Definition of what is a motor.

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Piethief

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Hello All,

I am a new electrical designer in the MEP space, and I am looking for feedback on when people classify a load type as "motor". Within the NEC I do not see a formal definition. For example, I've worked with the following equipment.

Centrifuges - Usually 208V single phase that plug into an outlet.
Laboratory hood - Usually contains a DC motor along with a couple of general purpose outlets to a single point connection.
Hepa filter motors - recently it was 1A 277V input but contained a DC motor.
Kitchen Aid stand mixers - 120V.

I've worked with people who would classify all of these load types "Receptacle" according to NEC reduction allowances (I know thats not allowed, but thats another conversation).

My gut feeling is, if there is any kind of motor, then the whole thing is a motor, so all 4 examples I've listed would be motors to me. It should be given the full attention of MCA and MOCP requirements and motor load calculations.

Thank you for your time and feedback.
 
don_resqcapt19 said:
In my opinion those items would be under Article 422, Appliances, and not Article 430, Motors.
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Hi Don, thanks for the reply.

In 422.1 scope, my NEC (2017) has details in blue that states "Article 422 covers appliances that may be fastened in place or cord and connected, such as air-conditioning units, dishwashers, heater appliances, water heaters..." So it includes air conditioners that are plug in.

For appliances, 422.3 states "Article 430 shall apply to the installation of motor-operated appliances..." also "...Article 440 shall apply to the installation of appliances containing a hermetic refrigerant motor compressors...".

Based on that, I think those types of items I listed should still fall under article 430.

Any other thoughts on that?
 
gadfly56 said:
Depending on the size of the hood (CFM), it might be more properly classified as a traditional motor.
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That's an interesting take on classifying motors. Do you have literature for something like that?

I understand that at a small scale, classifying a 100W fan as a motor vs non continuous load wouldn't be significant on a building that has, say a 3MW service. But at what point should begin to make that distinction?
 
Piethief said:
Hi Don, thanks for the reply.

In 422.1 scope, my NEC (2017) has details in blue that states "Article 422 covers appliances that may be fastened in place or cord and connected, such as air-conditioning units, dishwashers, heater appliances, water heaters..." So it includes air conditioners that are plug in.

For appliances, 422.3 states "Article 430 shall apply to the installation of motor-operated appliances..." also "...Article 440 shall apply to the installation of appliances containing a hermetic refrigerant motor compressors...".

Based on that, I think those types of items I listed should still fall under article 430.

Any other thoughts on that?
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Is the info in blue from the handbook, if so thats just commentary, not always correct, and may not be enforceable.
A motor is a motor and nothing more. If the motor is in a washing machine, then its part of that.
I am not sure what MEP is or does, but if you are making something, then it would be up to your listing organization,( UL, et al) to determine what it is and then that determines what article in the NEC it belongs in.
Remember the NEC is an installation standard.
 
Piethief said:
That's an interesting take on classifying motors. Do you have literature for something like that?

I understand that at a small scale, classifying a 100W fan as a motor vs non continuous load wouldn't be significant on a building that has, say a 3MW service. But at what point should begin to make that distinction?
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To answer your question directly, I don't have and am not aware of any rule of thumb on motor classification, but I'm not a motor guy. So, a large laboratory hood, or several together served by a single exhaust fan might easily be 2 HP or so. That's a real motor, isn't it?
 
tom baker said:
Is the info in blue from the handbook, if so thats just commentary, not always correct, and may not be enforceable.
A motor is a motor and nothing more. If the motor is in a washing machine, then its part of that.
I am not sure what MEP is or does, but if you are making something, then it would be up to your listing organization,( UL, et al) to determine what it is and then that determines what article in the NEC it belongs in.
Remember the NEC is an installation standard.
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"Mechanical Electrical Plumbing", usually an engineering firm offering those design services. On a large project the architect is often the prime designer and then hires one or more MEP firms to fill in the details for mechanical systems. Some firms may be highly specialized, like an acoustical consultant hired for a opera house or theater build, or geotech services for soil strength, etc. It may just be my peculiar experience, but structural firms don't seem to do anything else except structural.
 
Piethief said:
Hi Don, thanks for the reply.

In 422.1 scope, my NEC (2017) has details in blue that states "Article 422 covers appliances that may be fastened in place or cord and connected, such as air-conditioning units, dishwashers, heater appliances, water heaters..." So it includes air conditioners that are plug in.

For appliances, 422.3 states "Article 430 shall apply to the installation of motor-operated appliances..." also "...Article 440 shall apply to the installation of appliances containing a hermetic refrigerant motor compressors...".

Based on that, I think those types of items I listed should still fall under article 430.

Any other thoughts on that?
Click to expand...
It falls to 422.10(A). If the equipment has a nameplate with the load information, you use that. If it doesn't you use the rules in 430 and the motor horsepower.
 
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