Making the mistake of not fully understanding this section of the NEC, i completed the wire install of an ATS. With startup coming soon, i ask our city inspector to review my bonding of the underground raceways coming up into an open enclosure, consisting of pvc with rigid nipple's thru the pad.
He failed my install stating that the bond bushings had too small of a ground wire running thru them, based on section 250.122
Here's the details, this is a 3000 amp ATS with 3000 amp OCPD's wired with, all phases, neutral and ground are 700 KCM AL. wire, paralelled 8 sets.
I believe that i satisfied the requirements of section 250.122 with the 700 KCM grounding conductor (which is over sized 100KCM), in each conduit.
This my understanding of the requirements for bonding the raceways per section 250.102(c) and 250.66 using a conductor no less than 12 1/2 percent of of the area of the largest phase conductor...
700,000 x .125 = 87,500 cir. mils , rounding up to 105,600 cir. mils @ 1/0 AWG
size CU. bonding conductor at each conduit.
I have a considerable amount of rework as it is correcting this mistake, adding a 400 KCM to 16 underground 4" conduits bond bushings, per the inspectors interpetation of applying section, 250.122 and not 250.102(c).
Any advice and or ammunition would be greatly appreciated, Erik
He failed my install stating that the bond bushings had too small of a ground wire running thru them, based on section 250.122
Here's the details, this is a 3000 amp ATS with 3000 amp OCPD's wired with, all phases, neutral and ground are 700 KCM AL. wire, paralelled 8 sets.
I believe that i satisfied the requirements of section 250.122 with the 700 KCM grounding conductor (which is over sized 100KCM), in each conduit.
This my understanding of the requirements for bonding the raceways per section 250.102(c) and 250.66 using a conductor no less than 12 1/2 percent of of the area of the largest phase conductor...
700,000 x .125 = 87,500 cir. mils , rounding up to 105,600 cir. mils @ 1/0 AWG
size CU. bonding conductor at each conduit.
I have a considerable amount of rework as it is correcting this mistake, adding a 400 KCM to 16 underground 4" conduits bond bushings, per the inspectors interpetation of applying section, 250.122 and not 250.102(c).
Any advice and or ammunition would be greatly appreciated, Erik