Induced voltage on twin and earth cable

[ThrownRazor25]

Why would I be getting 94v between cpc of twin and earth terminal at DB?

Connected into rcbo with the other end 3 cores separated, nothing connected.

 

[James]

Have you checked insulation resistance?

 

[Lucien Nunes]

Is the RCBO on or off? Are other circuits with nearby cables energised? It's an unusual reading to take, because it doesn't tell you anything very useful. what prompted you to connect the line and neutral but not the earth, and then measure the voltage from that to the bar?

 

[timhoward]

Funnily enough I had something a bit similar today (though lower voltage).

During a CU change there were 3 sets of T+E in a B32 device. I wanted to check it was two for an RFC and one for a Spur and of course check end-to-end readings anyway. I got lucky first time and first two brown wires were showing continuity. As did the blue's and the CPC. I then moved a clip to the 3rd cable to double check and my Metrel tester made the dull sound when it refuses to test, showing 29v L-CPC.

As this was in a cellar, I was a bit naughty and had the board and lighting circuit live while testing other circuits.
When I traced the cable concerned I found it ran very parallel to the live lighting circuit for a long distance, and ended up at a socket with a very long extension lead plugged in. Unplugging the extension lead was enough to make the tester happy and prove what I'd worked out anyway by then, the cable wasn't connected to anything else.