Ground and Neutral bonding at a service

[Electricmike]

I am currently at a facility that provides electrical utility to about 250 customers. Most Customers are on a 3 phase 4 wire wye system. This infrastructure was built and designed back in 1969. There are about 11 substations at this facility stepping voltage down from 4160 to208/120, 3 phase. All the substations XFMRs neutral lines has been bonded tobuilding steel and a ground ring, all existing meter bases has the neutrallanded on the neutral bar in the meter base which is bonded to the metal enclosure of the meter base. A ground wire is also landed on the ground terminal of the meter base. A new inspector has started inspecting all new services at this facility. He raised a flag of bonding the ground and neutral at the meter base and XFMR at the substation. They did not want to void the UL listing of the meter base by floating the neutral in the meter base. His answer was to not ground the meter base run Plastic PVC in and out of the meter base to keep it isolated from building steel and the main panel. The meter bases do not come with any kind of isolated neutral bar or kit. Now you have a meter base that is not bonded to building steel. Is this the best solution? Could the way it has been for 40 yrs. stay through a grandfather act somehow? The infrastructure has had its share of faults in its time and worked. I understand where the inspector is coming from but I want to make sure his solution is the best answer?

Thanks for your help

 

[Dennis Alwon]

Why is there a neutral and an equipment grounding conductor run to the meter. If there needs to be then the neutral must not be attached to the can and must have an isolated bay. I believe there are meter bases made for that purpose.

 

[Smart $]

Need to know what Code applies here. You make it sound like the installation is under NEC purview, but just as easily could be under NESC. What authority does this inspector represent, and to which Code is he making his evaluations?


Welcome to the forum :thumbsup:

 

[Electricmike]

I am currently at a facility that provides electrical utility to about 250 customers. Most Customers are on a 3 phase 4 wire wye system. This infrastructure was built and designed back in 1969. There are about 11 substations at this facility stepping voltage down from 4160 to208/120, 3 phase. All the substations XFMRs neutral lines has been bonded tobuilding steel and a ground ring, all existing meter bases has the neutrallanded on the neutral bar in the meter base which is bonded to the metal enclosure of the meter base. A ground wire is also landed on the ground terminal of the meter base. A new inspector has started inspecting all new services at this facility. He raised a flag of bonding the ground and neutral at the meter base and XFMR at the substation. They did not want to void the UL listing of the meter base by floating the neutral in the meter base. His answer was to not ground the meter base run Plastic PVC in and out of the meter base to keep it isolated from building steel and the main panel. The meter bases do not come with any kind of isolated neutral bar or kit. Now you have a meter base that is not bonded to building steel. Is this the best solution? Could the way it has been for 40 yrs. stay through a grandfather act somehow? The infrastructure has had its share of faults in its time and worked. I understand where the inspector is coming from but I want to make sure his solution is the best answer?

Thanks for your help

I have checked into the meter manufacture and they do not sell a isolated neutral kit for their meter base, which has been used for 40 years and has been working great.

The inspector is using the NEC.

 

[Smart $]

I have checked into the meter manufacture and they do not sell a bonding kit for their meter base, which has been used for 40 years and has been working great.

If the neutral is bonded to the enclosure, a bonding kit is not what you need. To satisfy the inspector you'd have to isolate the neutral from the enclosure and any other connection to ground.

The inspector is using the NEC.

The question is whether the NEC is the appropriate Code. Your installation sounds more like a small cooperative. A cooperative can be considered a electric utility under state law.

Ultimately, the question that needs answered:

Where are the premises service disconnecting means located in relation to these meters, before or after?

 

[Electricmike]

If the neutral is bonded to the enclosure, a bonding kit is not what you need. To satisfy the inspector you'd have to isolate the neutral from the enclosure and any other connection to ground.



The question is whether the NEC is the appropriate Code. Your installation sounds more like a small cooperative. A cooperative can be considered a electric utility under state law.

Ultimately, the question that needs answered:

Where are the premises service disconnecting means located in relation to these meters, before or after?

The disconnecting means is before the meter. Back when it was built they needed generators to feed power. The local utility could not feed the system until about mid to late 70s. They then built a substation and is feeding the system to date. The generators output was 4160v.

 

[GoldDigger]

The disconnecting means is before the meter. Back when it was built they needed generators to feed power. The local utility could not feed the system until about mid to late 70s. They then built a substation and is feeding the system to date. The generators output was 4160v.

Even though the ultimate power source is now a POCO instead of owned generators, I think that the fact that you distribute the power to multiple properties and bill them individually is enough to make you a utility under the applicable rules. Hence NESC rather than NEC. The engineering concerns are certainly closer to a utility situation than a customer-owned substation would be.

 

[Smart $]

Even though the ultimate power source is now a POCO instead of owned generators, I think that the fact that you distribute the power to multiple properties and bill them individually is enough to make you a utility under the applicable rules. Hence NESC rather than NEC. The engineering concerns are certainly closer to a utility situation than a customer-owned substation would be.

I agree. That's why I brought up the issue of it possibly being a cooperative and whether it legally being a utility facility. We have to consider the legal side of the situation to make the proper recommendation. Just because the inspector is inspecting to NEC requirements doesn't ensure me that it falls under NEC purview.

If it does fall under NEC purview, and the meters are located on the load side of the service or separately derived system disconnecting means, we can proceed to the requirements of 250.142(B) Exception 2....