National Power Industries manufacture and dealers of ab switche, goab switche, disconnecting switche, single phase switch change over switch. switches for higher line current breaking capacity for line Isolators. Earth switch can be easily installed on each pole at either end and interlocked mechanically the main switch. the auxiliary switches can be provided for man as well as for earth switch. Electrical interlock can be provided, Electrical motor drive mechanism complete with reduction gear and torque limiting safety features can also be provided, Air Break Switch Disconnectors are part of any overhead line network, providing crucial points of isolation.