Which statement about the isolating switch for electric pumps is correct?

• A. It should be open
• B. It should be closed
• C. It should be left in the opposite state to the pump status
• D. It should be toggled periodically

Answer: (B)

The essential idea is that the isolating switch is a protective disconnect that must allow the pump to receive power when it’s supposed to run. Keeping it in the closed position ensures the pump remains connected to the electrical supply so that, when the control system calls for operation, the pump can start immediately. If the switch were open, the circuit would be broken and the pump could not start, defeating readiness for operation in an emergency or during testing. The option that the switch should be left opposite to the pump status would introduce confusion and delay, since the pump and supply would never align for proper operation. Periodically toggling it isn’t a safe or practical practice during normal operation or testing.