Advice Needed : Strange ring main readings

[nelly29]

Hi

Currently in my 2nd year at college, and as you do been testing at my own house.

I started testing a ring final circuit, the only 1 for the entire house , r1 0.58 ohms, rn 0.58 ohms then when i went to test r2 ( end to end ) the reading was 60.0 k ohms on my megger mft1553

Checked all sockets and everything seems ok, even looked for junction boxes hidden away.

Supply in tnc-s, bonding ok, 17th edition split board


Any help would be appreciated, and go easy as i'm new!

Thanks

Dave

 

[Guest123]

Hi.

Are you 100% sure you had the correct cpc's for the ring from the earth bar???, just because they were in the same terminal doesn't mean they are the correct ones for the ring, they may have just been put in any old shape previously.

If so then it sounds like a very high resistance joint on a cpc connection somewhere there..........at a socket most likely, or as you say a hidden JB.

Have you checked the terminations at all the sockets, and that the sleeving isn't pushed into the terminal aswell???

 

[nelly29]

Hi
Yeah made sure i had correct cpc's for the ring, been round and checked all the sockets made sure terminations were in and tight.
I forget to mention i tested earth fault loop impedance (zs) at the sockets with my megger and got varied readings of 0.76 ohms upto 1.79 ohms.

i bet there's a junction box under a floor board somewhere, just my luck!

Thanks for the reply

 

[dufjax]

Hi
Yeah made sure i had correct cpc's for the ring, been round and checked all the sockets made sure terminations were in and tight.
I forget to mention i tested earth fault loop impedance (zs) at the sockets with my megger and got varied readings of 0.76 ohms upto 1.79 ohms.

i bet there's a junction box under a floor board somewhere, just my luck!

Thanks for the reply

Were all the reading varied or were some 0.76 and a couple higher? or did they seem to go up as you went round?

Jim

 

[pennywise]

Split the ring in two in the middle somewhere, with a wander lead back to the board do your resistance readings again find the faulty leg. Put the conductors of the faulty at the socket in block or wagos leave the good leg terminated in the socket, take the faulty leg out from the breaker put these in blocks as well liven up the good leg see what stays off then you should have a better idea of in what order the sockets where wired If there not all JBs. Isolate circuit again and start disconnecting one socket at a time from the faulty leg split the earths and work backwards with the wander lead until reading improves then hopefully this will narrow the area down as to where to look Oh and always draw a diagram far easier to remember what wiring between sockets is Ok tick them off when you've tested them, I have a bad memory. Apologies If I'm completely wrong and you've done all this it's been a long day

 

[nelly29]

thanks for the advice, i will try it tomorrow.

cheers dave

 

[Jason Smith]

Do a R1 plus R2 at the board, cross connected. Leave Connected at the board. Then go to each socket, and do the same, with a socket interface adaptor. DO BOTH SIDES OF THE DSO'S. See what you find out.

I mean leave the connection in place at the board, obviously its a dead test.

Must add was everything uplugged from the sockets to mate ?