[A.Lee]

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.

--
To reply by e-mail, change the ' + ' to 'plus'.

[harry]

On Jan 14, 5:55*pm, (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.

--
To reply by e-mail, change the ' + ' to 'plus'.

99% of faults are behind/on a socket. Are you sure you've found them
all. Have you removed the socket to test the cable, could be a faulty
socket switch?

[Skipweasel[_2_]]

In article 7325a866-ef54-42c5-9586-
, says...
99% of faults are behind/on a socket. Are you sure you've found them
all. Have you removed the socket to test the cable, could be a faulty
socket switch?


How would a socket-switch affect the ring continuity?

--
Skipweasel - never knowingly understood.

[Harry Bloomfield[_3_]]

A.Lee explained on 14/01/2011 :
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.

Connect to one end of the ring live with the ring parted, then work
your way along with a long wire with a 13amp plug fitted temporarily on
the end - check each socket in turn, until you find a sudden variation
in impedance. That should make localising it easier.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

[ARWadsworth]

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

[Richard Russell]

On Jan 14, 5:55 pm, (A.Lee) wrote:

But, a resistance of 37 ohms? That doesnt seem to be enough to be a
damaged cable.

Are you sure you disconnected *every* appliance on the ring? I once had a
very similar fault, and like you was puzzled at the measured loop
resistance of a few tens of ohms, but it went up to the expected
'infinity' when everything was properly disconnected. A wire had come
astray behind a socket outlet.

Richard.
http://www.rtrussell.co.uk/

[harry]

On Jan 14, 6:52*pm, Skipweasel wrote:
In article 7325a866-ef54-42c5-9586-
, says...

99% of faults are behind/on a socket. Are you sure you've found them
all. Have you removed the socket to test the cable, could be a faulty
socket switch?

How would a socket-switch affect the ring continuity?

--
Skipweasel - never knowingly understood.

He may not have removed the sockests from the wiring and be testing
from the front of the sockets.

[ARWadsworth]

harry wrote:
On Jan 14, 6:52 pm, Skipweasel wrote:
In article 7325a866-ef54-42c5-9586-
,
says...

99% of faults are behind/on a socket. Are you sure you've found them
all. Have you removed the socket to test the cable, could be a
faulty socket switch?

How would a socket-switch affect the ring continuity?

--
Skipweasel - never knowingly understood.

He may not have removed the sockests from the wiring and be testing
from the front of the sockets.

The clue is in the words "ring continuity":-)

You don't test that from the front of the socket!

--
Adam

[Skipweasel[_2_]]

In article ,
says...
99% of faults are behind/on a socket. Are you sure you've found them
all. Have you removed the socket to test the cable, could be a
faulty socket switch?

How would a socket-switch affect the ring continuity?

He may not have removed the sockests from the wiring and be testing
from the front of the sockets.

The clue is in the words "ring continuity":-)

You don't test that from the front of the socket!

I'm glad someone's awake.


--
Skipweasel - never knowingly understood.

[A.Lee]

ARWadsworth wrote:

Tried replying by email, but your address is dead:

Final-Recipient:
Action: failed
Status: 5.0.0 (permanent failure)
Remote-MTA: dns; [209.85.227.27]
Diagnostic-Code: smtp; 5.1.0 - Unknown address error 550-'5.2.1 The
email account that you tried to reach is disabled. 34si4611472wba.45'
(delivery attempts: 0)

You say "Clearly the resistance goes up as the sockets get further away."
and make it sound as if you did not expect that to happen.


Yes, I was trying to say it was like a radial where the resistance got
higher as I went along, but it did not go down as I progressed back
toward the CU, so the theory of the break between the last socket and
the CU holds some weight.
2 of the sockets have faulty outlets, so I'll change them on Tuesday
when I go back, and I'll do some further testing to pin down where the
fault is.
Thanks
Alan.

--
To reply by e-mail, change the ' + ' to 'plus'.

[ARWadsworth]

"A.Lee" wrote in message
...
ARWadsworth wrote:

Tried replying by email, but your address is dead:

Final-Recipient:
Action: failed
Status: 5.0.0 (permanent failure)
Remote-MTA: dns; [209.85.227.27]
Diagnostic-Code: smtp; 5.1.0 - Unknown address error 550-'5.2.1 The
email account that you tried to reach is disabled. 34si4611472wba.45'
(delivery attempts: 0)

You say "Clearly the resistance goes up as the sockets get further away."
and make it sound as if you did not expect that to happen.


Yes, I was trying to say it was like a radial where the resistance got
higher as I went along, but it did not go down as I progressed back
toward the CU, so the theory of the break between the last socket and
the CU holds some weight.

It certainly does, either that or an odd topology,

2 of the sockets have faulty outlets, so I'll change them on Tuesday
when I go back, and I'll do some further testing to pin down where the
fault is.

Well it will obviously be the last cable you test!
--
Adam