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Got a weird situation in my house. Sorry for the horrible "hand drawing" below and also for probably not using the correct terms (i'm not an electrician).

Here's one of the multiple circuits in my house: there's a circuit breaker (just a regular one that breaks on overcurrent, not the differential kind), then wires leaving through a long (5-10 meters), flexible PVC tube to another part of the house, through a wall socket and to an appliance (washing machine, let's say).

The question is: if the PE (protective earth) conductor - yellow in my drawing - is disconnected from the ground (?) at the distribution board, how normal is it to see a voltage between the points marked "Voltage here?" in the drawing (when there's also voltage on the live wire)? I've got multiple such circuits in my house and, for some, if you touch the disconnected PE conductor, you can feel a pinch in your fingers. Contact voltage detector also lights up slightly, and using a multimeter can show even ~60V in high impedance mode, or a much lower value in low impedance.

So, could this be ghost voltage (and therefore not a more serious problem)?

Otherwise, this could indicate a defective appliance (what if this phenomenon occurs with the appliance plugged in and disappears without?) ? Or an insulation fault between the line, neutral and PE conductors (this happened a few times before, because of probably broken conductor insulation and moisture in the PVC tube - from when the house was built)?

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  • Just how much voltage are you getting with your voltmeter in the low-impedance mode? – ThreePhaseEel Sep 4 '19 at 11:35
  • A few volts, say 1-3V – Unknown Sep 5 '19 at 12:42
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As I've said elsewhere, phantom voltage shouldn't bite.

Yes, the Protective Earth wire will will pick up (via induction or capacitance, like a radio transmission) a very tiny amount of energy from the adjacent hot wire. However, that should only register on a very sensitive meter, such as a DVM.

A low impedance meter should instantly exhaust the voltage, leaving no readable figure.

Alternately, you can put an ammeter across the connection and see how many amps want to flow. If it's more than microamps, it isn't phantom voltage - and if it's more than 5 milliamps, it is a life safety threat, and at least in America, a GFCI (RCBO) would trip.

Given that your low-impedance meter still sees the voltage, and it throws a visible spark, this is genuine residual current leakage, and it needs to be dealt with. You're lucky to catch this one; often, ground faults go through fourth routes that you wouldn't see on the earth wire.

Now you should begin removing appliances until the leak goes away. That will be the faulty appliance, and it's time to fix or replace it.

It might happen due to faulty wiring, but that generally happens when someone uses interior wiring in an outdoor location. This does not sound like an outdoor location.

  • Just replaced the wiring in such a circuit: the appliance wasn't plugged in, only the live wire connected to the distribution panel. We were seeing ~40V between the neutral/ground wire and the ground at the distribution panel with a multimeter in high impedance mode; in low impedance mode it was close to 1-2V (I'm a bit puzzled, they say a low impedance multimeter should show 0 for ghost voltages, but I'm actually picking up a few volts, and since the wiring had been replaced, it must be ghost voltage - it also tingles when you touch the wire). Nice idea with the ammeter, will try next time. – Unknown Sep 5 '19 at 12:51
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With the wire disconnected you leave an antenna or kind of like that. When wires are routed in close proximity the electrical field from the energized wires inductive couples some voltage on the disconnected conductor. This is how transformers work, the more wire in close proximity will provide higher currents. Ghost or phantom voltages have no real potential or current but the voltage is there that’s why we call it ghost or phantom voltage even a slight load it disappears.

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