According to one aspect, a load control system responsive to electric power from either a first power source or a second power source operable during first and second time periods, respectively, comprises a first circuit responsive to the first and second power sources to develop power waveforms having different characteristics during the first and second time periods. The load control system further includes a second circuit coupled to the first circuit and responsive to the characteristics of the power developed by the first circuit for developing first and second different outputs during the first and second time periods, respectively.