test tomorrow, studying late, one question driving me crazy!

[bekahhren]

OK so I'm taking the exam tomorrow morning and this one two part practice question is driving me CRAZY!
Here it is:
1) Conductor "A" has a continuous load of 208 Amps.
What is the minimum standard size fuse required to protect Conductor A?
208x1.25 = 260, next standard size is 300 amps

So far so good, the practice test answer is 300 amps

2) Equipment terminations are 75 degree C, Type THHN copper conductors in conduit are to be used. minimum allowable size of ungrounded conductor in the feeder is?
So - 300 amp fuse, go to 310.16, check down the 75 degree column, the answer is 350 kcmil. BUT the test says the answer is 300kcmil, which would work with THHN... but, I know I'm supposed to use the 75 degree c ampacity ratings if that is the equipment termination!

What am I missing here? I can't figure it out!!

 

[charlie b]

Excellent question. The answer is that you only have to size the conductor for the load, not for the overcurrent device. The load (adjusted for being a continuous load) is 260 amps. The smallest conductor with that ampacity is 300 MCM.

Best of luck on the test.