These specifications are intended as a reference for purchasers and users of circuit breakers in the preparation of requests for quotations and as a reference for manufacturers and vendors in submitting bids. 12-1.2 These specifications apply to all types of alternating- current power circuit breakers (indoor and outdoor) having an interrupting rating of 50 mva or higher and a voltage rating above 1500 volts. Individual clauses apply to all types except where otherrewise indicated. 12-1.3 These requirements of necessity include some elements of construction and materials, but are not intended to preclude ingenuity of design or improvement.