*Commercial Lease Space Grounding*

[Jdoyle]

We have a lease space, with a 10ft gutter with tap box. When the shell was built, the concrete encased electrode and ground rod were connected to a grounding busbar in the tap box. Now we have multiple tenants installing their services, and the utility provider wont let them connect their grounds for each service to the grounding busbar in the tap box. We are not getting clarification from the utility provider as to why, and we are looking for answers as to where each service should be pulling their service grounding conductors from.

 

[david]

Are the tenant services grouped at one location?

Are you talking about building steel or main water as grounding electrodes?

 

[Jdoyle]

All the services are grouped at the 10 ft gutter. There is a concrete encased electrode and a ground rod that have GECs that connect to a ground busbar in the tap box at the end of the gutter. When we inspected the services we had the electricians run the grounds from the service disconnect after the meter to the ground busbar. The utility provider had them remove the grounds from the service disconnects. So now we have an ungrounded service. Or so I think we do.

 

[jaggedben]

The description is confusing. I'm gathering you don't actually mean multiple services, but rather a single service brought to the tap box, from which tenants (presumably not more than 6) are tapping off to install separate service disconnects.

The NEC would allow you to ground the grounded conductor (neutral) in the tap box in order to ground the service. That means you would connect the GECs directly to the neutral bar in the tap box. Landing on a separate ground bar isn't the way.

If the utility isn't allowing that for some stupid reason (but it's unclear to me if that's the problem) then you could, alternatively, irreversibly splice the rod and Ufer GECs to a GEC sized to 250.66, and run that GEC to a location where a GEC from each service disconnect can tap on to it (say, with a Kerney bolt).

What is your 'ground bar' in the tap box connected to? Is the grounded conductor bonded to the tap box inside it?

One doesn't ordinarily 'run grounds' on the line side of service disconnects. The grounded conductor is the fault return path there.

 

[Jdoyle]

There will be 6 meters being fed from the gutter, then each meter will have a fused disconnect after the meter. When the shell was built before each tenant came in, the main gutter had the grounding electrods connected to a ground busbar in the gutter/tapbox. As each tenant is beginning their individual build outs, we are noticing that the utility provider is making them pull out the grounds from the busbar in the gutter/tapbox. But when this is done, there is now no grounding for each service. Each first means of disconnect has the neutrals and grounds bonded. The electricians are now confused as to where to get the grounds from.

 

[jaggedben]

Again, the NEC allows you to ground the service in the tap box. You seem to be confusing grounding and bonding.

What is your 'ground bar' in the tap box connected to? Is the grounded conductor (neutral) bonded to the tap box or gutter?

 

[david]

From your posting you said you did the inspection, the utility requlations should state if grounding electrode conductors are not allowed in equipment that the utility is sealing.

The tap box would be a common location for all the service disconnects, if so you would expect to only see one grounding electrode conductor from that location to a concrete encased electrode, and one GEC to the ground rods you mentioned.

If the utility is not allowing that you could talk to the electrician about installing a copper bussbar and installing your GEC to that bussbar

Install GEC from your individual service disconnects to the copper bussbar.

There are other options using a common grounding electrode conductor and taps.

As a note I never herd of a utility unwilling to talk to an inspector about one of their requlations

 

[gene6]

It sounds like this 'gutter' is a sealed inaccessible service end box. And what the utility may call multiple services the NEC calls one service, remember meters don't make a service.
Here that ground bar would not be allowed in that 'gutter' it would be mounted on the wall under the disconnects. the only bonding in that 'gutter' would be the neutral to the gutter.
See 250.24
There was a long discussion about this earlier this year:

Bonding neutral and ground at service end box in NYC

Hold on a second... How and why are they accepted on services if there is objectional current? isn't objectional current forbidden by code? One the line side of the main disco, the neutral and any metallic enclosures and raceways are considered to be the same conductor.

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