<p>A unit frame (5) carries breakers and relays, etc. and can be moved onto or from a shelf in a main frame (1). A contractor frame (9) carries power supply contactors (7) and a load contactor (8) for contacting busbars (10) and a load contact (11). The frame (9) can be moved relative to the unit frame in contact make and break directions. A lever linkage (16) converts movement of a control handle (18) at the front of the unit frame to contactor frame movement in contact make or break directions and includes control elements for moving contactors to connection, circuit breaking or other positions.</p>
