Kevin F
New User
- Location
- Tallahassee, FL
- Occupation
- EE
(NEC 2017) Working to repair an installation damaged by short circuit/fire. The gear is an exterior meter center, 800amp MCB supplying six 200 amp 3ph service feeders with kwh meter and circuit breaker disconnect, pretty common SqD meter center. The meter center is ruined and replacement is months out at best. We temp'd a CT/meter installation utility side of the 800A main, and tapped in the six service feeders through fused switches.
Customer wants circuit breakers as permanent fix and does not want to return to individual meters. The service feeders are 4 wire with 250.52 grounding and the system BJ at each of 6 panelboards. If I understand, 250.32 Exception 1 permits the grounded conductor to be used as the fault return path where the conditions are met. Also I'm concerned that there is opportunity to create a second N-G connection within the exterior feeder panel. However, as there is no direct GEC between the feeder panel and the customer's service panel, this seems to be a non-issue.
The existing 800 amp main and all new permanent equipment would be bonded by raceway and EGC. The installer bonded the service neutral and the GEC in the main during the repair. It seems that this bond should be removed, and that there could (should?) be no bj between the neutral and ground in the proposed service panel, and then the MCB and individual feeder breakers all become part of the service equipment. However as I stated above I can't see an issue with it as it goes back to the transformer anyway. What am I missing?
K
Customer wants circuit breakers as permanent fix and does not want to return to individual meters. The service feeders are 4 wire with 250.52 grounding and the system BJ at each of 6 panelboards. If I understand, 250.32 Exception 1 permits the grounded conductor to be used as the fault return path where the conditions are met. Also I'm concerned that there is opportunity to create a second N-G connection within the exterior feeder panel. However, as there is no direct GEC between the feeder panel and the customer's service panel, this seems to be a non-issue.
The existing 800 amp main and all new permanent equipment would be bonded by raceway and EGC. The installer bonded the service neutral and the GEC in the main during the repair. It seems that this bond should be removed, and that there could (should?) be no bj between the neutral and ground in the proposed service panel, and then the MCB and individual feeder breakers all become part of the service equipment. However as I stated above I can't see an issue with it as it goes back to the transformer anyway. What am I missing?
K
