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Discuss How to test a circuits in steel conduit as the cpc in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. Harry John Heatherley
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    Harry John Heatherley EF Member

    Location:
    Leicester
    Good evening

    I am currently a training to become an electrician. I do hold both initial verification and periodic testing qualifications however this is an issue I have never personally had to deal with and was never mentioned on any of my courses as often seems to be the case.

    Basically I am wondering how you would hypothetically go about testing either a ring or radial circuit if you didn't have a seperate cpc but the conduit itself acted as this.

    Look forward to hopefully getting a response and some clarity

    Regards Harry
     
  2. TonyMitchell
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    TonyMitchell Electrician's Arms

    Location:
    Berkshire, UK
    Reg. 543.2.2 and 543.2.5. Treat it as you would any other CPC for testing.
     
  3. Harry John Heatherley
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    Harry John Heatherley EF Member

    Location:
    Leicester
    So with regards to the testing how would you gain and end to end reading for r2 and after that an R1+R2?. I understand I could opt for an R2 reading instead of R1 +R2
     
  4. TonyMitchell
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    TonyMitchell Electrician's Arms

    Location:
    Berkshire, UK
    You could either use a wander lead or link the conduit to the line conductor with croc clips (or banana plug to croc clip with an R2 adaptor) for R1+R2
     
  5. westward10
    Online

    westward10 In echoed steps I walk across an empty dream. Staff Member Moderator

    Location:
    Northamptonshire
    For a radial circuit you can calculate R2. If you measure the continuity of the line and neutral then divide in half this will give you R1 assuming the line and neutral are of the same length. Then measure R1 + R2 and deduct your first reading which should give you an approximate R2. For a ring final circuit you cannot do an r2 for the cpc as you have no end to end as such but you can use the same principle to to calculate R2 from the farthest point.
     
    • Disagree Disagree x 1
  6. anthonybragg
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    anthonybragg Electrician's Arms

    Location:
    NORTHAMPTON
    Business Name:
    CHARLTEC ELECTRICAL LTD
    R2 being the CPC I don't think you should be calculating it.
     
  7. westward10
    Online

    westward10 In echoed steps I walk across an empty dream. Staff Member Moderator

    Location:
    Northamptonshire
    There is nothing wrong with my suggestion, you are using various measurements and using some calculations to extract R2. Using a wander lead and subtracting the leads resistance is no different as this is also a calculation.
     
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    • Disagree Disagree x 1
  8. ipf
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    ipf Forum Mentor

    Wander lead and measure for R2. On the results, fill in R2 rather than r2 and R1+R2. On the schedule, 'cont' (containment) for cpc.
     
    • Agree Agree x 2
  9. Harry John Heatherley
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    Harry John Heatherley EF Member

    Location:
    Leicester
    Thanks for that much appreciated
     
  10. PEG
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    PEG Respected Member

    Location:
    Manchester
    Hi,and don't forget to do the inspection part,as,if containment is effectively,a CPC, with possibly dozens of "connections",it may pass the testing,but could give a visible indication,of not being capable of sustaining a higher,fault current.
     
    • Agree Agree x 2
    • Like Like x 1
  11. Gary Moore
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    Gary Moore 19 years in and not loving it

    Location:
    Walsall
    Business Name:
    On the books
    You should never calculate R1 +R2. Or R2 But you can calculate your ZS. This is what the NIC have told me is acceptable
     
    • Optimistic Optimistic x 1
  12. westward10
    Online

    westward10 In echoed steps I walk across an empty dream. Staff Member Moderator

    Location:
    Northamptonshire
    How do you measure R2 with no calculation. Your own method not how the NIC think it should be done.
     
  13. Ian1981
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    Ian1981 Forum Mentor

    Location:
    North east
    During the design stage it is very much acceptable to calculate R1+R2 and necessary in most of, if not all cases
     
    • Agree Agree x 2
  14. Gary Moore
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    Gary Moore 19 years in and not loving it

    Location:
    Walsall
    Business Name:
    On the books
    I’m not talking about the design stage. I’m talking about testing on site. We should be avoiding live testing whenever possible. And doing an R1+R2 test. Then calculate the ZS. Not always possible I know but the NIC I believe are trying to get this pushed forward because people are working live on steps trying to do a ZS and having accidents
     
    • Agree Agree x 1
  15. westward10
    Online

    westward10 In echoed steps I walk across an empty dream. Staff Member Moderator

    Location:
    Northamptonshire
    So how do you do an R2.
     
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