Abstract: An energy conserving transformer power supply system comprising one main transformer of large capacity to carry the maximum load under normal occupancy hours and one auxiliary transformer of relatively very small capacity to carry the utmost minimum load under non-occupancy hours (nights & week-end) being supplied from the same load distribution center. A transfer switching means is provided to alternately transfer the power supply from main to auxiliary transformer or vice-versa in response to the control action of a program timer switching means in accordance with the timing schedule of the occupancy and non-occupancy hours.Additional current sensing means is provided to override the program timer switching action should the demand load exceed a predetermined low level and to restore the main control action on the program timer after cessation of such temporary condition.