A retrofit 60 Hz current sensor for non-intrusive power monitoring at the circuit breaker

We present a new sensor for power monitoring that measures current flow in a circuit breaker without permanent modification of the breaker panel or the circuit breaker itself. The sensor consists of three parts: an inductive pickup for sensing current from the breaker face, an inductive link designed to transmit power through the steel breaker panel door, and a passive, balanced JFET modulator circuit for transmitting information through the inductive link. The demodulated breaker current signal is available outside of the breaker panel door. This sensor provides a solution for low-cost, non-intrusive retrofit of any circuit breaker panel for centralized power monitoring.