A.Lee wrote:
I've done a bit of testing this afternoon, and found a fault on a ring
main.
Continuity results:
E-E 0.40 ohms
N-N 0.19 ohms
L-L 37 ohms - clearly a fault here.

I checked the 4 sockets on the ring for loose connections, and found
no apparent fault.
So next I joined up opposite ends of L+E, and measured R1 + R2 at the
sockets: 0.42 ohms, 0.42, 0.48, and 0.51ohms.

Clearly the resistance goes up as the sockets get further away.

Muddled thinking got me nowhere.
After a while, I was thinking that the cable must be damaged between
the final socket and the return cable.
But, a resistance of 37 ohms? That doesnt seem to be enough to be a
damaged cable.
(Insulation resistance was checked, and all fine at 1k M ohms)

Any thoughts?
Ta
Alan.


You have actually answered your own question.

Split the ring at all 4 sockets and use a fly lead of known resistance to
check both ends of r1 from the CU before adding sockets as you work to
confirm the topology of the circuit.

It is a damaged cable or an unknown juction box or socket that is at fault.

--
Adam