US Patent 10207642 Electrical power monitoring system

An electrical power monitoring system includes a base at an external surface of a wall of a junction box and including a stem configured to project through an opening in the wall, the base further including a monitoring circuit, a plurality of conductors extending through the stem and coupling the monitoring circuit to a plurality of conductive terminals in the junction box, and a fastener configured to mate with the stem of the base at an internal surface of the wall to fix the base to the wall, wherein the monitoring circuit is configured to monitor presence of electrical power at the plurality of conductive terminals, the monitoring circuit including a plurality of light sources at the external surface of the base.