An isolating switch with visible break contacts shall be installed on the ______ of the disconnecting means.

The correct placement of an isolating switch with visible break contacts on the supply side of the disconnecting means is crucial for ensuring safety and compliance with electrical standards. By installing the isolating switch on the supply side, any maintenance or servicing work can be performed safely, as it ensures that the electrical supply to the equipment or circuit can be completely isolated.

This installation prevents the inadvertent energization of the circuit, protecting personnel from electrical shock or injury while working on equipment downstream. The visible break feature allows workers to confirm the switch is open and the circuit is de-energized before beginning any work, adding an additional layer of safety by providing a visual indication of disconnection.

Placement on other sides—like the return, ground, or neutral—would not meet the safety requirements for isolation, as they do not effectively cut off the power supply to the circuit. Thus, positioning the isolating switch on the supply side aligns with best practices in electrical safety standards.