Ring CPC fault

[humpa]

Hi guys, first time I have posted on the site so looking forward to hearing from you all. I am carrying out a kitchen refit and while testing the ring circuit I have come across a lack of continuity on the CPC circuit. I have carried out testing using the two ends and a R2 wander lead and have managed to track down the break which is situated somewhere between two socket outlets in the study. To test the continuity I temporarily bridged the two earth points n the sockets with a length of 1.5mm earth flex but then obtained the following results :- r1 0.80, rn 0.78, r2 0.30 furthermore the R1+R2 readings average 0.69 for all sockets except the two in the study which read 0.10. With the bridge left in and the circuit energised the average ZS reading was 1.18 with the two linked sockets reading 0.30. Client not keen on me ripping up the house to find the break but beside that I am confused by the readings I have got. Any ideas guys ?

 

[Pete999]

Have you identified the leg of the RFC which has the broken cpc?

 

[Pete999]

Remove the damaged cable / leg, down rate the OCPD and form 2 radial circuits, 20A

 

[Flanders]

There could be more than i ring coursed by multiple earth connection points caursing parallel earth paths, so in affect you are only testing continuity of a small part of the curcuit try disconnecting both legs of the cpc at at differnt point of the circuit and see if you still have ring continuity

 

[7029 dave]

Never mind your r1 r2, this fault can be identified by basic continuity testing.

 

[humpa]

Thanks for all the replies guys, don't really want to create two separate radials. Want I don't understand is that I have in affect by bridging the two sockets repaired the broken CPC, but the readings for r2 continuity are far lower than r1 and rn ?

 

[Brad1]

Your r1 reading can be low due to supplementary bonding in the property.

 

[telectrix]

Your r1 reading can be low due to supplementary bonding in the property.

did you mean r2. bonding will not affect this .

 

[Pete999]

Your r1 reading can be low due to supplementary bonding in the property.

r1 is the resistance of the live conductor how will supplementary bonding effect that reading, if it's disconnected from the CU?

 

[Brad1]

did you mean r2. bonding will not affect this .

Yeah, I did sorry and If you're testing from a flying lead in the board to a set point remember that the sup' bonding is still on that board and/or "back in the day of JBing every socket" they used to take a single earth to do sup' bondings.

 

[Pete999]

Yeah, I did sorry and If you're testing from a flying lead in the board to a set point remember that the sup' bonding is still on that board and/or "back in the day of JBing every socket" they used to take a single earth to do sup' bondings.

Sorry What?

 

[telectrix]

if trying to measure R2 with a wander lead from DB to point, then you'd dis the cpc from the board to eliminate any parallel paths.

 

[Pete999]

Hi guys, first time I have posted on the site so looking forward to hearing from you all. I am carrying out a kitchen refit and while testing the ring circuit I have come across a lack of continuity on the CPC circuit. I have carried out testing using the two ends and a R2 wander lead and have managed to track down the break which is situated somewhere between two socket outlets in the study. To test the continuity I temporarily bridged the two earth points n the sockets with a length of 1.5mm earth flex but then obtained the following results :- r1 0.80, rn 0.78, r2 0.30 furthermore the R1+R2 readings average 0.69 for all sockets except the two in the study which read 0.10. With the bridge left in and the circuit energised the average ZS reading was 1.18 with the two linked sockets reading 0.30. Client not keen on me ripping up the house to find the break but beside that I am confused by the readings I have got. Any ideas guys ?

http://www.electriciansforums.co.uk...lations/99490-ring-cpc-fault.html#post1067406

This vid tells you how to test a RFC properly

 

[Pete999]

http://www.electriciansforums.co.uk...lations/99490-ring-cpc-fault.html#post1067406

This vid tells you how to test a RFC properly

Sorry don't know what happened will try again

 

[telectrix]

55 PP3 s wired in series if you ain't got a megger to hand.

 

[Geordie Spark]

Take your pick from this plethora of videos!

https://www.google.co.uk/search?q=y...-8&oe=utf-8&gws_rd=cr&ei=NErWVIm9IsbOaOaLgMAI

Isn't Google wonderful???

 

[telectrix]

i call my lady "google"

1. she's always around.
2. she knows everything
3. she's high maintenance

 

[humpa]

Thanks guys, after giving the problem plenty of thought what I need to do is double check that the break in the CPC is actually were I think it is. Otherwise my piece of bridge cable could be forming a mini ring.