First time posting here, this forum has been a great help as I develop my understanding of NEC codes. I've tried searching but haven't been able to find anything relevant.
California recently went on the 2020 NEC code cycle, and I noticed 705.12(B)(3)(5) which I have not been able to find any discussions on. (1) - (4) are the same backfeed rules as the 2017 cycle, I saw a great writeup by Mayfield on (6), but to me (5) is the interesting one.
"Connections shall be permitted on switchgear, switch-boards, and panelboards in configurations other than those permitted in 705.12(B)(3)(1) through (B)(3)(4) where designed under engineering supervision that includes available fault-current and busbar load calculations."
I'm reading that as long as an electrical engineer stamps off on the panel, we can exceed the 120% rule if we have a load calc and the available fault current. Is that correct? If so, this seems like the fabled "150% rule" that has been discussed for a few years. I can see why the rules comittee would rather have an EE sign off rather than a blanket 150% rule.
Has anyone used 705.12(B)(3)(5) to exceed 120% on a project? If so, where there any challenges to getting the project approved? Is getting the "available fault current" a hassle?
Getting main panel upgrades done in California has been challenging in recent years with the updated utility requirements resulting in relocations, feeder line upgrades, wait times in the months to move things forward, high cost of the electrical work, etc. It would be wonderful to have another code in my backpocket for more troublesome projects.
If I'm completely misinterpreting the code, I'd greatly appreciate any corrections.
California recently went on the 2020 NEC code cycle, and I noticed 705.12(B)(3)(5) which I have not been able to find any discussions on. (1) - (4) are the same backfeed rules as the 2017 cycle, I saw a great writeup by Mayfield on (6), but to me (5) is the interesting one.
"Connections shall be permitted on switchgear, switch-boards, and panelboards in configurations other than those permitted in 705.12(B)(3)(1) through (B)(3)(4) where designed under engineering supervision that includes available fault-current and busbar load calculations."
I'm reading that as long as an electrical engineer stamps off on the panel, we can exceed the 120% rule if we have a load calc and the available fault current. Is that correct? If so, this seems like the fabled "150% rule" that has been discussed for a few years. I can see why the rules comittee would rather have an EE sign off rather than a blanket 150% rule.
Has anyone used 705.12(B)(3)(5) to exceed 120% on a project? If so, where there any challenges to getting the project approved? Is getting the "available fault current" a hassle?
Getting main panel upgrades done in California has been challenging in recent years with the updated utility requirements resulting in relocations, feeder line upgrades, wait times in the months to move things forward, high cost of the electrical work, etc. It would be wonderful to have another code in my backpocket for more troublesome projects.
If I'm completely misinterpreting the code, I'd greatly appreciate any corrections.