kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I was not aware of this change or the similar changes in 210.19 and 215.2, and it was a change to 2014 NEC and here we are getting close to 2020 being released.
Commentary at 215.2 that is part of my 2014 E-book edition finally cleared up what I was not grasping, it says:
This is what most of us have always been doing for branch circuits and feeders all along.
2011 didn't mention "before application of any adjustment or correction factors" in 230, but did say this in 210 and 215, so the change mostly affected service conductors.
Otherwise before this change we always have figured two conductor sizes, especially for branch circuits and feeders. One was generally for a 75C conductor for termination rating, figured at 125% of continuous load plus 100% of non continuous load. The second one was generally for a 90C conductor (that is mostly insulation type we use) at 100% of continuous and non continuous load with any necessary corrections/adjustments that may apply. This second calculation was for insulation ampacity so 100% of load is all that mattered, terminations are what need 125% for continuous loads unless a 100% rated device, but apparently someone didn't think it was clear enough before and had things re-written. Then you selected whichever result yielded the larger conductor - which is still exactly what you end up doing.
Commentary at 215.2 that is part of my 2014 E-book edition finally cleared up what I was not grasping, it says:
This is what most of us have always been doing for branch circuits and feeders all along.
2011 didn't mention "before application of any adjustment or correction factors" in 230, but did say this in 210 and 215, so the change mostly affected service conductors.
Otherwise before this change we always have figured two conductor sizes, especially for branch circuits and feeders. One was generally for a 75C conductor for termination rating, figured at 125% of continuous load plus 100% of non continuous load. The second one was generally for a 90C conductor (that is mostly insulation type we use) at 100% of continuous and non continuous load with any necessary corrections/adjustments that may apply. This second calculation was for insulation ampacity so 100% of load is all that mattered, terminations are what need 125% for continuous loads unless a 100% rated device, but apparently someone didn't think it was clear enough before and had things re-written. Then you selected whichever result yielded the larger conductor - which is still exactly what you end up doing.