Simple operation " Plug into socket; with the bright, easy-to-see LEDs, verify correct wiring or identify common wiring problems in both standard and RCD outlets Earth fault Neutral fault Live fault Know more, faster "with the handy chart, quickly identify one of six wiring conditions for the outlet RCD outlets"with an integrated RCD test, you can feel secure knowing that your RCD equipped outlets are functioning properly Fast visual identification of all 6 wiring conditions - Correct installation