I am a junior electrical engineer. I have to parallel 4 ? core 500ckmil size cables for a 2000A main breaker. The supply voltage is 415Y/230V which consists of 3 phases, a neutral and an earth. Each cable is to be installed a 4? conduit which is buried at 24? below the ground level. I have use table 310.16 to calculate the ampacity of the cables, using the following assumption:
? ambient temperature of30oC
? Termination rated at 75oC
? The cable is THHN/THWN rated @ 75oC.
From this table, 1No. 4 ? core 500ckmil cable has the ampacity of 380 which then gives a total of 6No. 4 ? core 500ckmil cable for the 2000A main.
Is this table the correct table to use for this type of installation or should I be using table 310.6 in Annex B?
Do I have to derate the cable for 4 current carrying conductors give that the system is a 415Y/230V 3 phase with neutral?
? ambient temperature of30oC
? Termination rated at 75oC
? The cable is THHN/THWN rated @ 75oC.
From this table, 1No. 4 ? core 500ckmil cable has the ampacity of 380 which then gives a total of 6No. 4 ? core 500ckmil cable for the 2000A main.
Is this table the correct table to use for this type of installation or should I be using table 310.6 in Annex B?
Do I have to derate the cable for 4 current carrying conductors give that the system is a 415Y/230V 3 phase with neutral?