Main bonding jumper splice

[lpfam11]

We have an inspector here who is calling us out on our ground loop system. We build power equipment buildings which get shipped to their destination. Sometimes, these have to be built in sections and split apart to ship. Thsi is the case on this particular project.

We provide a ground pad on the outside of our building. We run a 4/0 ground from there up to our 1/4" x 2" ground bar loop. This loop runs all the way around the inside of the building. Each individual piece of equipment's ground runs to that ground loop.

When we have split buildings like this one, we run the bar up to the split on both sides then install a 4/0 bare jumper across the split which can be removed for shipping and reinstalled in the field. He is saying that we cannot do this according to 250.24 because the main bonding jumper (the 1/4" x 2" copper loop in this case)must be unspliced. He went on to say that if it is spliced, it must be connected by cad welding it. Is this the case or are you allowed connecting by any other means such as those listed in 250.8?

 

[mike7330]

Is this a cell tower building? The ones I did in the past had a grounding system inside the building and a halo. Are you sure the inspector understands what this ground system is for? You do need a unspliced main bonding jumper for the service disconnect! I hope this is what you asking?

 

[bphgravity]

As mike has indicated, I think the inspector is a little confused. The grounding/bonding system you are describing is not a component of the premises wiring system (SERVICE) & the splice you are describing is certainly not the main bonding jumper referenced in the section cited by the inspector or even a main bonding jumper by definition.

Unless your construction documents have engineered detail specifying how splices are to be made in the grounding system you are installing, the inspector has no justification for rejecting your installation as described.

 

[qcroanoke]

As mike has indicated, I think the inspector is a little confused. The grounding/bonding system you are describing is not a component of the premises wiring system (SERVICE) & the splice you are describing is certainly not the main bonding jumper referenced in the section cited by the inspector or even a main bonding jumper by definition.

Unless your construction documents have engineered detail specifying how splices are to be made in the grounding system you are installing, the inspector has no justification for rejecting your installation as described.

Bryan is correct.
What did he say about the splices you made after the buss ran out? We use copper in 12 ft lenghts and then bolt them together.
It sounds like you are on a POCO sub-station site and the local has no authority there. (unless invited).

 

[SG-1]

Why not just supply a short section of bus bar, or is the dimension too variable ?

If I remember correctly a 1/4 by 2 ground bus is equal to a 500kcmil cable.

 

[Smart $]

First, I have to ask, are your "buildings" listed assemblies?

If so, that's a plus... but while many believe an inspector or AHJ has no jurisdiction on listed parts or assemblies, they are wrong. Code specifically says all equipment used must be approved... and the AHJ is the entity which does the approving.

Though he cited the wrong section, I have to agree with the inspector. The issue here, which is dependent on the service disconnect being located in your power equipment building, is that the grounding electrode conductor is not continuous or as provisionally excepted per 250.64(C). As SG-1 suggested, busbar jumpers fall within the provisioned exceptions.... but you will still have to contend with any other wire-to-busbar connections in the GES.

 

[lpfam11]

Thank you for everyone's reply. A lot of the buildings we manufactire are UL listed. This particular one is not, however, we do the ground loop the same in all buildings and UL inspectors have never had an issue with it. Yesterday evening, we were able to come to a resolution with the inspector by changing out the 4/0 bare jumpers with 1/4x2 bar jumpers. He accepted this and we will move on from it but I would still like to understand this more. In my mind, whether we install a 4/0 jumper or a bar jumper, it is still a splice. The switchgear buildings we do can get very large and as someone mentioned above we use 12' sections of copper bar, and it is impossible to install one continuous ground loop in them without splicing them. Why is splicing with bar ok and splicing with cable not ok as long as you use the approved mechanical connections. I have yet to find the section he says states that if you do splice, it has to be with exothermic welding.

 

[qcroanoke]

Why is splicing with bar ok and splicing with cable not ok as long as you use the approved mechanical connections. I have yet to find the section he says states that if you do splice, it has to be with exothermic welding.

250-64 (C) is what he is using. but he is wrong. what you are doing is not the grounding electrode conductor. IMO

 

[eprice]

We provide a ground pad on the outside of our building. We run a 4/0 ground from there up to our 1/4" x 2" ground bar loop. This loop runs all the way around the inside of the building. Each individual piece of equipment's ground runs to that ground loop.

A couple of questions, just to make sure I'm looking at this correctly:

1) Are there other grounding electrode(s) for the building and is this ground pad bonded to the grounding electrode system?

2) Is the grounding of individual pieces of equipment that you mention in addition to the equipment grounding conductors run with the circuits supplying power to the equipment, or does the ground loop take the place of equipment grounding conductors run with the supply circuits?

 

[Smart $]

250-64 (C) is what he is using. but he is wrong. what you are doing is not the grounding electrode conductor. IMO

If the service disconnecting means is located in the "building" and this bus provides the only low-resistance pathway to earthing electrodes, how is it not the GEC???

 

[mike7330]

250-64 (C) is what he is using. but he is wrong. what you are doing is not the grounding electrode conductor. IMO

Correct!!!!

 

[qcroanoke]

Nevermind.