Similar places in two circuits causing trip

[Masham]

I have two line wires coming out of the top of the 'Sockets' B32 MCB. One of those line wires connects to 3 sockets in the bedroom and the other wire connects to 5 sockets in the living room.

Each socket takes two line wires, one to power the socket and the other to pass the current onto the next socket. On the bedroom circuit, the third socket, which is the last in the chain of sockets, has wires that carry the current on, but it is not clear where they go. I will assume it connects back to the consumer unit. If those wires that carry the current on are connected, the 'Sockets' MCB's RCD trips.

The situation is the same on the living room circuit. After the last socket (the fifth on in this case), the wire carrying the current on (again I'm assuming it goes back to the consumer unit) will trip the 'Sockets' MCB's RCD if it is connected.

If the wire carrying the current on is not connected on both circuits, all the sockets are powered.

What do you think could be causing the trip? If both circuits are rings, could the consumer unit be causing the trip?

 

[Octopus]

Sounds like it needs inspecting ................ by a competent spark with a MFT or similar

unplug everything first

 

[Marvo]

Is this arranement recently installed?

 

[TJ Anderson]

What do you think could be causing the trip?

The ring is one circuit with an outgoing and returning wire at MCB.

As RCD is tripping there is either an earth fault on the circuit itself or an item plugged into it.

If I am reading your post correctly it would appear your fault is between the 3rd bedroom socket and the living room socket. They would link to complete ring. That is why it trips when you connect it from either end with the faulty section connected.

 

[Masham]

Thanks for the feedback.

unplug everything first

I made sure I tried it with all appliances removed from each socket.

Is this arranement recently installed?

The installation was done in 2015 when the flat was built.

They would link to complete ring.

That would make sense. It's a shame there wasn't a wiring diagram included when I bought the flat.

 

[telectrix]

if you post your location, one of us should be close enough to assist.

 

[Masham]

Thanks, I have an electrician coming over today.

 

[Octopus]

Thanks, I have an electrician coming over today.

Nice one - thanks for the feedback - and please update us with what his findings are

Being a "ring" circuit - if it was me doing this work, I would be detailing the continuity values, the IR and Zs readings on my invoice.... once finished.

 

[Masham]

As TJ Anderson thought, he found a live earth fault on a wire that connected between two sockets to complete the ring. He found this by removing the three wires that were causing the trip in the two sockets, joined the ends together and tested for continuity. Rather than ripping up the floors to find the wire (thankfully), he made the two ends of the faulty wire safe by cutting off the copper and wrapping tape around them, and reattached the socket to the wall. He's converted the ring circuit into two radials and tested all the sockets.

If he's reading this, many thanks again!