Faulty ring main

[aaronstuart]

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Not great on fault finding, in fact hardly done any.

Problem is a ring main.

r1 = 1.10 ohms
r2 = 1.38 ohms
rn = 1000 ohms???????

All tests done at cu cables disconnected.
what's going to be the correct course of action to find fault?

Just go around and check wiring in back of sockets etc or could i link N/cpc of 1 leg and go round?


Help needed thanks

 

[PAUL M]

well for a start you may have a loose connection on your neutrals,but your r1,r2 values are out allso if you getting r1 =1.10 ohms your r2 should be around 1.83 ohms assuming cpc is 1.5 mm,if i was you i would start by taking all your sockets off and check connections.is it one ring for entire house.

 

[aaronstuart]

old victorian house.
ring covers downstairs lounge.
another ring covers upstairs, loft and kitchen / new extension which was done last year.

all the certifcates that was issued were incorrect.......
wrong cable size, wrong fuses, lighting they had put 30ohms when there was no earth.....and all metal fittings and switches...
obviously informed customer and hopefully will sort it.

will remove all and check connections

 

[sparky1ste]

i agree with paul -however the neutral is open and the r1 + r2 is far to high.all sockets off on that circuit checking for tightness.[you may come across the open neutral aswell as the loose connections in one socket]
the readings on average should be anywhwere between 0.22 -0.60[depending how many sockets]for r1/rn and 1.67 times higher foe cpc[1.5mm]
eg.0.30x1.67=0.50 add 0.30 then divide by 4=0.20-test at sockets to see if 0.20 is the reading approx you are getting.if not it could be spur on a spur or 2 rings [loop] on 1 ring main circuit.

 

[aaronstuart]

thanks for help will do what you advise

 

[EasyFox]

Had the same on 2x ring finals Saturday at same property

Ring one (kitchen)
r1 670 (o/c when microwave & fridge unplugged)
traced to dissconnected line leg at socket in utillity room. Conductor had been stripped & folded back into the backbox.

ring two rest of house
r1 >800 (went o/c when all items unplugged off circuit)
Again same as other ring, line conductor stripped & folded back into the backbox.

Reconnected both & all was fine ring one r1 now at 0.42 & ring two now at 0.56

Sad thing is kitchen is a new circuit(installed when kitchen was fitted) & ring 2 was an extension of existing circuit, both were installed by a part P approved kitchen fitter from MFI back in January, no certs & customer said the 2 blokes that were doing the work didnt seem to have a clue & didnt come back to connect the 2x radial sockets in the lounge (connected at cu but terminal blocks wrapped in tape loose on floor).