What is the recommended accepted standard for branch circuit protection of electric motors?

The recommended accepted standard for branch circuit protection of electric motors is to use fuses or circuit breakers. This is because these devices are designed to protect against overcurrent conditions, which can occur due to overload or short-circuit situations. Fuses provide a one-time protection mechanism that physically melts in response to excessive current, while circuit breakers can be reset after tripping, allowing for a more convenient solution for repeated use.

Electric motors are subject to varying conditions where the current draw can exceed normal operational levels. It is essential for the protection devices to trip quickly to prevent damage to the motor windings or other components. Fuses and circuit breakers also ensure that the entire circuit is adequately protected, maintaining safety and reliability in electrical systems.

While overload relays specifically protect against overheating in motors due to prolonged overload conditions, they are not the only requirement for overall circuit protection. Manual switches and ground fault interrupters serve different purposes and are inadequate as standalone solutions for branch circuit protection of electric motors. Thus, using fuses or circuit breakers aligns with the best practices and standards in electrical safety and protection.