ring final continuity fault

[the_mouse]

Hi, got an open circuit on the nuetrals of my socket circuit (line and cpc OK) have checked socket outlets cant find a loose/ broken connections, whats the method of locating this fault. (adult trainee and have test instuments)

thanks in advance

 

[Andy™]

seperate neutrals at DB. use a continuity with long lead. connect one end to a neutral. work round sockets. readings will be non-existant on side, and readings getting higher on other side. fault will be between highest readings from both sides

 

[ianmacd]

Assuming its a dead circuit, then I would disconnect the N's and the cpc's at the CCU and connect one cpc to one N (from the same T&E) and then go to each socket and check the continuity of cpc to N and when you find one that is open its after the broken N.

Once you have found the start of the fault you should try and trace the cable back towards the CCU to the previous accessory and then check (probably with a wander lead) the continuity of the N between these 2 accessories. If its a faulty cable then it either will need to be replaced or possibly turned into 2 radials (possibly using the same MCB) with a suitably sized protective device. It may not be the cable and just a bad connection in the back of one of the accessories and may just need reterminating/refixing.

Ian.

 

[Evans Electric]

As the other two have said , the object is to narrow it down untill you know its between two points .

 

[the_mouse]

Thanks guys will try again tomorrow, found a socket outlet hidden behind a radiator! drained it down removed it checked s/o it was ok headbang , things are never simple

 

[paul b b]

you never know, a socket could have been taken away and cables in a JB somewhere under the floorboards. good luck!

 

[SPECIAL LOCATION]

Hi, got an open circuit on the nuetrals of my socket circuit (line and cpc OK) have checked socket outlets cant find a loose/ broken connections, whats the method of locating this fault. (adult trainee and have test instuments)thanks in advance

Hello Mouse...

Adding a bit more thought to the other guys posts you need to be thinking....

• Is it 'open circuit' or a 'High resistance'?
  
• Is it 'One' Neutral break or 'Two (or more)' Neutral breaks?
  

If it was me I would do the following

1/ Make sure EVERYTHING on the circuit is unplugged disconnected & switched off to avoid any false - misleading readings.

2/ Disconnect both T&E ends of ring from CU

3/ Do an Insulation resistance test @ 250v across L-E, N-E, L-N at both ends of the rings T&E's just to check all is unplugged & disconnected.

4/ Do an insulation resistance test round the broken ring leg... i.e. 'N' to 'N' on each of the T&E's to see if it is absolutely open circuit or just very high resistance.

5/ If 4 is showing a high resistance reading, double check your Live & Earth continuity resistance readings (the know good legs) and calculate an approx length using the ohms per meter table on page 166 of OSG. to check if both the existing continuity reading are approx right or is one of these also a bit to high.. (could be an indication of dodgy joint somewhere)

6/ To establish if you are looking for One Neutral break or Two (or more) Neutral breaks...

In a similar fashion to what Ian said Join 'N' & 'E' on one of the T&E ring ends....

But also join 'L' & 'N' together on the other T&E ring end. (Wago lever connectors are good or that bit)

7/ Go around all of the socket / accessory outlets and take a continuity reading between 'L' - 'N' then 'N' - 'E'. Every outlet should have either a 'L'-'N' continuity for a 'N'-'E' continuity.

8/ If an outlet position has neither 'L'-'N' OR 'N'-'E' continuity then there is probably two breaks in the N ring.

9/ If every outlet does have a continuity between either 'L'-'N' OR 'N'-'E' then the fault is somewhere between the two outlets with the highest continuity readings.

Guinness

 

[mikel]

specs

I see what your method is but have you miss typed the connection for the second T/E at step 6? Should it not read connect L to N. You've put connect L to E. I think in the way you have said connect them you wouldn't get a reading between L&N at each outlet.

Or should I just :coat

 

[Theorysparky]

Sketch the layout of the ring

disconnect both t+e at the D/B

connector block L-N on one t+e

go to all outlets testing for continuity recording results on the sketch

repeat for the other t+e using different colour pen or circle the reading

there should be a highest reading on both legs before open cct

between both readings will be your fault on the nuetral

then look for the obvious diy job,,,,,,curtain rail,,,,,picture hook,,shelf

always draw a diagram it always helps

 

[the_mouse]

Quick update, disconnected both T&E from board and connected Line and Nuetral of leg 1 together when checking for continuity i got continuity at each outlet! but not at board so could be cable from last outlet to the consumer unit.

The meter readings were not what i expected ranging from 0.19ohm to 0.60ohm but a socket outlet which i know is a spur gave a reading of 012ohm the lowest reading! thought it would be higher.

 

[vandalay]

Could these readings and the continuity at sockets indicate a interconnected ring?

 

[ianmacd]

Did you connect the other leg and try that too?

Ian.

 

[SPECIAL LOCATION]

specsI see what your method is but have you miss typed the connection for the second T/E at step 6? Should it not read connect L to N. You've put connect L to E. I think in the way you have said connect them you wouldn't get a reading between L&N at each outlet.

Or should I just :coat

oh.....Applaud SmileyApplaud SmileyApplaud SmileyApplaud Smiley

Applaud SmileyApplaud SmileyGuinness

No ... No... No... No!!!

you are 100% right there Mikel.....

(glad you spotted my deliberate mistake BlushingBlushingO)Pray)

nice to think clever bods like you are actually reading my drivel! ; \ ]

I blame the Free Beer Admin keeps handing out!!!!

GuinnessGuinnessGuinnessGuinness

In my defence you honour it was 2:23 when I wrote it!!!! :^O

I believe you have the right to go and get the big wet haddock from Admins cupboard and give me 30 lashings with the fish! :_|

ROTFWLROTFWL

 

[SPECIAL LOCATION]

Quick update, disconnected both T&E from board and connected Line and Nuetral of leg 1 together when checking for continuity i got continuity at each outlet! but not at board so could be cable from last outlet to the consumer unit.The meter readings were not what i expected ranging from 0.19ohm to 0.60ohm but a socket outlet which i know is a spur gave a reading of 012ohm the lowest reading! thought it would be higher.

L-N 2x2.5mm legs (14.82mohm/m from table 9A page166 OSG)

(0.19ohm / 14.82) x 1000 = approx 12.8m from you joined legs.

(0.60ohm / 14.82) x 1000 = approx 40.5m from your joined legs.

(0.12ohm / 14.82) x 1000 = approx 8.1m from your joined legs.

ONLY you would know if these lengths are feasible on the installation! :|

Although your "know spur" would on a RING be a higher value when BOTH 'L's and BOTH 'N's are joined...

If you have split your ring open and only joined one end, you will be getting reading in a similar fashion as with a RADIAL circuit.

so your spur could be nearer to your test looped legs and so would be lower resistance than other outlets further along the radial branch!

Try the same outlets with L-E looped

these "should" give approx values of...

0.25ohm

0.79ohm

0.16ohm

IF the CPC is 1.5mm!

Guinness