Working in the home electrical installation, the usual light with a pair of two way switches.
Installation seems ok, things does what is expected. However, measuring with the voltmeter, I measure 80V between neutral and the line between switches "passive" (the one that, taken into account the position of the commutators, should not carry power), 230V in the active. Same if I measure from earth cable.
I do not understand why of this 80V voltage.
Worst, even if I isolate completely both sides of the cable, still 40V are measured.
Some explanation about these measures?
circuit is: power line (220V) <=> two way switch 1 <=> two wires <=> two way switch 2 <=> single wire <=> load (lamp) <=> neutral line
Wires between switches are about 5 m long, all wires running together inside a protective corrugate: power, neutral, earth and the two lines between switches.
a) Measuring with the multimeter, 40V-80V appears between one of the wires inter-switches and neutral or earth wire (where I expected near 0V), 230 v in the other one (this is ok).
b) Using as "measure" tool a simple incandescent bulb, no light where the multimeter says 80V.
c) Using as "measure" tool my hand (accidentally and, in fact, the reason I started to measure the state with the multimeter), an small discharge (how much sensitive is the hand?).
d) if I connect a wire between the line with the 80V and the earth wire, the voltage falls to 0V (at least ohm law still working) and security differential device doesn't triggers.
e) If I connect a 40W bulb lamp between the wire with 80V and earth, voltage falls to 0V, bulb made no light. Thanks.