A conductor configuration and a power flow of an electric power transmission line set is determined at a location along the line set, and positions in a substantially planar area that is transverse to the line set are determined where a predetermined change in the power flow results in a maximum change in the magnetic field at the positions. A system for monitoring power flow includes a plurality of magnetic field monitors placed at the selected positions, and a central processing facility for communicating the power flow to an end user. A method for monitoring power flow includes selecting positions for placement of a plurality of magnetic field monitors, placing the monitors, determining a power flow, and communicating the power flow to an end user.