power supply to a tenant meter

[Mr. Bill]

I have a commercial project with multiple tenants. Each tenant has a sub-meter for billing. The EC installed the tenant meters per manufacturer instructions. The Inspector told the EC that it violates the NEC and that he had to add a breaker on the MDP for power to all of the tenant meters.

2,000A, 3-phase service into the building with a single main breaker as the service disconnect. Utility meter outside. Several 400A branch breakers for tenant suites. A 400A sub-meter for each tenant. The sub-meter wiring diagram shows the power for the meter tapped onto the tenant feeder it is metering.

The Inspector required them to add a 15A/3P breaker in the MDP for the sole purpose to power these meters.

I never heard a code section cited by the Inspector. I'm assuming it is related to the tap rule which I have never understood. I have never had this come up on a project before. Most meter diagrams I've found online look similar to this one. Are the manufacturers violating the NEC or is this Inspector mistaken?

 

[jap]

What size is the Overcurrent Protection device labeled L1, L2 and L3 in the Metering Unit ?, how far away is the meter from the load side of the 400a tenant main? , and what size wire did the electrician use to tap the 400 amp feeder top power the meter ?

JAP>

 

[Mr. Bill]

- They are labels as 0.1A.
- The metering is adjacent to the MDP.
- The meter is pre-wired from the factory. It looks small, about 14 AWG. If the wire size was the issue, wouldn't the Inspector have just told him to up the wire to an 8 AWG rather than telling him to add a breaker?

 

[jap]

- They are labels as 0.1A. View attachment 21567
- The metering is adjacent to the MDP.
- The meter is pre-wired from the factory. It looks small, about 14 AWG. If the wire size was the issue, wouldn't the Inspector have just told him to up the wire to an 8 AWG rather than telling him to add a breaker?

Not sure what the installation instructions advise as far as overcurrent protection for the meter, but, not even #8 would be large enough to satisfy the tap rule.

Not sure what authority the inspector had to require the overcurrent protection for it, but, I would agree with him if for nothing more than a common sense standpoint.

I'm surprised the OCP means for the meter was not addressed in the installation instructions.

JAP>