Circuit isolation problem

[nobby61]

I’m currently in the process of replacing the face plates of the sockets in my bedroom. All of the sockets are part of the upstairs ring. The problem that I am having is that when I turn off the MCB for the upstairs ring, one of the spurred sockets remains live but the socket that it is spurred from is dead. The socket remains live until I turn off the Lighting circuit which is on the same side of my split load consumer unit.
I’m wondering if anyone has any idea why this may be happening?

 

[SparkoJon]

Sounds like its spurred from light circuit aswell?

 

[plugwash]

one of the spurred sockets remains live but the socket that it is spurred from is dead.

On what are you basing your assumption about where it is spurred from?

 

[nobby61]

The cables run behind the skirting board. I can see the spur coming from the previous socket, and the cable running to the problem socket

 

[Chri5]

The cables run behind the skirting board. I can see the spur coming from the previous socket, and the cable running to the problem socket

That's not allowed, it doesn't count as a safe zone.

You will need to rerun / replace cables anyway.


What you are suggesting is that the spur has live feeds from both the lighting and ring circuits.

Discon the ring spur wiring you have id and test the socket to see if it 'really' is still live. All lighting circuits are rated at 6 amp, or occasionally at 10 amp.

So consider that if the spur does feed from the light that the potential load would be 26 amp for a double socket, well naughty !

Obviously if the socket has live feeds from both circuits there's something very 'cowboy' going on and I'd suggest you consider getting a pro to PIR the whole system which will give you a comprehensive assessment of everything electrical.

 

[rebuke]

It can't have live feeds from both circuits, if it did then even when you turn off the MCB for your ring main all sockets on the ring would remain live, as there would still be a connection to the lighting circuit through the spur...

 

[Taylortwocities]

What are you doing the testing with??.
If you are using a neon screwdriver or one of the contactless voltage wands then stop as they will lie to you.

You may be getting induced voltages.

Use a proper voltage test instrument or a multimeter.

 

[nobby61]

I'm using a voltage wand. I will get a proper tester and try again.

Thanks for your help everyone

 

[dannyboi2003]

Why dont you just plug a table lamp into the socket, switch it on then isolate the upsatairs ring and see if it goes off or stays on - simples!

 

[TicklyT]

Just wondering if there could be a 'borrowed' neutral feeding the lighting circuit going on there.

That can be very dangerous, as there appears to be no voltage on the neutral until you seperate two conductors. Then one instantly becomes live as you break a circuit you didn't even know was connected to the socket.

You think you've isolated the socket, then as you remove it, the light suddenly goes out. Before you have a chance to think about what to do next, two hundred and thirty odd of the leccy board's best volts, all queued up in an orderly fashion on the end of the neutral lead you've just removed sudenly leap out of the darkness and try climbing up the inside of your left sleeve....