cdcengineer
Senior Member
In referring to table 310.16 (now 310.15(B)(16) - how dare the code council change this on us), I have always used the 75 C column when calculating the max ampacity of conductors (when over 100A). However, when it comes to dollars and cents we're asked to look as hard as possible for ways to save money while meeting the intent of the code.
I notice that 500MCM XHHW CU is good for 380A & 430A at 75C & 90 C respectively. I would normally run 1200A feeder in 4 sets of 350 CU.
NEC 240.4 requires that for MOCP devices over 800A, the conductor be rated at or above that of the overcurrent protection device.
The question - we are running feeders through a parking garage, in a dry environment (re: table 310.104(A)), and they want to run (3) sets of 500MCM CU. Anyone have any issues with this?
I have never used the 90 C column, although I know it's there for a reason.
As always, input is greatly appreciated.
I notice that 500MCM XHHW CU is good for 380A & 430A at 75C & 90 C respectively. I would normally run 1200A feeder in 4 sets of 350 CU.
NEC 240.4 requires that for MOCP devices over 800A, the conductor be rated at or above that of the overcurrent protection device.
The question - we are running feeders through a parking garage, in a dry environment (re: table 310.104(A)), and they want to run (3) sets of 500MCM CU. Anyone have any issues with this?
I have never used the 90 C column, although I know it's there for a reason.
As always, input is greatly appreciated.