I have been tinkering as an enthusiastic hobbyist in my garage 'lab' for about a year. It's an old rented house in Sydney, Australia. Puzzled by several odd small shocks and confusion as to why my oscilloscope insists that my current project's circuit ground is somewhere around +2.4VDC, I thought to put a voltmeter across the garage floor slab and the wall outlet's earth/ground terminal.
According to my DVM there is 50Hz AC present between the floor surface and 'earth' measuring over 100VAC.
Mains AC here is 240V, 50Hz.
Similarly between the floor and the project on my wooden bench which is not connected to any appliance the DVM shows 40VAC.
Voltages measured between the floor and other metal items within reach (old Tektronix scopes) are in the region of 15 to 30VAC.
The floor is reinforced concrete direct on the ground and gets damp when it rains (as was the case when I made these measurements).
I plan to tabulate voltage measurements to see if these change (with weather, say), but this suggests to me that the house's earth wiring might be wholly fictitious!
Sanity check, please - I'm enthusiastic but not experienced and I don't mess with mains power. I'd like to understand what's happening though!