I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms. Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?

--
Chris Green
·

On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms. Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.

--
Adam

On 04/08/2019 09:20, ARW wrote:
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms.Â* Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.


"each other"

What are you using to do the test?

--
Adam

Of course on such low values, connections even in the tester itself can put
them way out.
Brian

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"ARW" wrote in message
...
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms. Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.

--
Adam

ARW wrote:
On 04/08/2019 09:20, ARW wrote:
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms.Â* Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.


"each other"

What are you using to do the test?

A pretty good multimeter which consistently reads 0.0 ohms when the
leads are shorted together. I have also used another (less good)
multimeter and got pretty similar results.

So I should look for an issue somewhere. The meter has good enough
discrimination I think so that I can split the ring in the middle
somewhere and try measuring the two halves and do a 'binary chop'
until I find the problem.

--
Chris Green
·

Brian Gaff wrote :
Of course on such low values, connections even in the tester itself can put
them way out.

Correct, it is even difficult to get a decent contact with the probes
for such low values of resistance. The meter needs to have good firm
connections and support at least two digits after the decimal point to
produce a worthwhie result.

On 04/08/2019 10:35, Chris Green wrote:
ARW wrote:
On 04/08/2019 09:20, ARW wrote:
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms.Â* Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.


"each other"

What are you using to do the test?

A pretty good multimeter which consistently reads 0.0 ohms when the
leads are shorted together. I have also used another (less good)
multimeter and got pretty similar results.

So I should look for an issue somewhere. The meter has good enough
discrimination I think so that I can split the ring in the middle
somewhere and try measuring the two halves and do a 'binary chop'
until I find the problem.


I would say there is an issue.

I would just say check the tightness of all the socket terminals and not
bother with divide and conquer on this one as there may be more than one
at fault. How many sockets/fused spurs are there?

And remember to check the CU terminals.

--
Adam

ARW wrote:
On 04/08/2019 10:35, Chris Green wrote:
ARW wrote:
On 04/08/2019 09:20, ARW wrote:
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms.Â* Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.


"each other"

What are you using to do the test?

A pretty good multimeter which consistently reads 0.0 ohms when the
leads are shorted together. I have also used another (less good)
multimeter and got pretty similar results.

So I should look for an issue somewhere. The meter has good enough
discrimination I think so that I can split the ring in the middle
somewhere and try measuring the two halves and do a 'binary chop'
until I find the problem.


I would say there is an issue.

I would just say check the tightness of all the socket terminals and not
bother with divide and conquer on this one as there may be more than one
at fault. How many sockets/fused spurs are there?

Probably around 20 or so, maybe a few more than that.


And remember to check the CU terminals.

Well they've been on and off several times for the measurements! :-)

--
Chris Green
·

On 04/08/2019 16:29, Chris Green wrote:
ARW wrote:
On 04/08/2019 10:35, Chris Green wrote:
ARW wrote:
On 04/08/2019 09:20, ARW wrote:
On 04/08/2019 08:29, Chris Green wrote:
I have just been working on our electrics and, among other things,
removed some sockets from a ring circuit as they were on a stud wall
which will soon be removed.

While I was about it I checked the end-to-end continuity of the live
and neutral conductors, they were OK but measured slightly different,
one was about 0.6 ohms, the other about 0.8 ohms.Â* Should I be worried
and start checking for loose terminal screws or similar or is this
difference within the variability one might expect?


The readings should be within 0.05 ohms of each on a T&E circuit.


"each other"

What are you using to do the test?

A pretty good multimeter which consistently reads 0.0 ohms when the
leads are shorted together. I have also used another (less good)
multimeter and got pretty similar results.

So I should look for an issue somewhere. The meter has good enough
discrimination I think so that I can split the ring in the middle
somewhere and try measuring the two halves and do a 'binary chop'
until I find the problem.


I would say there is an issue.

I would just say check the tightness of all the socket terminals and not
bother with divide and conquer on this one as there may be more than one
at fault. How many sockets/fused spurs are there?

Probably around 20 or so, maybe a few more than that.


And remember to check the CU terminals.

Well they've been on and off several times for the measurements! :-)


With that number I would just check them all.

--
Adam