how much can it handle

[clayton]

how exactly would you calculate the current carring capacity of 500mcm cable but with 9conductors, three runs of conduit so 3 paralleled
runs i guess,

looking it up in 310 I see 430 amps, (thhn)

and multiply it times 3, to get 1290, is this then (three phase 480) is this then the total amps per phase with this conductor?


thanks clay.

 

[ryan_618]

Re: how much can it handle

Your question is about ampacity. You are right, that is the ampacity, but remember that 110.14(C) will not let you terminate using the 90 degree values.

 

[tshea]

Re: how much can it handle

I would use the 75 col @ 380 Amps times 3 = 1140A

No need for the 480 in this calculation.
Use 90 col for derating, which is not applicable here as you are using 3 conduits each with 3 wires, for 3 phase power.

 

[ryan_618]

Re: how much can it handle

Please remember to observe the rule found in 240.4(C).

 

[clayton]

Re: how much can it handle

ryan, tshea,

thank you the information you gave me helps alot,

i really appreciate the code references,

sincerely clay