My drywall guy complained of several electrical shocks while putting drywall mud around a window. No shocks while installing the corner bead though. I test it with a pen type tester, and the metal glows hot. I get no shock, no matter how long I touch it. When I put my finger on the metal, the pen tester light goes out, as I am likely a good ground. The metal is not touching any wires, although there are wires about a foot below the window, and one a little to the side. I turned off the breaker to that area, and the pen light goes off. How could there be electricity in a window bead that isn't touching wires? Any help here would be great. I'd hate to have to take the siding off the house to find a possible nail penetrations etc. if this isn't the problem.