Smaller than 14AWG to fractional HP motors??

[OEMsparky]

At my company, the issue of wire gauge has been bothering me for some time. Our machines range from some that are 120v powered, a few dc drives (fractional HP) to others that are 230 or 480v supplied with VFDs but again all less than 1HP. At issue is the apparent NFPA 79 rule that all motor ("power") circuits be no smaller than 14awg wire. We have some very small motors including one 120v fractional that draws less than 0.25A that come with 20awg leads. It seems ridiculout to run 14awg to these motors - but what is the REQUIREMENT? There are some excpetions in NFPA 79 but all appear to require a (class 10 or 20) overload on motor loads in order to lower the wire size. We're simply feeding 120v through a simple abc type or other basic fuse and then to these small motors. I can't imagine that 14awg is really needed but I haven't found justification to reduce the size. What are the rest of you doing?

 

[stookeyfpe]

You may want to post this in the IEEE portion of the website. It sounds as if you are challenging the NFPA 70 requirements for ampacity of conductors.

I could open up my old college notes on electrical engineering 101 from 20 years ago, the NEC & NFPA 79 and maybe sound like I know something. But I won't. Take the post up to the IEEE page.

I am not being offensive. It is just that NEC issues are generally solved in that forum and the folks up their (just like you) know their electrons.

I'll sit back and learn something.

 

[OEMsparky]

I'm not actually challenging ampacity of conductors - we're talking about whether or not we really need 14awg wire (15amp ampacity) for a motor that draws less than 0.25 amps. That's the extreme but this is what I'm getting at. I'll copy the post to IEEE as well. Thanks.