Exception: Separate speed-limiting devices or means shall not be required under either of the following conditions:
(1) Where the inherent characteristics of the machines, the system, or the load and the mechanical connection thereto are such as to safely limit the speed
(2) Where the machine is always under the manual control of a qualified operator
430.90 Combination Fuseholder and Switch as Control ler. The rating of a combination fuseholder and switch usedas a motor controller shall be such that the fuseholder will accommodate the size of the fuse specified in Part III of this article for motor overload protection.
Exception: Where fuses having time delay appropriate for the starting characteristics of the motor are used, fusehold-ers of smaller size than specified in Part III of this article shall be permitted.
VIII. Motor Control Centers
430.92 General. Part VIII covers motor control centers installed for the control of motors, lighting, and power circuits.
430.94 Overcurrent Protection. Motor control centers shall be provided with overcurrent protection in accordance with Parts I, II, and IX of Article 240. The ampere rating or setting of the overcurrent protective device shall not exceed the rating of the common power
bus. This protection shall be provided by (1) an overcurrent protective device located ahead of the motor control center or (2) a main overcurrent protective device located within the motor control center.
430.95 Service Equipment Where used as service equipment, each motor control center shall be provided with a single main disconnecting means to disconnect all ungrounded service conductors.
Exception: A second service disconnect shall be permitted to supply additional equipment.
Where a grounded conductor is provided, the motor control center shall be provided with a main bonding jumper, sized in accordance with 250.28(D), within one of the sections for connecting the grounded conductor, on its supply side, to the motor control center equipment ground bus.
Exception: High-impedance grounded neutral systems shall be permitted to be connected as provided in 250.36.
430.96 Grounding. Multisection motor control centers shall be connected together with an equipment grounding conductor or an equivalent equipment grounding bus sized in accordance with Table
250.122. Equipment grounding conductors shall be connected to this equipment grounding bus or to a grounding termination point provided in a single-section motor control center.
430.97 Busbars and Conductors.
(A) Support and Arrangement. Busbars shall be pro tected from physical damage and be held firmly in place. Other than for required interconnections and control wiring, only those conductors that are intended for termination in a vertical section shall be located in that section.
Exception: Conductors shall be permitted to travel horizontally through vertical sections where such conductors are isolated from the busbars by a barrier.
(B) Phase Arrangement. The phase arrangement on
3-phase horizontal common power and vertical buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the motor control center. The B phase shall be that phase having the higher voltage to ground on 3-phase, 4-wire, delta-connected systems. Other busbar arrangements shall be permitted for