MCC's and Contollers-Premises Wiring or Utilization Equipment?

[jtinge]

Given the NEC 2014 definition as follows:

Premises Wiring (System). That interior and exterior wiring , including power, lighting, control, and signal circuit wiring together with all their associated hardware, fittings, and wiring devices, both permanently and temporarily installed. This includes (a) wiring from the service point or source of power to the outlet(s), or (b) wiring from and including the power source to the outlets where there is no service point. Such wiring does not include wiring internal to appliances, luminaires, motors, controllers, motor control centers, and similar equipment.

What exactly is meant by the last sentence of this definition?

Ordinarily I would consider an MCC or controller (i.e. VFD) as part of the premises wiring system (as I would a panelboard) since it does not utilize electrical power as would an appliance, luminaire, or motor.

Does this mean an MCC or controller is not considered part of the premises wiring system or just not the factory wiring internal to the MCC or controller?

 

[GoldDigger]

Just the factory wiring internal to it, by the interpretation of just about everybody here.

 

[jtinge]

Just the factory wiring internal to it, by the interpretation of just about everybody here.

I appreciate the feedback.

So to muddy the water a little, is there a gray area where electrical equipment is not utilization equipment, since it doesn't utilize electrical energy, but not necessarily premises wiring either?

I'm thinking along the lines of a large industrial control equipment, covered by NFPA 79 or UL 508.

 

[GoldDigger]

Yes, there are gray areas. Another one of them is what about field installed wiring inside a factory assembly.

 

[Jraef]

Such wiring does not include wiring internal to appliances, luminaires, motors, controllers, motor control centers, and similar equipment.

Not sure where your confusion lies, and why you seem to equate this issue to "utilization equipment". That statement does not use that term in the definition of the exceptions to "Premise Wiring (System)". You have a Service, Equipment, both utilization and distribution, and you have Premise Wiring, which connects the service to either or both of those. Equipment, however defined in sub categories, is tested and listed as an assembly already, subject to other standards and practices that you need not concern yourself with further as far as the NEC is concerned, that's the point of this. But when YOU run your wiring to and from it, THAT becomes the part of the premise wiring system. Service to switchboard, Premise Wiring system; switchboard to panelboard, Premise Wiring, switchboard to MCC, premise wiring. As for MCCs and control panels, up TO the MCC / control panels, and in the case of MCCs all of YOUR wiring run inside of the wire ways to the units themselves, is part of the premise wiring system. But what was wired, tested and listed by the factory as part of the overall assembly is not.

As to devices mounted in the field into MCCs and UL508 listed control panels, that's different. TECHNICALLY, you cannot do that. Notwithstanding the fact that almost everyone does it anyway, the definition does not need to be inclusive of actions that are not permitted.

 

[jtinge]

Not sure where your confusion lies, and why you seem to equate this issue to "utilization equipment". That statement does not use that term in the definition of the exceptions to "Premise Wiring (System)".

Regarding industrial facilities/complexes, I have seen multiple policy docs that use the "premises wiring" and "utilization equipment" as the line of demarcation for identifying when the use of licensed tradesmen is required for installation or modification of electrical systems. My personal opinion is that a more appropriate line of demarcation might be "premises wiring" and "permanently installed utilization equipment" and "cord-connected utilization equipment".