12v on socket ring main after isolation.

[Taylor_J]

Hello all!

I've come across a bit of a problem today as I was changing a socket and got a tingle (Isolated the MCB of course).

I tested the voltage and it was pulling 12v.

I've found when you isolate the upstairs lights the 12v on the upstairs sockets disappears.

Its a 17th edition dual RCD split load board.

The upstairs socket ring is on the first RCD and the upstairs lighting circuit is on the second RCD.

Any one got any answers for this problem or has anyone come across this before?

Thank you

 

[telectrix]

think it's a question of dissing each circuit from CU and testing between circuits to see if there's some sort of inter connection, possibly coupled with a poor connection on one of the circuits.

 

[Taylor_J]

I think that will be the case. Its strange as if they were connected surely the RCD would trip as its on the other side?

 

[Deleted member 9648]

Could be just induced voltage....although you wouldnt expect a tingle from that. Only answer is a testing session at the DB

 

[richy3333]

What's a socket ring main eh?

 

[Taylor_J]

What's a socket ring main eh?

Believe it or not I have come across a lighting ring main before

 

[Octopus]

Got to be induced voltage.

 

[SPARTYKUS]

Try it with an analogue meter ;-)

 

[jeremy]

A tingle from 12V? you need tougher hands!

 

[jeremy]

That probably isn't very helpful to you! My guess would be induced voltage. I wouldn't have thought there'd be any real energy behind it. Do you understand about induced voltage? Not trying to show you up, but it can seem a bit unbelievable.

 

[Taylor_J]

That probably isn't very helpful to you! My guess would be induced voltage. I wouldn't have thought there'd be any real energy behind it. Do you understand about induced voltage? Not trying to show you up, but it can seem a bit unbelievable.

Haha no worries. Electromagnetic I take it? To be fair mate I have never come across this before in 10 years of house bashing. It just threw me a bit. The loop impedance, insulation resistance, rcd and r1+r2s all came out fine.

 

[telectrix]

as said, it could be an induced or phantom voltage and the tingle could have been static.

 

[UKMeterman]

See if the 12V is still there measured with an Avo 8

 

[PEG]

Could be just induced voltage....although you wouldnt expect a tingle from that. Only answer is a testing session at the DB

You can receive more than a tingle,from an induced voltage,depending on the circuits doing the inducing,and the ones being induced. Any equipment connected to other circuits,MAY have the capability to "hold" some of that inducement.
If you imagine how a transformer functions,with both sides separated via insulation,it is not hard to imagine the generating of substantial voltage,as conductors wind their way around each other,especially when bunched.
Try it out,with two lengths of T&E,and a horse-shoe :icon12: