Motor

The National Electric Code (NEC) specifies several ways for motor overcurrent protection compliance. The goal is to protect the branch circuit conductors, the motor controller and the motor against overcurrent and thus overheating due to short circuits or ground faults. The code provides tables for full load current calculations or using the motor nameplate. The code also takes into account the rated service factor when performing the calculation for several motor types including: Single-phase, AC polyphase, inductive squirrel cage, design B, synchronous, wound rotor and DC. The code also specifies ratings or settings for non-time delay fuse, dual element (time-delay) fuse, instantaneous trip breaker and inverse time breakers.

The National Electric Code (NEC) specifies the minimum size for cable tray systems which includes ladder, ventilated trough, ventilated channel, solid bottom and other similar structures. It’s important to note that cable trays are mechanical support systems and not raceways. Raceways are included in another section of the code.

Proper cable tray sizing is complicated and often existing cable trays are overloaded per the code. If you have questions or would like some engineering assistance to properly size your cable tray installation please contact us.