Mike Dolt Enterprises
Mike Dolt Enterprises
User: nspctr, Location: Florida
Asked on: Tuesday, April 19, 2011 at 9:11 am EDT
Answered on: Tuesday, May 14, 2024 at 4:23 am EDT
Question: on a multi tennant building with more than six mains, a main ahead is required. when a main is ahead of the tennant meters , and the grounding conductor with the feeder is pulled through the meter enclosures, (unbroken) to the tennant disconnect. is the meter enclosure required by the code to be isolated by PVC, as the neutral conductor is again bonded to the enclosure.?.we are having quite a discussion about this topic.
NEC Requirement
NEC 250.24(A)(5) requires that the grounded conductor (neutral) be bonded to the enclosure of the meter. However, it does not specify that the enclosure must be isolated from the grounding electrode conductor (GEC).
Grounding Electrode Conductor (GEC)
The GEC is an unspliced conductor that connects the electrical system to the grounding electrode (e.g., water pipe, grounding rod). It typically enters the meter enclosure from the outside and is bonded to the enclosure through a main bonding jumper (MBJ). The GEC provides a low-impedance path for fault currents to return to the source.
Isolated Meter Enclosure
In the scenario you described, the meter enclosure is not isolated by PVC. The GEC is pulled through the enclosure to the tenant disconnect, which means it is still connected to the enclosure. This is permitted by NEC 250.24(A)(5), which does not require isolation of the enclosure.
Rationale
The purpose of the enclosure is to provide protection for the meter and wiring. The GEC's connection to the enclosure ensures that fault currents can flow to the grounding electrode without compromising the safety of the meter or occupants. Isolating the enclosure would create a discontinuity in the GEC's path, which could result in a hazardous situation.
Conclusion
Based on the NEC requirements, the meter enclosure in your scenario is not required to be isolated by PVC, as the GEC is pulled through the enclosure and bonded to it. This configuration complies with NEC 250.24(A)(5) and ensures proper grounding of the electrical system. Flag for review