The size of overcurrent protective device required for a 645 Amp load is?
I chose 600A. The choices were 600A or 700A. The correct answer was 700 Amps. According to the NEC 240.6 Standard Ampere Rating (A) Fuses and Fixed - Fixed-Trip Circuit Breakers there was both 600 and 700 included. Why would I chose 700A overcurrent protection when the load is 645 AMP.
The Amp Load is being feed using 6 parallel Aluminum (THHN) conductors size #1 AWG. According to Table 310.16, the max current per conductor is 115 Amps, So 6 X115A = 690 Amps. This is less than 700 Amps. Not sure why the 700Amps protection is chosen instead of the 600 Amp protection. I do not see in the NEC where they allow you to insert a higher standard fuse rating or maybe I am missing something?
I chose 600A. The choices were 600A or 700A. The correct answer was 700 Amps. According to the NEC 240.6 Standard Ampere Rating (A) Fuses and Fixed - Fixed-Trip Circuit Breakers there was both 600 and 700 included. Why would I chose 700A overcurrent protection when the load is 645 AMP.
The Amp Load is being feed using 6 parallel Aluminum (THHN) conductors size #1 AWG. According to Table 310.16, the max current per conductor is 115 Amps, So 6 X115A = 690 Amps. This is less than 700 Amps. Not sure why the 700Amps protection is chosen instead of the 600 Amp protection. I do not see in the NEC where they allow you to insert a higher standard fuse rating or maybe I am missing something?