Abstract: The main power service panel is provided with a special sliding gate on the face plate which can be selectively positioned to control the manual throw of adjacent circuit breaker handles for main and auxiliary power inputs fed thereto. The control is such that only one of the two circuit breakers can be conditioned for power transmittal at any one time. Accordingly, primary and auxiliary power supplies can be readily wired to associated main and auxiliary circuit breakers of the main power panel so that distribution circuit breakers of the panel can be energized in the event of failure of one of the power supplies, assuring a supply of power to the discrete distribution circuits. This selected supply to either breaker is accomplished with assurance there will be no back feed of electrical energy to the alternative supply.