End to end testing on cpcs ring circuit.

[schoe]

Just a quick question I was testing my ring circuit the other day from the first socket off the consumer unit testing the end to end results of the cpc's. The first result I got was lowest, then when I went around all the sockets in sequence they got higher. The highest result was when I did the end to end in the consumer unit.

Is this correct or when you do the end to end results from a socket on the cpc's should they be the same as when you do it at the consumer unit?


Thanks chris.

 

[danzor]

Should be the same, did you zero the leads

 

[Deleted member 26818]

No it's not correct, they should be substantially the same.
Sounds like you haven't connected the conductors together correctly.
If you hold the cables one in each hand, you connect the left hand CPC to the right hand line, and the right hand CPC to the left hand CPC.
The values you have measured, would be expected on a radial rather than a RFC.

 

[Engineer54]

Think about what your testing and how. Think about distances from wherever your testing from and to where!! That should tell you the answer to your question....

 

[steve-the-hat]

I know it's probably a silly question, but was the battery running down in your tester?

I had a similar thing happen to me with some cpc readings and that was down to the battery.

 

[schoe]

Yeah zeroed the leads

 

[schoe]

What can this mean then?

 

[telectrix]

you can only test r1,r2,rN end to end at the ends of the circuit. i.e. in the CU. when you cross connect the line/cpc's at the CU, you are then measuring R1+R2, readings should be substantially the same ast each socket outlet, except if you have a spur, which will give a higher reading.

 

[schoe]

Think about what your testing and how. Think about distances from wherever your testing from and to where!! That should tell you the answer to your question....

I'm starting to worry now could it be to an interconnection , although my live and netural connections are both fine?

 

[schoe]

I originally did my end to end tests in the consumer unit and got these results,

L-l 0.93
N-n 0.90
E-e 1.46

I just changed a socket the other day so I thought I'd just check the end to end results, the socket change was the second one on the ring and I got 0.45 I think then it started to rise until I did the end to end in the consumer unit and I got my 1.46 result again.

I'm confused now, have I wired it up in correctly?

 

[Deleted member 26818]

I recently came across an installation, which had a RFC which consisted of just one socket-outlet.
All the other socket-outlets were spured off of this RFC, in I assume a spider arrangement.
Such a scenario would have similar results to what you describe, except for the measurement at the CU.
As I said before, the results you have obtained, suggest a Radial rather than a RFC.

 

[schoe]

So am I'm beIng stupid, defiantly wouldnt be the first time, can the end to end test on the cpc's on a ring circuit only be carried out in the consumer unit?

 

[Specialist]

No it's not correct, they should be substantially the same.
Sounds like you haven't connected the conductors together correctly.
If you hold the cables one in each hand, you connect the left hand CPC to the right hand line, and the right hand CPC to the left hand CPC.
The values you have measured, would be expected on a radial rather than a RFC.

Surely that gives you r1 / r2 not end to end of the CPC ?

 

[Deleted member 26818]

It is normal to just measure the end to end at the CU. Although there is no reason why you can't measure the end to end at each accessory.
You would however expect each measurement to be the same.
From what you have described, it sounds as if you are not measuring end to end at each accessory, but between different conductors at each accessory.

 

[1shortcircuit]

Could you confirm exactly what you did please?:thumbsup

Are you just testing the CPC or have you interconnected with a Line or Neutral?