Extech RT30 Wireless AC Circuit Identifier with External Probe Simplify mid-run wiring jobs by easily identifying the correct circuit powering the cable to be splices or repaired Combines non-contact voltage detection with wireless signals to monitor and remotely report the presence of voltage on a wire Eliminates the need for an assistant or back-and-forth trips to confirm the correct circuit is powered down Clamp-style probe accessory is ideal for wires that are hard to isolate or reach Also identify lighting or outlet circuits with the built-in light sensor