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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> S/W Back Box is live - is this normal? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1253628700 Message started by Nigef on Sep 22^nd, 2009, 3:11pm

Title: S/W Back Box is live - is this normal?
Post by Nigef on Sep 22^nd, 2009, 3:11pm

Hi all - can someone please help?

Not in the trade and I am just in the middle of changing a two gang, two way switch for a slim line brass one and noticed with the power on and testing the case with a neon scredriver that the back box is giving a reading (ie, the neon bulb is lit).

Is this by any chance normal? :-? I don't fancy a 240 volt sandwhich before tea!

Many thanks

Nige

Title: Re: S/W Back Box is live - is this normal?
Post by sparky415 on Sep 22^nd, 2009, 5:25pm

Not normal! ;D
The problem might be that you have lost the earth to the switch
and you are now picking up induced voltage with your neon
You could really do with a proper tester!

Title: Re: S/W Back Box is live - is this normal?
Post by CWatters on Sep 23^rd, 2009, 7:46am

The break in the earth may not be at the faceplate. It could be elsewhere leaving a long wire "aerial" connected to the faceplate.

Title: Re: S/W Back Box is live - is this normal?
Post by sparky415 on Sep 23^rd, 2009, 5:36pm

Sorry, that's what I ment by my post

Thanks CW, :)

I might be wrong and there might be 230v on the new brass switch.....
Nigef might be in heap on the floor....
Nige come back and tell us what you found please....
I might not be able to sleep if you don't ::)

Title: Re: S/W Back Box is live - is this normal?
Post by Nigef on Sep 26^th, 2009, 8:24am

Thanks for your help and concern guys.

It looks like the Sparky who had wired up the thing 15 years ago must have sliced the live accidentally and I must have then pulled the earth accross it when fitting the new S/W. A bit of insulting tape and I managed to have tea and scones later that day as normal and not looking like a burnt sausage :-[

Title: Re: S/W Back Box is live - is this normal?
Post by CWatters on Sep 26^th, 2009, 9:59am

Why didn't that fault blow the fuse or trip the RCD?

Title: Re: S/W Back Box is live - is this normal?
Post by sparky415 on Sep 26^th, 2009, 4:23pm

As CW says if you didn't blow a fuse or trip a RCD there's something wrong with your wiring

Also was there any green sleeving on the earth wire? :-/