Motor Wire Sizing and the NEC

[noel0589]

Hi all,

I have a question about motor wire sizing. NEC says we gotta follow table 310-16 if we will have motor wire in a raceway. However, it looks like our motor supplier provides leads that are smaller than NEC code would require in a raceway. It looks like they provided leads following table 310-17, for single insulated conductors. My question is two part.
1. What if we do not run the 6 lead wires through a raceway, and instead just bundle them up with a rubber band. Would this count as 6 single insulated conductors?
2. If that is not the case, do we actually have to replace the lead wires that the motor manufacturer provided? Since the motors come from US motors, I would assume that they have certification of their design. Or is their design only good if we keep the wires isolated from each other?

Thanks for any response!

 

[davidbeach]

Wiring within a product is not necessarily the same as wiring outside the product. Use your 310-16 wire in conduit (no, you cannot just rubber band the wires together) and don't concern yourself with the smaller wire in the motor.

 

[jraef]

Correct. The same holds true for control panels and motor starters. Because the final product is subject to testing and (usually) third party approval, the wire sizing rules are different. The higher ratings necessary for field installation, which is what the NEC is all about, are there to cover all of the unknowns that may (or may not) be encountered. Don't fudge on them, it isn't worth it. If you have a fire someday later, an insurance adjuster may negate a claim if they find wiring that was not done to code, even if it had nothing to do with the actual claim!

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[aolalde]

noel0589.
If you see NEC.
Article 310- Conductors for general wiring part 310-1 Scope. This article covers general requirements for conductors and their type designations, insulations, marking, mechanical strength, ampacity ratings, and uses. These requirements do not apply to conductors that form an integral part of equipment, such as motors, motor controllers, and similar equipment, or to conductors specifically provided for elswere in this code..

Then the answer is DO NOT CHANGE THE MOTOR WIRES.

 

[thinker]

Also keep in mind that motor manufacturers typically use special motor lead conductors with the ampacity (and current density) higher than "regular" (building)wires/cables used for field wiring.