R2

[Ross Trician]

hello all, just after some info please. Can someone explain/clrify what on a shedule of test results is required for R2.

I understand r1+r2 but what is needed for just r2?

 

[wayne]

when testing you can actually get away with only knowing the value of the cpc(r2)this is "the long lead method "
however by doing it r1 &r2 you get to check polarity also
im posting this off top of my head so im sure someone will clarify further

 

[mdavismccoy]

Just a note, an example:

Lighting circuit, at the furthest point, last one on the circuit. Join the L & N together, take a resistance reading, R1 and N, half the result, you get R1.

Then join the L and CPC together, take a resistance reading, R1 +R2. One of the readings reqiured. Now subtract R1 from the first test above, you are left with R2.

The same way to get the R2 of a ring. The reistance of R1 and N, in the figure of 8, half the result. Then L and CPC, R1 and R2.

 

[mdavismccoy]

A note for the above, is for T&E cable where the cpc is smaller.

Where the L and the CPC are the same size, do the above and just half it.

 

[Shakey]

Just a note, an example:

Lighting circuit, at the furthest point, last one on the circuit. Join the L & N together, take a resistance reading, R1 and N, half the result, you get R1.

Then join the L and CPC together, take a resistance reading, R1 +R2. One of the readings reqiured. Now subtract R1 from the first test above, you are left with R2.

The same way to get the R2 of a ring. The reistance of R1 and N, in the figure of 8, half the result. Then L and CPC, R1 and R2.

????????

mate, where the hell did all that come from?

Firstly the R1+R2 for the lights is not neccassrily the last one on the circuit, it is more likely to be the one with the two way switching, which is why we link phase and CPC at the board, measure R1+R2 (switched phase to CPC )at each and record the higest value

thats it R1 +R2 for the lights. Neutrals got nowt to do with it


You could possibly make it more complicated than you have done, but I can think how!!!

In answer to the original question

You are required to confirm the continuity of the protective conductor

you may do this as I have just said, which is convenient because you can ad it to your Ze to get a Zs value and avoid breaking the EAWR's

the R2 method is an alternative (not an additonal) check carried out, as said, by running a long fly-lead out and measuring the resistance of the CPC (R2) at relevant points in the circuit.

You are required to establish (R1+R2) OR R2, not neccassrily both


Mdavis, I got a few spaces left on my next 2391 course, or maybe you would be better starting with the 2392

only joking!

 

[mdavismccoy]

The original question was :- Can someone explain/clrify what on a shedule of test results is required for R2.


I have explained how to get R2 with out a long lead. The schedule of test results ask for R1 + R2 or R2. The Highest reading recorded. If You Have wired a circuit you know which is the furthest fitting. With the two way you need to activate the switches record the highest reading.

The Neutral is used for resistance measurement only, instead of a long lead. It would take a lot longer to set up a long lead to the furthest point, say last light in the loft, easier and quicker to use the neutral. I know that you only need R1 + R2 or R2.

You may use a long lead for measurement of the bonding.

I Have C&G 2391 and C&G 2382 thank you.

 

[mdavismccoy]

Sorry chaps. I went of in a tangent. No excuse.

But if I did have, it would have been my gold fish got run over, that was assuming I had a gold fish.

 

[Shakey]

Sorry chaps. I went of in a tangent. No excuse.

But if I did have, it would have been my gold fish got run over, that was assuming I had a gold fish.

Hey no probs, what is the goldfish all about though