> I hooked the ground crocodile clamp of my scope to what I thought was the ground but which in fact was V- of the DC supply voltage of the neon light installat

> I hooked the ground crocodile clamp of my scope to what I thought was the ground but which in fact was V- of the DC supply voltage of the neon light installation that was use to drive the display. Yeao! I own a couple of high-voltage differential probes for this very purpose. Even though most single-ended scope probes are rated to 300V Cat II, I won't go anywhere near main's power with them.