Motor Replacement P-Lead Question

[mckaype]

In a Class 1 Div 2 location a motor (say 2 hp or greater) has failed and must be replaced. Options are: 1) Have a UL Motor shop rebuild the old motor. (Added benefit - we can re-install it easily since the flex and fittings already fit.) 2) Install a replacement motor. My question is about option # 2. Suppose the new replacement motor comes with P-Leads (thermal elements that will open a control circuit if the motor gets too hot). The original installation is old. The original motor has no P-Leads. There is no P-Lead control circuit at the motor. If we install the new motor with P-Leads - Does the NEC required us to utilize them? This would require bringing a control circuit from the MCC to the motor location. Our old motor was/is thermally protected in the MCC with OL elements. Thanks!

 

[rbalex]

Have you been using explosionproof motors in this application?

 

[mckaype]

Have you been using explosionproof motors in this application?

Yes. Class 1 Div 2 TEFC Motors

 

[rbalex]

UL listed TEFC explosionproof motors are designed for Division 1. Although explosionproof motors can certainly be used in Division 2, they don't have to be. In fact, almost any three-phase motor is acceptable in Division 2.

Except in very limited applications, UL does not list motors for Division 2. CSA lists them but the listing is meaningless in US domestic applications.

That said, if the motor is UL listed and comes with an internal thermal switch it must be included in the control circuit per any manufacturer instructions.

 

[mckaype]

UL listed TEFC explosionproof motors are designed for Division 1. Although explosionproof motors can certainly be used in Division 2, they don't have to be. In fact, almost any three-phase motor is acceptable in Division 2. Except in very limited applications, UL does not list motors for Division 2. CSA lists them but the listing is meaningless in US domestic applications. That said, if the motor is UL listed and comes with an internal thermal switch it must be included in the control circuit per any manufacturer instructions.

Thanks Bob - So it's a listing and labeling issue (use as the mfg specifies) rather than a NEC Code requirement? Can we generalize the rule to say that when replacing motors in classified locations - if the replacement motor has P-Leads (thermals) then they must be used?

 

[rbalex]

Thanks Bob - So it's a listing and labeling issue (use as the mfg specifies) rather than a NEC Code requirement? Can we generalize the rule to say that when replacing motors in classified locations - if the replacement motor has P-Leads (thermals) then they must be used?

It's an NEC issue through 110.3(B). Can't quite make a general statement; it's possible the manufacturer won't require them in Division 2. But remember, almost any three-phase, TEFC motor is acceptable in Division 2.