Suitable for isolation with positive contact indication

Suitability for isolation is defined here by the mechanical reliability of the position indicator of the operating mechanism, where:

• the isolation position corresponds to the O (OFF) position

• the operating handle cannot indicate the "OFF" position unless the contacts are effectively open.

The other conditions for isolation must all be fulfilled:

• locking in the open position is possible only if the contacts are effectively open

• leakage currents are below the standardised limits

• overvoltage impulse withstand between upstream and downstream connections.