jw441
Member
Re-posting/wording of 3-26-06 posting, "Motor Feeder Calcs":
Using 99' NEC, 90degree C THHN CU wire within 50' in RMC - find the wire size required to connect a continuous run, 3 phase, 200 hp synchronous motor into a 480 volt circuit.
My calculations: First, I actually came up with 3 different calcs(#4/0, 250 & 350). I'm missing/overlooking the determinant variable(s)/factor(s) that define one size over another. Prints called for 350s, we RFIed on #4/0(3 - #4/0, 1 - #4 GND in 2" RMC) and it was verbally accepted, but I'm still not convinced on the calc and/or how to word it. Second, a parallel feed(in 2 separate conduits) of the same size wire(as used for 200 hp motor), can be used to connect same at 400 hp... correct?
Any/all input, assistance is greatly appreciated.
Fraternally, jw441
I'd like to apologize for any/all previous mistakes in content and/or etiquette, and hope to change my involvement here, after my two boys are off in the Navy this August - I'm a single parent. No excuses, just humble thanks.
Using 99' NEC, 90degree C THHN CU wire within 50' in RMC - find the wire size required to connect a continuous run, 3 phase, 200 hp synchronous motor into a 480 volt circuit.
My calculations: First, I actually came up with 3 different calcs(#4/0, 250 & 350). I'm missing/overlooking the determinant variable(s)/factor(s) that define one size over another. Prints called for 350s, we RFIed on #4/0(3 - #4/0, 1 - #4 GND in 2" RMC) and it was verbally accepted, but I'm still not convinced on the calc and/or how to word it. Second, a parallel feed(in 2 separate conduits) of the same size wire(as used for 200 hp motor), can be used to connect same at 400 hp... correct?
Any/all input, assistance is greatly appreciated.
Fraternally, jw441
I'd like to apologize for any/all previous mistakes in content and/or etiquette, and hope to change my involvement here, after my two boys are off in the Navy this August - I'm a single parent. No excuses, just humble thanks.