Have you ever used one of those neon screwdriver voltage testers? I haven’t seen them for a long time but I remember seeing one in a few tool boxes while growing up. I didn’t realize how dangerous they are if the voltage is more than it was designed for! For an interesting experimental test of an insulated screwdriver rated at 1000 V have a look at the 4:45 mark. What is your best guess at what voltage this German made high quality screwdriver will fail at?