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Joined: Apr 2003
Posts: 362
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Hi Guys, I am doing a 600a 1phase service and I was going to use 350kmcm in parallel, my friend from a diffrent firm is telling me they used 300kmcm for one just recently. Now I am second guessing myself, so I am turning to you all.


Ob


Choose your customers, don't let them choose you.
Joined: Apr 2002
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300KCMil Copper, 75 degree col is 285 amps,Based on 240.4 (B)parallel is 570 amps, next higher available is 600 amps.

300's work.


John
Joined: Mar 2003
Posts: 849
Y
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If in two seperate conduits 300 kcmil is good for 285 amps at 75c. see 240.4 (b) (800 amps or less next higest breaker size) .
240.6 300 next breaker size is 600.
285 plus 285 = 570
if in one single conduit see table 310.15(B)(2)(a)
4-6 80%
570x80%=456 next higest per 240.6= 500amp.
Same Conduit would require 400 Kcmil
335x2= 670 x 80%= 536 . 240.6 next higest 600
This is with 3 wires in conduit single phase. Or
6 wires in conduit single phase.


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