derating

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if i have 6 number 12 thhn/thwn wires in a 3/4 inch emt conduit, am i o.k before i have to derate based on more than three current carrying conductors in a conduit you apply an adjustment factor 4-6 conductors 80%,7-9 conductors 70% table 310.16 has #12 at 75 deg is rated for 25amps,
so 25amps*80%=20amps will six be o.k in the 3/4 emt conduit before i have to go to the next size wire up.
 

infinity

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THHN is a 90 degree C conductor so you could use the 90 degree C ampacity from table 310.16 not the 75 degree C ampacity. You could use up to 9 CCC's without having any affect on the 20 amp ampacity of #12 THHN.
 

SEO

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Location
Michigan
For a thhn conductor you can use 90 c when applying the adjustment factors . Table 310.16 #12 thhn is 30 amps X 80 percent is 24 amps . Looks like your good to go. Also see 240.4(D).
 
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