NEC wire sizing Q 1

[wzal]

Hi, folks,

I have a question regarding wire sizing per NEC.

UL requires hazardous voltage circuit conductors supplying one motor shall have an ampacity not less than 125% of the motor full load current rating. Does NEC have the same requirement? I found ampacity table 310-16 &17 in NEC 2005 but could not find the similar statement regarding if I need to use 125% factor.

Thanks in advance.

 

[dpc]

NEC requires this for ALL motors. Article 430.22

 

[jraef]

Just so you know also, UL is for building the equipment, NEC is for installing it. So if you already have a UL listed machine and there theoretically was a conflict over the two standards with regards to the internal wiring, the NEC would defer to the fact that the entire machine was already UL listed as an assembly.

 

[wzal]

Thanks for the valuable input. More questions...

Per UL, when the control panel of equipment is designed, do we need to size the wire according to Wiring Ampacity Table AND temperature test the wire, or do just one of the two requirments?

Thanks,