Induced voltage on neutral wire

[Throwgnilli]

Hi everyone,

When checking my consumer unit voltages with the full board off, I stumbled across something head scratching.

Measuring the feed from the DNO, L-N I read 242.3 V. Measuring L-E I measured 242.3 V and N-E I measured a steady 30 mV.

When measuring the live side of the main of the main switch to the dead side of the main switch, I measured 55 V. This as you see in substations is impressed Voltage. At least so I believe.

The head scratching thing I found, is that with each final circuits neutral wire disconnected from the consumer unit (but earth wires connected and live wires connected to the open MCBs (fed from two open RCDs)) I found that each circuits Neutral wire measured 240 V with respect to the DNO Live.

as each of these circuits has appliances in, the only thing I can think of, is that im measuring again an impressed Voltage on the neutral through the cabling and through the appliances, socket ring, light radial etc.

Is this a normal occurance? Anyone come across this before?

 

[James]

If any appliance has a filter or surge protection device, you will have a device that can pass a small current between the L and E or the N and E.
this could give you a true voltage reading as you were getting.