As I indicated in part two of this series, there were many changes to Article 100. The relocation of definitions from other articles into Article 100 resulted in the addition of new definitions, changes to some existing ones and deletion of several others. There were also some changes to harmonize definitions between panels. Branch Circuit, Motor. This new definition was added to recognize the difference between a branch circuit, which is defined as "the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s)," and a motor branch circuit, which can include controllers, starters and variable-frequency drives. The controller can be as simple as a snap switch or a complex drive that includes protective devices against overload, short-circuit and ground-fault. Class 4 Definitions. Seven new definitions were added that work hand-in-hand with new Article 726, Class 4 Power Systems. The new definitions include Class 4 Circuit, Class 4 Device, Class 4 Power System, Class 4 Receiver, Class 4 Transmitter, Class 4 Tray Cable (CL4TC) and Class 4 Utilization Equipment. Class 4 power systems rely on transmitters that deliver power to a Class 4 receiver, often referred to as a powered device. Class 4 transmitters establish an electronic handshake with the Class 4 receiver and actively monitor the electronic handshaker to verify that the powered device is present and operating properly. An informational note was added to the definition of Class 4 transmitter noting that they differ from traditional sources in that they monitor for faults, including line-to-line and line-to-ground faults.
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