480VAC motor wiring minimum wire awg with vfd

tom baker

First Chief Moderator
Staff member
Of course, yes. The type of drive does not matter, its based on motor HP.
Part X - Adjustable Speed Drive Systems in Art 430 is a good place to start, in particular 430.122 Conductors Minimum Size and Ampacity

Why would you think there would not be a minimum size?
 
Of course, yes. The type of drive does not matter, its based on motor HP.
Part X - Adjustable Speed Drive Systems in Art 430 is a good place to start, in particular 430.122 Conductors Minimum Size and Ampacity

Why would you think there would not be a minimum size?

Sorry, let me clarify... I know that there is a min. size, but I thought the min. was 14 AWG for a 3-phase 480VAC motor. My application is a 1hp motor with a 1.56 FLA. The motor came in on a piece of equipment with 20awg wire, and I did not think that was correct.
 

paulengr

Senior Member
20 gauge wire is not legal for ANY chapter 1-6 wiring, period. #18 is the smallest. It is legal in communications (chapter 7).
 

Eddie702

Licensed Electrician
Location
Western Massachusetts
Occupation
Electrician
If the 20 gauge wire is factory installed it's not your concern as long as this equipment is listed and approved. If it's not listed and approved that is another matter. #14 is minimum size for motor wiring
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
Thank you - Is #14 min. size for motor wiring in code or more of an industry standard?
14ga is the minimum we can use IN THE FIELD, which is what the NEC is all about. FACTORY built and listed assemblies have their own standards. Under UL508A, INTERNAL Motor Branch Circuits under 5A can use 20ga wire. Field wiring under UL508A is still 14ga though, so it might be a stretch to call the wire from a control panel to a motor "internal". I know my UL inspector would not.
 
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