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?
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