How must the service disconnecting means indicate its operational position?

The service disconnecting means must clearly indicate its operational position by providing a plain indication of whether it is in the "on" or "off" state. This requirement is crucial for ensuring the safety of individuals working on electrical systems, as it allows them to quickly ascertain whether the circuit is energized or de-energized. A straightforward indication, typically through a label or a visible marker, helps prevent accidental energization while maintenance or service work is performed.

While other methods of indication like lights or sounds could potentially serve as indicators, they may not always be as direct or clear as a simple "on" or "off" labeling. Mechanical locks can secure the disconnecting means but do not necessarily communicate its operational status. Therefore, clarity in indicating whether the service is active or inactive is essential for safe operation and compliance with the National Electrical Code.