Electrical question - strange lightswitch behaviour?

[Adam-the-Kiwi]

Hi all,

We've just replaced the ceiling in our kitchen/diner while doing other work. As a result of this, I've removed three lights and replaced two plastic pendant fittings with 4-pole junction boxes screwed to the joists.

Once this was done, but before the light fittings were replaced, I noticed that my voltage meter was reading ~50V with the switches off. When I investigated the switch (a three-switch unit) I found that the voltage across the terminals was ~190V.

Any ideas what could be causing this? Is it a major concern? All the lights on this circuit seem to work without problem...

Cheers - Adam...

[John Williamson]

As a result of this, I've removed three lights and replaced two plastic pendant fittings with 4-pole junction boxes screwed to the joists.

that my voltage meter was reading ~50V with the switches off. When I investigated the switch (a three-switch unit) I found that the voltage across the terminals was ~190V.

this circuit seem to work without problem...

Depending on your meter, a few microamps of leakage through the switch insulation or through minute amounts of condensation or humidity in the switches or junction box could give you those readings. Also, if your meter has a very high impedance, the readings could possibly be explained by capacitive effects within the cables.

You should find that with the light fittings and even very low power lamps in place, you get the expected zero voltage across the fittings and 240V across the switches.

[Roger Mills]

As a result of this, I've removed three lights and replaced two plastic pendant fittings with 4-pole junction boxes screwed to the joists.

that my voltage meter was reading ~50V with the switches off. When I investigated the switch (a three-switch unit) I found that the voltage across the terminals was ~190V.

this circuit seem to work without problem...

Probably induction from wires running parallel with other wires. And you are probably using a very impedance voltmeter. If you use a conventional 'mechanical' voltmeter which draws a bit more current, the voltages will probably disappear.

[The Natural Philosopher]

As a result of this, I've removed three lights and replaced two plastic pendant fittings with 4-pole junction boxes screwed to the joists.

that my voltage meter was reading ~50V with the switches off. When I investigated the switch (a three-switch unit) I found that the voltage across the terminals was ~190V.

this circuit seem to work without problem...

capacitive coupling + a very high impedance digital voltmeter.

One reason I dislike DVMs.

[Harry Bloomfield]

harry pretended :

I could say the same about some 'electrical engineers'.

[The Natural Philosopher]

You could, but you would (as usual) be wrong.

[dennis]

8<

Nice to see you know all "electrical engineers". How did you test them all?