reeseguy
Member
- Location
- Slidell,La USA
First post - want to make sure I get this derating correct.
Have a 3phase 120/208volt service. I have a 3/4" EMT raceway with 6 circuits and 2 neutrals and 1 common ground. Total of 9 - #12thhn wires. (1 neutral per 3 circuits). Using 310-16, #12 thhn rating @30amps, then using 310-15(B)(2)(a) > 30amps x 70% = 21amps. Overcurrent protection would be a 20amp breaker. Is this allowable per the NEC code in this conduit? Do I have to further derate for ambient temperature? If so, exactly how is that done? Which ambient factors am I supposed to use?
Have a 3phase 120/208volt service. I have a 3/4" EMT raceway with 6 circuits and 2 neutrals and 1 common ground. Total of 9 - #12thhn wires. (1 neutral per 3 circuits). Using 310-16, #12 thhn rating @30amps, then using 310-15(B)(2)(a) > 30amps x 70% = 21amps. Overcurrent protection would be a 20amp breaker. Is this allowable per the NEC code in this conduit? Do I have to further derate for ambient temperature? If so, exactly how is that done? Which ambient factors am I supposed to use?