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  1. CDB
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    CDB Active EF Member

    Location:
    UK
    Hi,

    I was doing my r1+r2 tests on a lighting circuit yesterday in a 6 bed house over 3 floors. Approximately 20 points not including switches. Mainly pendants but some light bars etc and almost all LED or low energy halogen type bulbs. Closed circuit r1+r2 values range from 0.88 on ground floor to 3.06 on top floor.

    The lights all work ok. I believe I have found one pendant with a discontinuous earth not picked up on a recent EICR done by a 3rd party, which I will return to this week and fix.

    However, a couple of pendants were giving me values of over 130 ohms when the switch was open (light off), which I check as part of the polarity test.

    Can someone help me understand why these high r1+r2 values might be occurring?

    Thanks

    Chris

    IMG_4494.JPG
     
  2. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Have you carried out an insulation resistance test on the circuit?
     
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  3. CDB
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    CDB Active EF Member

    Location:
    UK
    Ah yes, good question. I should have said.

    I have performed a R1+Rn - R2 insulation test and got 130Mohm. Not perfect but acceptable. R1 - R2 has not been done as yet because I don't want to have to remove all the bulbs!
     
  4. DPG
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    DPG Electrician's Arms

    Location:
    S Yorkshire
    Are you confusing readings somewhere? You mention a continuity reading of 130R and an IR reading of 130M. Is it just coincidence you have similar results? (I know they're a factor of a thousand different, bu tyou know what I mean).
     
  5. Risteard
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    Risteard Electrician's Arms

    Location:
    Derry, Ireland
    Business Name:
    Walsh Electrical Services
    You're reading through the lamps back to the neutral bar.
     
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  6. CDB
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    CDB Active EF Member

    Location:
    UK
    No its just a coincidence. I've got two pendants its happening on. one is reading around the 130 mark and the other is at 150.
     
  7. CDB
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    CDB Active EF Member

    Location:
    UK
    Can you explain what you mean. Sorry.
     
  8. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Turn the switches on, why have you got them off. You have lost the R1 return at the light with the switch off.
     
  9. CDB
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    CDB Active EF Member

    Location:
    UK
    You misunderstand. This is for just one of the two problem pendants. With the switch closed/on I'm getting 2.89ohm but with the switch open I'm getting 150ohm when I would expect to see >2000ohm (open circuit) as I do for all of the other pendants.
     
  10. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Do you have all the lamps removed.
     
  11. CDB
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    CDB Active EF Member

    Location:
    UK
    Nope but I'm using the same method on another 18 pendants on the same circuit and getting open circuit when The switch is open/off. And many of them have the same model of bulb so why would these two be different?
     
  12. Pete999
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    Pete999 Trusted Advisor

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    Location:
    Northampton
    Do you mean R1+R2? r1 r2 and rn are for ring finals only
     
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  13. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    Its hard to follow your description of what is your situation but here 's a try

    The only thing you are removing when you switch off are the switch live back to the pendant and the switch contacts
    If you are now getting 130 ohms where 1000s were expected,it seems to me it can only be via the open switch
    Have you measured the switch itself as a separate item
     
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  14. static zap
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    static zap Regular EF Member

    Location:
    west midlands
    Comparing cold bulb and 130R ,just leaves heat damage ,
    causing tracking somewhere ,or another cause.
    Are the halogens 230V ,or is some 12V converter envolved .
     
  15. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Any 2 way lights in the mix?
     
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  16. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Are you doing an EICR or fault finding.
     
  17. CDB
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    CDB Active EF Member

    Location:
    UK
    Thanks for all the help guys.

    An EICR was done but NOT by me. This issue was not raised and neither was the discontinuous earth. The remedials listed were fixed and I have since changed the CU and am testing all the circuits I've moved for my EIC.

    There is two way on the hallway lights but not the ones affected. Screenshot below shows my readings.

    Thanks again.

    Capture.PNG
     
  18. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Are you registering voltage between line/earth at the light fitting and is the insulation resistance clear.
     
  19. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Is this 130 and 150 ohms or meg ohms.
     
  20. CDB
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    CDB Active EF Member

    Location:
    UK
    ohms for the switch on / closed for those particular circuits. 130Meg Ohm for the r1rn to r2 insulation resistance.
     
  21. CDB
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    CDB Active EF Member

    Location:
    UK
    Obviously this is a dead test so if you are asking about 230v I have not looked.

    But could I be picking up on Smoke/Heat alarms or Emergency Lighting?

    But if that is the case then why are the other lights not seeing the same issue. Argh - my computer scientist brain likes consistency!

    Thanks for the continued help by the way!
     
  22. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    It isn't a problem I thought you meant ohms for when the switch was open. I assume you get 130 meg ohm when you IR test the whole circuit with all switches closed.
     
  23. CDB
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    CDB Active EF Member

    Location:
    UK
    Yes 130 meg ohm for IR.

    But either 130 or 150 ohm for the two problem pendants when switch is closed.
     
  24. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    It is not a problem 130 meg ohm is well above what you require. Your picture indicates the wiring to be 50 odd years old and you would not necessarily expect an infinite IR reading especially on a lighting circuit, I would think no more of it.
     
  25. CDB
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    CDB Active EF Member

    Location:
    UK
    It's not the IR that concerns me because as you put it the wiring is old and it's well above the minimum.

    My question relates to the 130 OHM and 150 OHM I'm getting for the R1+R2 test on two different pendants when the switch is open. If the switch is open I should be getting open circuit or in my case >2000 ohm as I do with all the other lights on that circuit.
     
  26. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Are the switches relatively old as you could be getting dirt on the contacts at the switch tracking across or you may have leakage through lower insulation resistance
     
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  27. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    It is possible old, worn switches are the cause but I wouldn't have thought low ohms would pick this up but yes ditch the wiring from the switch.
     
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  28. Ian1981
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    Ian1981 Electrician's Arms

    Location:
    North east
    Disconnect at switches and see what you get
     
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  29. CDB
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    CDB Active EF Member

    Location:
    UK
    Hi Ian,

    Dodgy switches was my first thought. They are old.

    To determine your second suggestion I guess I would need to do a full IR which is pretty difficult given the installation.

    Switches first!

    Thanks for the ideas.
     
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  30. spinlondon
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    spinlondon Trusted Advisor

    Location:
    Harlow Essex
    Are the CPCs for these pendants connected in terminals, or twisted together either at the roses or perhaps in JBs in the loft?
     
  31. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    Why is it difficult to do a full IR you can ignore the L/N test.
     
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