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Discuss R1 + R2 of ring circuit in the Electrical Forum area at ElectriciansForums.co.uk.

  1. haptism

    haptism Regular EF Member

    Location:
    SW. London
    Hi for a ring circuit, is there any need to measure and enter R1 + R2 values on a schedule of results ? Because an r2 value is already measured (together with r1 and rn). If I needed a ring R1 + R2 value to calculate ZS (although i would find ZS with a socket tester so really no need; but if I did) would i find it using the formula ZS = (r1 + r2)/4 ? Thanks all
     
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  3. Hellmooth

    Hellmooth Electrician's Arms

    Location:
    Livingston
    Business Name:
    CM Electrical
    Verification that it is a ring circuit would be a good reason.
     
    hightower and Pete999 like this.
  4. jackhammerJIM

    jackhammerJIM Regular EF Member

    Location:
    north yorks
    That would be r1 rn r2 . not R1 + R2

    R1 + R2 IS required to confirm polarity
     
  5. Wilko

    Wilko Gorillas are Great Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Yep, values from testing are needed for your test schedule for both r and R. GN3 has method laid out in section 2.2.6.
     
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  7. haptism

    haptism Regular EF Member

    Location:
    SW. London
    I dont have GN3 yet unfortunately. On the test schedule (IEE model form) there is a column for r1, r2, and rn values, so its obviously a ring im testing. The next column along asks for either R1 + R2, or R2; R2 is long lead method which would give exactly the same value as r2. So with that in mind whats the point of recording an R1 + R2, or R2 value if you have already measured r2 ?? Which my question is, do I need to enter an R1 + R2 value if i already have r2 ?? If you get what I mean that would be great ;)
     
  8. jackhammerJIM

    jackhammerJIM Regular EF Member

    Location:
    north yorks
    yes you need R1 +R2 to confirm polarity
     
  9. telectrix

    telectrix Appreciated Member Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    R2 reading wound not be same as r2.
     
  10. Wilko

    Wilko Gorillas are Great Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Def recommend GN3 ... I do tests and enter values for r1, rn, r2 and (R1+R2). Then I compare (r1+r2) to (R1+R2), looking for the magic 4 factor if I've built it right :)
     
    Last edited: Jan 11, 2017
  11. kropaske

    kropaske Active EF Member

    Location:
    Feltham
    With r1 r2 rn you confirm that it is RFC by doing R1+R2 you verifying that cpc is actually connected to the socket and as jackhammer said verifying polarity
     
  12. sparksburnout

    sparksburnout Electrician's Arms

    Location:
    Notts
    Or an I&T course? Like a sparks....
     
    Pete999 and Risteard like this.
  13. Risteard

    Risteard Electrician's Arms

    Location:
    Derry, Ireland
    Business Name:
    Walsh Electrical Services
    It certainly shouldn't if done correctly! In fact it should be a quarter of the r2 value if there are no spurs. But given that the test for the (R1+R2) value is required as part of the ring final circuit continuity tests I see no merit in opting for R2 over (R1+R2) presuming that we are discussing initial verification here.
     
  14. haptism

    haptism Regular EF Member

    Location:
    SW. London
    Okay, so in step 3 of the ring final test, when you cross connect L + E, the highest result is your R1 +R2. Having a brain drain today, quickly why would R2 differ from r2 ?
     
  15. kropaske

    kropaske Active EF Member

    Location:
    Feltham
    correct

    r2 is end to end
    R2 is when joined together
     
  16. haptism

    haptism Regular EF Member

    Location:
    SW. London
    Thanks all, and thanks for your patience and goodwill,
     
    DPG likes this.
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