jar546
CBO
For the purpose of keeping things simpler, let's stick with the 2014 or 2017 NEC and whatever applicable IRC Electrical section applies that is taken from those years. Also, everything is assumed to be copper.
OK, so the grounding electrode conductor (GEC) is sized per 250.66, the load size equipment grounding conductor (EGC) is sized per 250.122 and both have been for many code cycles. Recently, under Part V "Bonding" a table has been added to 250.102.
If you have a 200A service on a dwelling fed with 3/0 copper, the GEC per 250.66 is required to be #4awg copper. If, from that main panel with the disconnect you were going to run a 100A sub-panel with #3awg copper, the EGC would have to be a minimum of a #8awg copper as per 250.122. I think we should all agree that this is what the code calls for. With that in mind, here is the question:
If you have an 18kw standby generator (rated at 75A) with a 100A OCPD on the generator feeding a newly installed non-service rated automatic transfer switch (ATS), where the load size of the 200A service disconnect feeds the normal lugs of the ATS enclosure and the load side of the ATS feeds to the load that was originally fed by the load side of the service disconnect have all of those conductors fed through a common conduit (PVC nipple), what size does the EGC need to be that bonds the service disconnect to the ATS?
Please give us the answer and what NEC section/table you used.
Enjoy!
OK, so the grounding electrode conductor (GEC) is sized per 250.66, the load size equipment grounding conductor (EGC) is sized per 250.122 and both have been for many code cycles. Recently, under Part V "Bonding" a table has been added to 250.102.
If you have a 200A service on a dwelling fed with 3/0 copper, the GEC per 250.66 is required to be #4awg copper. If, from that main panel with the disconnect you were going to run a 100A sub-panel with #3awg copper, the EGC would have to be a minimum of a #8awg copper as per 250.122. I think we should all agree that this is what the code calls for. With that in mind, here is the question:
If you have an 18kw standby generator (rated at 75A) with a 100A OCPD on the generator feeding a newly installed non-service rated automatic transfer switch (ATS), where the load size of the 200A service disconnect feeds the normal lugs of the ATS enclosure and the load side of the ATS feeds to the load that was originally fed by the load side of the service disconnect have all of those conductors fed through a common conduit (PVC nipple), what size does the EGC need to be that bonds the service disconnect to the ATS?
Please give us the answer and what NEC section/table you used.
Enjoy!