Thanks Karl.
A bit of background. The AC adapter for the camera is the canon one for my camera. As far as I know my camera has a plastic body, which is one of the reasons I've been scratching my head over this. My G11 has metal feet in direct contact with the concrete. I take my leads and powerpacks into work yearly and get them checked, plus I have an earth leakage detector on the switchboard of the house. Also I am generally barefooted when outside imaging.
I did get a surprise one night wearing my cold weather gear (nylon) while wearing ugh boots and sitting on a sheepskin cover when the humidity was around 15% and the wind howling from the SW. I got up to focus my ED80 which had my ATiK 16IC attached and I got belted as I touched the focuser knob. As well as me getting belted the ATiK crashed as did the ToUcam 900 on my guide scope.
Not happy Jan!! So I had a quick lesson on the facts of insulation and grounding. Fortunately both survived but that pesky little white diode in the 900 is only around 1/10 as bright now
