Some lights not working. Strange voltage readings !

[Richard Snell]

Hello all,

We have a strange problem with our electrics. Our main living room light does not work or the wall lights in the same room. Same thing in the master bedroom and one of the lights in the hall. All other lights in the house are fine.

I invited a friend over who knows something of electrics and he checked the fuses and took voltage readings at the light fixture and the at switches.

He found that there was no voltage at the switch ( about 3V ) but managed to get a reading of 246V at the light fixture in the lving room. He got about 150V in the hall !!!

We both thought you should either get 0V or 240V !!

Does anybody know what could cause these strange readings or have had similar problems in their house ?

Cheers

[Geo]

Probably a digital multimeter... Try an AVO 8

Geo

[Ian Stirling]

Digital meters can often measure the small capacitive currents induced by wires lying next to each other. This is not a 'real' voltage, if there is any load, it will fall to zero.

[Andrew Gabriel]

The strange readings are caused by a high input impedance meter, and capacitive coupling of disconnected conductors to nearby live conductors.

[Tim Mitchell]

Also the mains voltage is "nominally" 240V but I've seen it as low as

200V and as high as 265V.

If he found no voltage at the switch, sounds like he was measuring across the switch? To get anything meaningful, one meter probe has to go to earth or neutral, the other probe to the voltage being measured.

[Pete C]

Hi,

A test lamp should tell you if the wire is genuinely live or not, needs connecting to a working neutral though.

cheers, Pete.