Yesterday I pulled a new wire to an existing breaker in our electric panel. Obvious first step was to turn off the main breaker, which I verified with a non-contact voltage tester (confirmed working before turning off the main breaker, and again after turning the power back on).
While trying to remove the old earth wire from the main panel, my elbow touched a wall and I got shocked.
How is this possible? House was built in 1991, and the main panel is a Nova Line built by Westinghouse. Main breaker is shielded off in its own part, no live wires exposed.