motor branch circuit conductors

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electricalperson

electricalperson

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massachusetts
when sizing the branch circuit conductors i know you follow article 430 partXIV to find the FLC. multiply by 1.25 and thasts the branch circuit conductor ampacity. does the rules of article 240.D1-7 apply? if i have a number such as 30 amps can i use 12 awg for example? or 8 awg for a 35 amp load or can i use number 10 since its rated for 35 amps at 75 degrees?
 
You will notice in 240.2(D) that it allows 240.2(G) to apply (not withstanding temperature and other correction factors).
110.14 woul probably not alow you to use #12 at 30 amps, but #10 at 35 would be allowable.
 
my question is, do i have to follow those code rules in article 240.4D1-7 with small conductors? if my calculation of the FLC plus 125% comes out to 33 amps lets say, do i have to use a number 8 or do those rules not apply and i can use the ampacities listed in 310.16. 10 thhn at 75c is rated for 35 amps yet 240.4D7 says i can only protect it at 30 amps
 
read 240.4 (D)... "unless pemitted in 240(G) ....
240(G) negates 240(D)(7)
 
Find the FLA, multiply by 125% and look up the resultant ampacity in 310.16. For a #10 THHN in a raceway the ampacity is 35 amps @ 75 degrees C. As long as all of your terminations are rated for 75 degrees the #10 conductor can be used at it's 75 degree ampacity of 35 amps.
 
im doing the motor and ac section in mike holts nec prep book for my masters class. havnt done this stuff since high school. its pretty easy just had a question on that. they need to add an exception to 240.4D that says it doesnt apply to motor and a\c circuits. thats probably a mistake a lot of people make. i would of made the same one if i didnt ask here
 
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