Feeder Cable Sizing Question
Feeder Cable Sizing Question
(OP)
I have a Bus Bar (BB) some 650 feet away from the MCC. The full load on the BB will be 260A. This is 3ph 480V. Would it be more prudent to run a single set of 350MCM conductors (THHN) out to it...or parallel 2 sets of 3/0? This will be in galvenized rigid conduit.
I will also have three other similar setups; however, the loads will be 750ft, 900ft, and 1050ft from the MCC.
I will also have three other similar setups; however, the loads will be 750ft, 900ft, and 1050ft from the MCC.






RE: Feeder Cable Sizing Question
RE: Feeder Cable Sizing Question
RE: Feeder Cable Sizing Question
How about a response.
RE: Feeder Cable Sizing Question
I'm going to use THHN.
Given that 350MCM is good for 350 Amps. I initially chose this size.
I ran through the voltage drop calculation and found that (3) three 350MCM cables with a 2/0G stretched 650" through rigid conduit will have a VD of 3.9% Thus, I will run a 3" conduit and pull (3)-1/C 350MCM with 2/0 ground.
Have I done this correctly?
I should never exceed 5% when dealing with VD, yes?
Thanks for your help guys!
RE: Feeder Cable Sizing Question
RE: Feeder Cable Sizing Question
AS David said, you can not use the 90C rating for ampacity rating. You must use the 75C rating instead. The terminations on your gear are rated at 75C. You can not use 350 THHN. You need 500 kcm. Lucky we caught this.
RE: Feeder Cable Sizing Question
Bill
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"Why not the best?"
Jimmy Carter
RE: Feeder Cable Sizing Question
What do you think?
RE: Feeder Cable Sizing Question
RE: Feeder Cable Sizing Question
RE: Feeder Cable Sizing Question
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