Why Testing Grid Switches Can Be a Nightmare for Electricians 1 Way Lighting Circuit Wired in Conduit - Continuity of the CPC & Insulation Resistance Tests In this video we look at carrying out the dead tests on our 1 way lighting circuit wired in PVC singles in a plastic conduit exercise. I demonstrate how to set up my Megger MFT tester and then carryout the continuity of CPC test and include the polarity test at the same time. Next I go on to demonstrate how to carryout the insulation resistan