AJElectric
Member
- Location
- Iowa
We do a lot of (mostly) agricultural wiring so we commonly encounter a scenario where there is a POCO pole or pad-mount transformer with 200A 120/240V 1ph meter loop or CT metering on premises (farm yard with residence and outbuildings) and from there splitting off to feed separate buildings.
Back in the day, the standard procedure was GE bonded to N at the service disconnect for premises, and then OH or USE wire to each structure without including a ECG or GEC. At "service entrance" for each building is a GE bonded to N and appropriate main w/ OCP. Most of these drops would range from 30 to 100A.
20 years later, as many of these yard's services are being upgraded to accommodate new buildings, heavier loads, adding standby generator, etc. typically a new proper service disconnect with OCP and/or MDP is installed near POCO trans with GE bonded to N and comprises the "main service" for the premises - everything downstream being treated as a feeder and 4-wire service (L,L,N,ECG) routed to new structures.
Regarding _existing_ feeders off this new main service the question is always "What to do about the lack of ECG from bonding point at main service???" Common practice has been to leave it as-is and leave the N bonded at each structure (remember no ECG exists back to POCO trans) with existing GE in place, with the assumption that the GE "sort of" takes the place of ECG. (In other words, no one wanted the expense of adding a ECG to every building which has been there 50 years and "didn't need one" before).
It should go without saying that the GE at each building does not take the place of the EGC, and a loose main neutral would present a shock hazard in spite of the GE bonded to N (and it HAD been that way for 50 years). So for me this begs the question - on a new installation where a 4-wire feeder is run to the building, why _is_ a GE required there?
Back in the day, the standard procedure was GE bonded to N at the service disconnect for premises, and then OH or USE wire to each structure without including a ECG or GEC. At "service entrance" for each building is a GE bonded to N and appropriate main w/ OCP. Most of these drops would range from 30 to 100A.
20 years later, as many of these yard's services are being upgraded to accommodate new buildings, heavier loads, adding standby generator, etc. typically a new proper service disconnect with OCP and/or MDP is installed near POCO trans with GE bonded to N and comprises the "main service" for the premises - everything downstream being treated as a feeder and 4-wire service (L,L,N,ECG) routed to new structures.
Regarding _existing_ feeders off this new main service the question is always "What to do about the lack of ECG from bonding point at main service???" Common practice has been to leave it as-is and leave the N bonded at each structure (remember no ECG exists back to POCO trans) with existing GE in place, with the assumption that the GE "sort of" takes the place of ECG. (In other words, no one wanted the expense of adding a ECG to every building which has been there 50 years and "didn't need one" before).
It should go without saying that the GE at each building does not take the place of the EGC, and a loose main neutral would present a shock hazard in spite of the GE bonded to N (and it HAD been that way for 50 years). So for me this begs the question - on a new installation where a 4-wire feeder is run to the building, why _is_ a GE required there?