An input line selector system provided to selectively connect one of two input power lines is configured with a single switch provided in series with each of the input power lines, the connection between the switches being made such that it prevents reverse flow of current in the event that the switches are OFF. A smart, simple and precisely operating automatic line selector is provided to control the operation of the two switches. The line selector system configuration is simple and implements only two switches and can be applied to a linear charger or switching charger application with addition of one or two switches respectively, thereby providing a simple, efficient and cost effective system.