r1 + r2 testing

[Richie Fox]

You know when you are at the last socket or outlet on a radial circuits as it will have the highest resitance reading and yes and single cable feeding it is a good indicator but beware as that may also be a radial off of a radial.

 

[ockey]

thanks 4 al yr help, im just leaningl,but u no what i ment ?????????? r1+r2 (R1+R2)

 

[ezzzekiel]

Hi.

Do you mean R1+R2 test or, the r1 and r2 tests??

pet hate of mine, but well explained my mr len

it can be difficult to accurately find last point in a circuit - as you move further down the circ the higher the reading , but more often than not you can guess which logical route to follow

 

[Monks]

I'm just bumping this thread as I have a similar question: Is there such a thing as an R2 reading? I've just been looking at one of the test sheets given out at college similar to the one that I will be using tomorrow in my Level 3 practical exam and it asks for an R2 reading as opposed to r2 (without caps). Is it just a typo, or am I missing something? Also, in the continuity part of the sheet next to it is a column for R1+R2 and a small column that says 'Ring'. I don't understand why the 'Ring' box is there; what is it asking for? There are no columns for r1, rn, or R1+RN.

Any help would be much appreciated. Thanks.

 

[Martin Bradley]

Good book to get for learners is Alan Lynch the part p Doctor.

 

[malcolmsanford]

R2 is Test method 2 it is used to find the continuity of both earthing and bonding conductors.

In the case of Main Equipotential bonding you would disconnect the, say water bond from your MET and croc clip it, then with at the pipe you would clip the pipe, as that is my way to ensure your BS 951 clamp is secure and do your reading, using a low resistance ohmeter

In the case of what your looking at on a distribution or final circuit, you would clip a wander lead onto you CU earth bar and at each point in the circuit you would take a reading of the CPC, with your low resistance ohmeter.The highest reading would be your R2 reading which you would put into that column. If this method is done then there is no need to do the R1+R2 test, though the majority of electricians prefer this test to the R2 one

The ring box is a tick. It would be checked off if the socket outlets in the installation was wired in a ring final circuit, if the sockets were wired in a radial then it is left unchecked.

 

[Monks]

Thanks for taking the time to write an in-depth response, Malcolm. Reading your reply has just jogged my memory and the continuity for the ring part of the sheet makes sense again now. I knew I was missing something as it made sense last week. Thanks again.

This forum is a fantastic resource. Cheers.

 

[tomma]

Little r1, rn, and r2 are end to end resistance measurements, of line, neutral and earth on a ring final circuit. Cross connecting r1 and r2 then taking a measurement of these in parallel, equals Big R1 + R2.

 

[telectrix]

ok cheers, bare with me with this, on a radial circuit in a house, how would you know which is the last socket?
thanks for your help

on a radial, the last socket is the one with only 1 cable in it.

 

[ezzzekiel]

On any circuit the last testing point is the one hidden in the smallest darkest place with mountains of rubbish on top

 

[martinh89]

Little r1, rn, and r2 are end to end resistance measurements, of line, neutral and earth on a ring final circuit. Cross connecting r1 and r2 then taking a measurement of these in parallel, equals Big R1 + R2.

from what ive been shown line end to end is R1, cpc end to end is R2 and neutral end to end is Rn.
The values of R1,R2 and Rn will indicate whether or not the conductors are continuous.
Once you cross connect the conductors to create a parallel circuit thats when they become r1 r2 rn

 

[tomma]

What you should have been shown is line end to end is r1, cpc end to end is r2 and neutral end to end is rn.
The values of r1,r2 and rn will indicate whether or not the conductors are continuous.
Once you cross connect the conductors to create a parallel circuit that's when they become R1+R2 This is documented on the initial Inspection and Testing report

 

[spencerwalters]

R1+R2 testing please

thanks for you information mate

 

[bf03yvd]

R1 is R2D2's pal.

 

[Pete999]

OP have not got a copy of the OSG? r1 r2 and rn, as well as R1+R2 is explained in some detail, as is the explanation in GN3