What is the maximum ampacity for over-current devices protecting two or more motors?

When determining the maximum ampacity for over-current devices protecting two or more motors, it is essential to refer to the Canadian Electrical Code (CEC). According to Section 28 of the CEC, when more than one motor is connected to a single over-current device, the device should be rated to not exceed 15 amperes under certain conditions.

This limitation is primarily due to safety considerations. The purpose is to protect the wiring and motors adequately while preventing nuisance tripping that could occur if the amperage exceeds the prescribed limits. By setting the maximum at 15A, the code aims to ensure that the motors remain operational and that the risk of overheating or damage is minimized.

In practical terms, this means that, irrespective of the combined ratings of the motors, the over-current protection device must be appropriately rated to match the 15A maximum unless specifically designed to accommodate more substantial loads and provide proper coordination with the motors.

This alignment with the code supports the understanding that electrical systems must balance operational efficiency and safety standards.