the same landlord.

How should all these services be grounded? I'm driving a ground rod with a #6 for each service but do I have to bond all 3 electrods together because they are on the same building?

How about the one cold water ground for all 3 service

Thanks

How is the water distributed to each tenant section of the building?

 

[Canton]

One water main into the building from the adjacent building. The water is not divided, cold water branches off and feeds each of the 3 tenants (no metering or billing individually), same with the hot water. There is only one hot water heater for all three. Metallic piping through-out for all three, no isolation.

 

[kwired]

One water main into the building from the adjacent building. The water is not divided, cold water branches off and feeds each of the 3 tenants (no metering or billing individually), same with the hot water. There is only one hot water heater for all three. Metallic piping through-out for all three, no isolation.

Then each service needs A GEC run back to within 5 feet of main water entrance. Or you can run a single GEC and make taps to each service, but they would need to be irreversible splicing methods.

250.24 Grounding Service-Supplied Alternating-Current Systems.
(A) System Grounding Connections. A premises wiring system supplied by a grounded ac service shall have a grounding electrode conductor connected to the grounded service conductor, at each service, in accordance with 250.24(A)(1) through (A)(5).

From 250.24 it says each service must connect to the grounding electrode system.

The underground metal water piping is part of the grounding electrode system, (250.50 + 250.52)but attachment of the GEC must be within 5 feet of entry(250.68(C)(1).

 

[augie47]

A couple of questions which might add possibilities:
What rating of fire wall is separating the occupancies ?
Is there any non-metallic piping involved
Is there structural steel ? If so is it common to all occupancies ?

 

[Volta]

Then each service needs A GEC run back to within 5 feet of main water entrance. Or you can run a single GEC and make taps to each service, but they would need to be irreversible splicing methods.
....

I don't think the connections from the GEC taps to the GEC have to be irreversible. I think most split bolts would suffice.

Service with Multiple Disconnecting Means Enclosures.
If a service consists of more than a single enclosure as permitted in 230.71(A), grounding electrode connections shall be made in accordance with 250.64(D)(1), (D)(2), or (D)(3).
(1) Common Grounding Electrode Conductor and Taps. A common grounding electrode conductor and grounding electrode conductor taps shall be installed. The common grounding electrode conductor shall be sized in accordance with 250.66, based on the sum of the circular mil area of the largest ungrounded service-entrance conductor(s). If the service-entrance conductors connect directly to a service drop or service lateral, the common grounding electrode conductor shall be sized in accordance with Table 250.66, Note 1.

A grounding electrode conductor tap shall extend to the inside of each service disconnecting means enclosure. The grounding electrode conductor taps shall be sized in accordance with 250.66 for the largest service-entrance conductor serving the individual enclosure. The tap conductors shall be connected to the common grounding electrode conductor by one of the following methods in such a manner that the common grounding electrode conductor remains without a splice or joint:
(1) Exothermic welding.
(2) Connectors listed as grounding and bonding equipment.
....

 

[kwired]

I don't think the connections from the GEC taps to the GEC have to be irreversible. I think most split bolts would suffice.

Maybe. We don't have a service with multiple disconnecting means, we have multiple services, which doesn't exactly fit the topic of your quoted section.

 

[Volta]

Maybe. We don't have a service with multiple disconnecting means, we have multiple services, which doesn't exactly fit the topic of your quoted section.

Well you may be right there. I guess it would come down to grouping. With 230.2, the multiple laterals would be considered to feed one service fo the purposes of 230.40 Ex2, which in turn would require the disconnects to be grouped.

But as the OP is driving 3 rods, I think you are right that they are not likely grouped.

Irreversible it is then! :thumbsup:

 

[kwired]

Well you may be right there. I guess it would come down to grouping. With 230.2, the multiple laterals would be considered to feed one service fo the purposes of 230.40 Ex2, which in turn would require the disconnects to be grouped.

But as the OP is driving 3 rods, I think you are right that they are not likely grouped.

Irreversible it is then! :thumbsup:

My understanding is it is separate services under allowance for multiple occupancies. (230.2(B)(1).

I don't like it when people use this rule but it is there. I also find it hard to believe there is no space for service equipment that is accessible to all occupants on just about all installations using this rule. There is almost always plenty of space on an exterior wall somewhere, and you do see many multi-occupancy buildings that do put exterior meter banks in one location so there is only one service.

First words in 230.2(B) are "by special permission". To me that means one should be involving the AHJ during the design phase of this, and not just installing it without getting special permission first.