Complex Imaginary Test 1 Problem 26

[forest]

How do you get the answer? I saw 240A on the table not 190A.

Thank you

 

[forest]

Just ignore my question, I have found the answer.

Thank you

 

[Lucy99]

I was confused on this question and the solution. Are we looking for a current rating for the conductor( which I understand is 190A) or are we sizing the OC device?

The solutions mention the breaker being sized to equal or less than the conductor ampacity. However, NEC 2008 240.4(B) says devices under 800 amps "the next higher standard OC device rating shall be permitted.....if the ampacity of the conductors does not correspond with the standard ampere rating of a fuse or circuit breaker" and the next standard size breaker is 200amps. This question is asking for the "largest allowable" i.e. MAXIMUM allowed which is also why we wouldn't size the OC device down...

Any help would be appreciated.

 

[stbtigerr]

This is question 69 in the newer edition. I had the same question and e-mailed Complex Imaginary. Their explanation was that since they didn't specify any of the conditions in 240.4(B'), you can't use that rule.