High Zs on ring final circuit

[Pete999]

Thanks Murdoch,

I mention before I have mainly done commercial so old school houses are become the norm.

One thing for sure, if I'm not sure the yellow book appears. I also post here to seek everyone's opinions.

Many thanks

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Not sure I understand this reply, is that due to tapatalk?

 

[Octopus]

Thanks Murdoch,

I mention before I have mainly done commercial so old school houses are become the norm.

One thing for sure, if I'm not sure the yellow book appears. I also post here to seek everyone's opinions.

Many thanks

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Did you not test properly doing commercial? Testing is testing irrespective of the type of installation

 

[ian.settle1]

Hi,

R1 = 0.29
Rn = 0.30
R2= 1.30

Measured zs 1.48

The socket in question was a spur, the rest of the ring was highest reading 0.42 r1+r2

OCPD 32amp was on the circuit.

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So the socket in question is a spur of the ring main and not part of the actual ring main?

 

[robo83]

Did you not test properly doing commercial? Testing is testing irrespective of the type of installation

Did mainly metal munching on rail projects. Domestic is another ball game and I'm sure you would respect that although testing is testing it's a bit different when u had Bob the builder playing games compared to a fresh install.

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[robo83]

So the socket in question is a spur of the ring main and not part of the actual ring main?

Yes Ian that's correct.

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[stevethesparks]

But you still have a high r2 on the end to end results as already pointed out by HT.

 

[bensk]

is the spur part of the ring or spurred off? surely something to do with that link if the rest of the ring has low r2

 

[Pete999]

If it was part of the Ring it wouldn't be a spur, would it?

 

[robo83]

It's definitely a spur.

I'm back there today so will sort it.

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[telectrix]

first thing i'd do is investigate the high r2 value. that's end/end of the \RFC and nothing to do with the spur. then i'd do a hi-current Zs bypassing the RCD and MCB to eliminate any internal resistance errors.

 

[robo83]

Thanks Telectrix

If the r1+r2 was fine throught the circuit except the spur. But still getting a high r2 value end to end.

Surly that would mean there is a loose connection on the ring where the spur has been taken?



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[hightower]

Tel, could you explain the process of bypassing the RCD and MCB for the high current test. Would you just link the circuit line to the load side of the main switch temporarily? Anything to keep in mind for this - obviously I would say it's safest to do load free.

 

[telectrix]

r2 is nothing to do with the spur. it could be a poor connection anywhere on the ring. and please differentiate betweem r and R. it's confusing if you mix them up.

 

[tony mc]

Tel, could you explain the process of bypassing the RCD and MCB for the high current test. Would you just link the circuit line to the load side of the main switch temporarily? Anything to keep in mind for this - obviously I would say it's safest to do load free.

Bypassing the RCD/MCB


ISOLATE the circuit in question and double check that it is isolated!!


Link the CPC and Line at one of the socket outlets on the circuit in question


At the CU with your tester set to High ZS Loop place one probe on the outgoing side of the isolated circuit being tested and the other on the Line supply on the main switch.


Note reading on tester and REMOVE LINK BEFORE MAKING CIRCUIT LIVE AGAIN!!

Hope this makes sense!

 

[telectrix]

Tel, could you explain the process of bypassing the RCD and MCB for the high current test. Would you just link the circuit line to the load side of the main switch temporarily? Anything to keep in mind for this - obviously I would say it's safest to do load free.

just been posted .. #29. by tony mc. and richard burns has posted an excellent diagram of the procedure .