A journeyperson is installing a new submersible pump in a well. The pump motor nameplate indicates a full-load current of 12 A at 240 V. The circuit protection will be a circuit breaker. What is the MAXIMUM standard rating for the circuit breaker permitted by the Canadian Electrical Code (CEC) for motor branch circuits lacking specific overload protection in the breaker itself?

Question: A journeyperson is installing a new submersible pump in a well. The pump motor nameplate indicates a full-load current of 12 A at 240 V. The circuit protection will be a circuit breaker. What is the MAXIMUM standard rating for the circuit breaker permitted by the Canadian Electrical Code (CEC) for motor branch circuits lacking specific overload protection in the breaker itself?

Answer options:

• 15 A
• 20 A ✅ 25 A
• 30 A

Correct answer: 25 A

Explanation: Rule 28-200(a) and Table 29 of the CEC allow for circuit breakers that do not have adjustable trips to be sized at 250% of the motor full-load current for a single-phase AC squirrel cage motor. 12 A x 250% = 30 A. However, Rule 28-202(1)(d) states that where the rating of the branch circuit overcurrent device is greater than 20 A, it must not exceed the maximum rating of supplementary overcurrent protection marked on the pump motor or controller. If not marked, a 25 A breaker is the next standard size down if 30 A exceeds other limitations, and 25 A is commonly used for a 12 A motor. For a 12A motor, a 25A breaker is the common and code-compliant choice by following the next standard size down from the calculated 30A.