Re-routing a ring mains

[Jupiter01]

No,if there is a problem it would be open circuit, but the point of the test, will confirm your thoughts and prove you are actually going to bypass the correct faulty section.

Sounds like the Eicr may have failed on End to End, L to L as well as E to E continuity, though does not prove the Broken Live is necessarily in the same section of cable as the broken Earth.

I agree that the EICR doesn’t state that the break for L and E is on the same cable section. It just says that there is a break somewhere on that circuit.

Doesn’t the troubleshooting steps I have set out prove that both breaks are actually on the same section of cable?

 

[333rocky333]

Yes it does, just saying a second opinion, quick test to confirm is never a bad idea, technically you have done the same thing using a wander lead as opposed to the Existing unbroken N wire.
It just seems odd for a L and E to go open circuit in the same place without other issues like tripping occurring.

 

[Jupiter01]

Hi All,

I embarked on these changes earlier in the week and have come away with more questions than I started with...
None of my previous testing made any sense and I spent half the day testing again. I was hoping to do a quick verification of the previously identified faults and then move straight to making the necessary changes. Felt like I was in a different house! I am desperately trying to recall the confusion I faced as I wanted to make sense of it all afterwards. I am hoping you can solve a few puzzles for me. Here’s my recollection of events.

• Started by locking off the MCB for the affected ring
• Ran around with socket tester and all went to plan. This identified the sockets on this ring.
• Removed a random socket (landing) on the ring. Different to the one I removed previously
• I grabbed the ends of live and live - continuity was good. Same on neutral and no continuity on earth. Again, as noted in EICR
• I then went to the socket upstairs (bedroom) where I was convinced the earth break was (between here and the living room). Unscrewed the bedroom socket and had the cables hanging in the air. I wanted to double check that this is definitely and directly connected to the living room socket, where I was planning to insert the new cable as it has a break in earth. To be absolutely certain that these two sockets are connected, I grabbed the neutral and live of the same cable and checked continuity on these (on the bedroom socket), I expected this to fail as the socket on the other end (living room) was in tact and hence wired in the conventional manner i.e. no connection between live and neutral I thought? However, this was reporting continuity across live and neutral on both wires in the bedroom socket. I am sure there will be a plausible reason for this but this caused me real confusion. I would love to hear an explanation for this…
• I then unwired the socket in the living room. This is the socket I believed the bedroom socket was connected to. I unwired this and had the cables hanging in the air
• I then checked the live and neutral on the bedroom socket again. Now it worked as expected. No continuity reported across Live and Neutral on the same wire. When I joined the live and neutral at the newly removed socket in the living room, I got continuity. I then tried live and earth - nothing. Neutral and earth - nothing. This had me convinced that I had two sockets next to each other on the ring and this is where the earth break was.
• As a further test, I used my wonder lead and connected it to the incoming Earth on the living room socket and then to the incoming earth in the bedroom. After doing this, I tested continuity on the hallway socket again, everything tested successfully.
• With this established, I then started removing the floor boards in the bedroom - in anticipation of checking if the break was within the floor board or alternatively, I was planning to replace the entire cable (in the wall, down to the living room). This is where the plot thickened!
• The cables under the floor boards suggested that the bedroom socket wasn't connected to the living room socket. The cable was clearly going to and coming from different sockets. Incidentally, the bedroom socket was receiving it's connection from a socket near the living room socket in question (but not that one). To avoid confusion, let's call this socket the TV socket. This TV socket was then going to the living room socket.
• I then unwired the TV socket and had the wires hanging in the air. At this point the earlier testing with live and neutral (between bedroom and living room sockets), no longer worked. It was clearly only working because the TV socket was providing some sort of circuit but again, I don’t understand why the live and neutral would return continuity in this situation….
• I then did the live and neutral (on same wire) test between the bedroom and TV socket and this returned continuity. I could also see that the earth break was between the TV socket and the Living room socket
• I then terminated this cable at both ends (living room and TV sockets) with a 3 way wago and inserted a new cable between these two sockets
• After doing this, I connected up all sockets apart from the one in the landing. I returned here for one final continuity test across all 3 wires and it was successful
• Finally, I energised the circuit, tested all the sockets with a socket tester and everything appears to be fine.

This was a far cry from the simple resolution I was anticipating but importantly, it has left me with unanswered questions - as you can see from the above.

Look forward to your wisdom on this matter. Thanks again.

 

[davelx]

I then checked the live and neutral on the bedroom socket again. Now it worked as expected. No continuity reported across Live and Neutral on the same wire. When I joined the live and neutral at the newly removed socket in the living room, I got continuity. I then tried live and earth - nothing. Neutral and earth - nothing. This had me convinced that I had two sockets next to each other on the ring and this is where the earth break was.

There could be any number of other sockets between the two that you checked. To be sure, you really have to disconnect ALL the sockets AND the connections in the CU and then buzz out each cable end to find where its other end goes to. ie join L.N & E at one end of one cable only starting at the CU, then find the other end - you can check L,N & E continuity from one end, as you have linked them all at the other end. Then mark the cables, remove the links and repeat for the next leg, etc.etc. Then you will know the exact order in which the sockets are wired. It sounds more time consuming than it actually is.

 

[Harry Bloomfield]

There could be any number of other sockets between the two that you checked. To be sure, you really have to disconnect ALL the sockets AND the connections in the CU and then buzz out each cable end to find where its other end goes to. ie join L.N & E at one end of one cable only starting at the CU, then find the other end - you can check L,N & E continuity from one end, as you have linked them all at the other end. Then mark the cables, remove the links and repeat for the next leg, etc.etc. Then you will know the exact order in which the sockets are wired. It sounds more time consuming than it actually is.

There also might be hidden joint boxes under the floors.

 

[SUNRAY]

Hi All,

I embarked on these changes earlier in the week and have come away with more questions than I started with...
None of my previous testing made any sense and I spent half the day testing again. I was hoping to do a quick verification of the previously identified faults and then move straight to making the necessary changes. Felt like I was in a different house! I am desperately trying to recall the confusion I faced as I wanted to make sense of it all afterwards. I am hoping you can solve a few puzzles for me. Here’s my recollection of events.

• Started by locking off the MCB for the affected ring
• Ran around with socket tester and all went to plan. This identified the sockets on this ring.
• Removed a random socket (landing) on the ring. Different to the one I removed previously
• I grabbed the ends of live and live - continuity was good. Same on neutral and no continuity on earth. Again, as noted in EICR
• I then went to the socket upstairs (bedroom) where I was convinced the earth break was (between here and the living room). Unscrewed the bedroom socket and had the cables hanging in the air. I wanted to double check that this is definitely and directly connected to the living room socket, where I was planning to insert the new cable as it has a break in earth. To be absolutely certain that these two sockets are connected, I grabbed the neutral and live of the same cable and checked continuity on these (on the bedroom socket), I expected this to fail as the socket on the other end (living room) was in tact and hence wired in the conventional manner i.e. no connection between live and neutral I thought? However, this was reporting continuity across live and neutral on both wires in the bedroom socket. I am sure there will be a plausible reason for this but this caused me real confusion. I would love to hear an explanation for this…
• I then unwired the socket in the living room. This is the socket I believed the bedroom socket was connected to. I unwired this and had the cables hanging in the air
• I then checked the live and neutral on the bedroom socket again. Now it worked as expected. No continuity reported across Live and Neutral on the same wire. When I joined the live and neutral at the newly removed socket in the living room, I got continuity. I then tried live and earth - nothing. Neutral and earth - nothing. This had me convinced that I had two sockets next to each other on the ring and this is where the earth break was.
• As a further test, I used my wonder lead and connected it to the incoming Earth on the living room socket and then to the incoming earth in the bedroom. After doing this, I tested continuity on the hallway socket again, everything tested successfully.
• With this established, I then started removing the floor boards in the bedroom - in anticipation of checking if the break was within the floor board or alternatively, I was planning to replace the entire cable (in the wall, down to the living room). This is where the plot thickened!
• The cables under the floor boards suggested that the bedroom socket wasn't connected to the living room socket. The cable was clearly going to and coming from different sockets. Incidentally, the bedroom socket was receiving it's connection from a socket near the living room socket in question (but not that one). To avoid confusion, let's call this socket the TV socket. This TV socket was then going to the living room socket.
• I then unwired the TV socket and had the wires hanging in the air. At this point the earlier testing with live and neutral (between bedroom and living room sockets), no longer worked. It was clearly only working because the TV socket was providing some sort of circuit but again, I don’t understand why the live and neutral would return continuity in this situation….
• I then did the live and neutral (on same wire) test between the bedroom and TV socket and this returned continuity. I could also see that the earth break was between the TV socket and the Living room socket
• I then terminated this cable at both ends (living room and TV sockets) with a 3 way wago and inserted a new cable between these two sockets
• After doing this, I connected up all sockets apart from the one in the landing. I returned here for one final continuity test across all 3 wires and it was successful
• Finally, I energised the circuit, tested all the sockets with a socket tester and everything appears to be fine.

This was a far cry from the simple resolution I was anticipating but importantly, it has left me with unanswered questions - as you can see from the above.

Look forward to your wisdom on this matter. Thanks again.

From the way this is written I think you are indicatiing more difficulty fault finding than I'm comfortable with, for a start you seem to be struggling to even identify which circuits your sockets are on (as per your confirmation of my post with a sketch of circuit and IIRC you isolated the whole of the house apart from this circuit too) and additionally you seem to have ignored advice offered previously, I could have missed detail as I have not just double checked 2 weeks worth of posts.

I'm even beginning to wonder if your EICR was incorrect and the possibility that you are looking for a fault that doesn't exist.

Dave has generously offered further advice, similar to some given before.

There could be any number of other sockets between the two that you checked. To be sure, you really have to disconnect ALL the sockets AND the connections in the CU and then buzz out each cable end to find where its other end goes to. ie join L.N & E at one end of one cable only starting at the CU, then find the other end - you can check L,N & E continuity from one end, as you have linked them all at the other end. Then mark the cables, remove the links and repeat for the next leg, etc.etc. Then you will know the exact order in which the sockets are wired. It sounds more time consuming than it actually is.

I would have offered that you have reached the stage you need the services of someone with better fault finding experience.

 

[Jupiter01]

There could be any number of other sockets between the two that you checked. To be sure, you really have to disconnect ALL the sockets AND the connections in the CU and then buzz out each cable end to find where its other end goes to. ie join L.N & E at one end of one cable only starting at the CU, then find the other end - you can check L,N & E continuity from one end, as you have linked them all at the other end. Then mark the cables, remove the links and repeat for the next leg, etc.etc. Then you will know the exact order in which the sockets are wired. It sounds more time consuming than it actually is.

Apart from untoward wiring, what causes the neutral+live cables to show continuity in the way that I have experienced? I assumed that N+L don't ever connect and hence, I shouldn't be seeing continuity across these unless I am deliberately joining them to establish the cable path. This was my main confusion.

 

[Jupiter01]

for a start you seem to be struggling to even identify which circuits your sockets are on

The sockets on the circuit hasn't changed between my earlier post and most recent investigations. I repeated this step to be sure I've not missed anything.

you seem to have ignored advice offered previously,

Which advice? I was intending to implement your suggestion until I learnt about the TV socket - through the additional testing I undertook on the day. Please let me know if I have missed something.

I'm even beginning to wonder if your EICR was incorrect and the possibility that you are looking for a fault that doesn't exist.

I think the EICR is correct because one of my initial steps (documented above) was to check continuity across all three wires. In this test I can see that there is no continuity across Earth.

 

[SUNRAY]

The sockets on the circuit hasn't changed between my earlier post and most recent investigations. I repeated this step to be sure I've not missed anything.


Which advice? I was intending to implement your suggestion until I learnt about the TV socket - through the additional testing I undertook on the day. Please let me know if I have missed something.


I think the EICR is correct because one of my initial steps (documented above) was to check continuity across all three wires. In this test I can see that there is no continuity across Earth.

Except

View attachment 235967
As I read it this is the current set-up.
Green and blue cables are good, Red is bad and to be abandoned.

spot on!

Are there any other sockets...?

No other sockets.

Now I believe you are referring to bedroom socket, tv socket and lounge socket.

I should mention that if the CU main switch and all MCB are switched off and you test for continuity between sockets on different circuits they will appear to be open circuit between L's and I think I've seen that test in there somewhere. It may not be, but your long post felt a little confusing.

Quite early on I recall someone advising you to isolate and short L, N & E together to do your tests, I don't recall the results.

We are able to offer lots of advice based on years of experience in some very complex situations. I'm sure I speak for many by saying I hate to not be able to get someone right through to a successful conclusion with my advice but we are unable to perform miracles.

I apologise but feel my advice is now to call someone in.

 

[Jupiter01]

Understood and thanks @SUNRAY

I should mention that if the CU main switch and all MCB are switched off and you test for continuity between sockets on different circuits they will appear to be open circuit between L's and I think I've seen that test in there somewhere. It may not be, but your long post felt a little confusing.

Can I have some clarification on this please. If we take any Ring circuit, switch it off at the MCB, whip off a socket and have the cables hanging in the air. What would lead to there being continuity across L and N on the same cable?

 

[JohnD]

continuity across L and N on the same cable?

something being plugged in.

 

[Jupiter01]

something being plugged in.

Would an FCU with a fuse also have the same effect?

Baring the above, is there any reason why a ring circuit with nothing plugged in (nor with any FCU's depending on your answer to the above) would report continuity across the L&N on the same cable? I don't think it's the case but wanted to understand if there was anything behind the socket or in the CU that causes the L&N to connect and hence report continuity in the test I am describing.
The answer to this will help me understand this principle.

 

[JohnD]

Would an FCU with a fuse also have the same effect?

only if some load was connected to it.

is there any reason why a ring circuit with nothing plugged in... would report continuity across the L&N on the same cable?

fault? not otherwise

Not sure what a neon would do when below strike voltage.

 

[securespark]

I had open circuit across all 3 conductors on a ring final once. Went round and found one with only one cable in.

Went under the floor and found the missing leg just hanging in space as if it had been pulled out from the socket with one cable in.

 

[Jupiter01]

only if some load was connected to it.

and switched on if it's a switched FCU?

Not sure what a neon would do when below strike voltage.

Sorry, I don't understand this. Can you elaborate please.

Went under the floor and found the missing leg just hanging in space as if it had been pulled out from the socket with one cable in.

Presumably, my socket tester would identify this when testing on the energised circuit?