Abstract: An electromechanically controlled switch assembly including an automatic, three position, removable, transfer switch and a three position, manually operated bypass switch assembly. Electromechanical controls are utilized to sense the position of both switches, including whether or not the bypass switch is being manually switched to the normal or an emergency source of power, whether or not the power sources are available, and whether or not the transfer switch is properly located within its supporting frame for normal operation, completely isolated, or isolated from the load but in the correct location for testing.