What should you do first when isolating an electric motor driven pump?

When isolating an electric motor driven pump, the first action should be to open the motor breaker. This step is crucial because it cuts off electrical power to the motor, ensuring that the pump cannot be accidentally started during maintenance or isolation. By disabling the electrical supply, you eliminate the risk of electrical shock or accidental operation, which could pose safety hazards to personnel working on or near the pump.

Following this initial step, other isolation procedures, such as closing valves or draining the system, can be performed safely, but ensuring the power is off is the fundamental priority. This approach promotes a safe working environment and conforms to standard safety practices in managing electrical and mechanical equipment.