ring main problem

[davidjones89]

Advice needed on this please, testing a property today and came across a problem with ring main. End to end readings of conductors showing no continunity of line-line and cpc-cpc, neutral is showing continunity. broken ring main on two of the conductors, house is wired as one complete ring main for upstairs and down. there is evidence of alterations to property with an extension etc and the odd jb discovered under floorboards.Tested continunity at sockets by linking line/cpc at db and marked sockets with tape where readings were taken then swapped over to other leg and tested continunity of the other sockets and noted readings. checked at the back of sockets in case any of the conductors had fallen out but all seem ok. without stating the obvious about broken ring mains has anyone come across this before with the neutal the only one showing continunity, could the cable be broken withthe neutral core just still attached seems a long shot but before i start lifting carpets and floors just want to make sure i'm not missing something else

 

[SirKit Breaker]

Advice needed on this please, testing a property today and came across a problem with ring main. End to end readings of conductors showing no continunity of line-line and cpc-cpc, neutral is showing continunity. broken ring main on two of the conductors, house is wired as one complete ring main for upstairs and down. there is evidence of alterations to property with an extension etc and the odd jb discovered under floorboards.Tested continunity at sockets by linking line/cpc at db and marked sockets with tape where readings were taken then swapped over to other leg and tested continunity of the other sockets and noted readings. checked at the back of sockets in case any of the conductors had fallen out but all seem ok. without stating the obvious about broken ring mains has anyone come across this before with the neutal the only one showing continunity, could the cable be broken withthe neutral core just still attached seems a long shot but before i start lifting carpets and floors just want to make sure i'm not missing something else

Unfortunately i have been there and done that all too often. There could be all sorts of dodgy DIY jobs under the floor etc. Its sounds to me like at some point mr DIY has connected something into the ring and used some dodgy method of connection, this is now coming apart and maybe in more places than one. I'm afraid that it looks like you are going to have to go through this circuit with a fine toothcomb to find out what has happened. The fact that RN is giving you a reading suggests that it was once a ring. Completely disconnect all the accessories and try to find where you are losing the continuity, then start to try find what is between the 2 points where you lose it. Good luck and keep us posted.

Cheers.............Howard

 

[TPES]

I've had the same problem just 2 days ago,

1 ring doing complete house, I had continuity on both the line and cpc but nothing end to end on the neutral!!

Customer was saying they lost almost all power to the house but 3036 fuse had not blown,

I tested out for 230v across L-N at each socket fine but not on the return at the CU.

So I had a good assumption there was a neutral break from the CU to last (or first) socket on the ring, there is a bit of length on this with wood laminate floor in everyroom, I have tempory put a 20a trip on the board mainly to protect the cable, I have explained they could have overloading problems though untill I have found the break in neutral.

 

[GStueyXR]

measure continuity between one socket and the next.... Isolating problem...

 

[Mark_Burgess]

Either as mentioned a junction box, or as I found a few months back, a nail that was through a dado rail holding it to the wall and into a cable!!

 

[Andyfm]

Had to find similar faults in the past, and once or twice have found a fixing hole for kitchen units or to hang a picture or a curtain pole had been drilled through the cable and went straight through one, sometimes two cores, blowing the fuse or mcb, but not causing a permanent short circuit, then the fuse was replaced by the dodgy DIYer without investigating the damage, so have a look for pictures/mirrors above sockets once you`ve found the section of the circuit at fault

 

[davelerave]

Had to find similar faults in the past, and once or twice have found a fixing hole for kitchen units or to hang a picture or a curtain pole had been drilled through the cable and went straight through one, sometimes two cores, blowing the fuse or mcb, but not causing a permanent short circuit, then the fuse was replaced by the dodgy DIYer without investigating the damage, so have a look for pictures/mirrors above sockets once you`ve found the section of the circuit at fault

good point

 

[nickblake]

i had one that had a high coninuity reading ,4.3 ohms on a relativly small ring this was on N and CPC (cpc was 6.4 ohms ) lifted floor boards loads of junction boxes checked them all all ok removed every socket well i thought , so i did the test from each direction of the ring joind L an CPC to gether and went round the ring socket by socket 0.15 on one end then traced to one leg , thought the cable was down untill i spotted a socket behind a radiator cut jointed and was all ok