/diy/ - Do It Yourself

>taking a rod of copper, connecting multimeter probe on it
>connecting 2nd multimeteer probe to Ground
>measuring AC Voltage
>Multimeter climbs up to 12V

>Connects the rod to 3rd oscilloscope's probe
>Connects 2nd oscilloscope's probe to a bench PSU, on Building Electricity line (1)
>Connects 2nd oscilloscope's probe to a bench PSU, on Building Electricity line (2)
>Line (1) and (2) are well presenting 2 phases and their shift from the distributing 3-phased cable outside
Rod is measuring a 50Hz signal around 4V amplitude.. not in phase with any of the building's lines.
>Shutting down both power lines of the building, and the rod continue to display same figures
wtf is this leakage. Producing stress in the body. How can I trace it further ?