Figure 7-5.Motor controllers basic rules and exceptions.
motors of the group should be permitted to serve the group of motors under any one of the following conditions:
Where a number of motors drive several parts of a single machine or a piece of apparatus, such as metalworking and woodworking machines, cranes, hoists, and similar apparatus.
Where a group of motors is under the protection of one overcurrent device, as permitted in NEC ® section 430-53(a).
Where a group of motors is located in a single room within sight of the controller location. A distance of more than 50 feet (15.3 meters) is considered equivalent to being out of sight.
Each motor, along with its controller or magnetic starter, must have some form of approved manual disconnecting means, rated in horsepower, or a circuit breaker. This disconnecting means, when in the OPEN position, must disconnect both the controller and the motor from all ungrounded supply conductors. It must plainly indicate whether it is in the OPEN or the CLOSED position and may be in the same housing as the controller.Continue Reading