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Discuss wiring a ring in 2.5 is no longer acceptable? in the Electrical Wiring, Theories and Regulations area at ElectrciansForums.co.uk.

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  1. willelec
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    willelec EF Member

    Location:
    England
    So my boss had the NIC inspector out the other day and he mentioned that wiring a ring in 2.5 is no longer acceptable. He stated that even wiring a ring in 4mm is now pushing it when it's installed in insulation.

    We have always wired rings in 4mm as we wire large holiday homes. All my other sparky mates use 2.5..

    I'm just wondering if anyone else has had this said to them and if it's just the NIC being really picky as usual.
     
  2. Vortigern
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    Vortigern Electrician's Arms

    Location:
    England
    Business Name:
    F.H. Electrical
    So I suppose we should use 6mm² instead then. So even if calcs show it is ok, then it's not according to NICEIC. Lets get rid of BS7671 then and just phone NIC to see what we should do in every circumstance. A shame that a ring circuit is no longer "deemed to satisfy" (NIC)
     
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  3. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Hi Will. and welcome to the forum !
    Maybe they are talking about the effect of insulation? The cable for a 32A ring must have a rating of at least 20A and for cable floating loose in a cavity wall with insulation the 2.5mm is only 13.5A (Table 4D5, method 103). Even 4mm is only 17.5A. So either 2.5 or 4mm can work for a ring, but insulation can spoil it ...
     
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  4. PEG
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    PEG Trusted Advisor

    Location:
    Manchester
    Hi,wiring a ring final circuit,in 2.5 is perfectly acceptable.

    Applying other factors,to that circuit,such as external influences,grouping,temperature,etc,is also acceptable.

    Taking the two statements,separately,is not acceptable.

    I hope NICCY,find my explanation...acceptable ;)
     
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  5. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    If the NICEIC want to make sweeping statements they need to back them up with facts from BS 7671
     
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  6. Pat H
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    Pat H Don't ask, get an Electrician in.

    Location:
    Ware Herts
    Business Name:
    Sparks of Intelligence
    Surely it depends on the installation method and the rating of the MCB?
    Nowadays ring mains often aren't required to carry 32A so if on a 20A breaker or even a 16A then 2.5mm maybe ok.
    Its all down to the calculations.
    I've just done a ring main for a loft conversion but was able to minimise the cabling contact with insulation. So it was largely surface mount in free air. But if it has to go in wall and be completely insulated then it depends on the calcs and the current required.
     
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  7. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    I suspect there are some crossed wires here with regards as to what the inspector said.
     
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  8. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Are they 2.5 mm or 4 mm?
     
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  9. Pat H
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    Pat H Don't ask, get an Electrician in.

    Location:
    Ware Herts
    Business Name:
    Sparks of Intelligence
    Harmonised or not wires?
     
  10. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    I'm waiting for the 18th where 802.11 is included, I heard ...
     
  11. hightower
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    hightower Electrician's Arms

    Location:
    Durham
    Oooo, don't let @Pete999@Pete999 hear you call it that.
     
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  12. Chr!s
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    Chr!s Electrician's Arms

    Hi, well is insulation is involved then yes he's right, it derate's the cable.
     
  13. Andy78
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    Andy78 Trusted Advisor

    Location:
    Kingston upon Hull
    Plenty of ways to avoid this problem through proper design rather than making up blanket rules for numpties who don't ever do a single cable calc.
     
  14. Pat H
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    Pat H Don't ask, get an Electrician in.

    Location:
    Ware Herts
    Business Name:
    Sparks of Intelligence
    I've got fed up calling it a RFC and customers asking whats that. Easier to call it a ring main and they know what I mean.
     
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  15. 7029 dave
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    7029 dave Trusted Advisor

    Location:
    bedfordshire
    I would love to see anybody fighting anything more than 4mmx2 into the back of a socket. lol
     
  16. spinlondon
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    spinlondon Trusted Advisor

    Location:
    Harlow Essex
    Then add a spur.
     
  17. 7029 dave
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    7029 dave Trusted Advisor

    Location:
    bedfordshire
    Yes, no bloody chance.
     
  18. hightower
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    hightower Electrician's Arms

    Location:
    Durham
    Just cut a few strands out
     
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  19. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    @ HT. go directly to the plumbers forum do not pass GO. do not collect £200.
     
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  20. Pete999
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    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    HT wash your mouth out with carbolic soap, then spend the rest of the day on the naughty step, you bad Boy:rage::rolleyes:
     
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  21. Last plumber
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    Last plumber Electrician's Arms

    Location:
    Lancashire
    CHEEKY !
     
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  22. streamer
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    streamer Regular EF Member

    Location:
    Scottish Borders
    I always thought it was okay to cut a few strands out as long as you made sure it was the same strands at both ends of the cable.
     
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  23. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    I too don't see a problem the cable only needs increased csa through the insulation not at the accessories so you could cut it back to 2.5:D
     
  24. Pete999
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    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    OK how many strand from a 4mm to convert it to 2.5mm?
     
  25. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    I reckon each strand is 0.57mm so you would have to remove two and get a bit of wet and dry on a third one:p
     
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  26. pdbeare
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    pdbeare New EF Member

    Location:
    llandudno
    Insulation is becomming a big factor these days with new builds slapping it in everywhere 200mm minimum in lofts!! Ridiculous!
     
  27. Sparkingmad
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    Sparkingmad EF Member

    Location:
    Dorset
    6mm for cookers / hobs will now have to be 10mm if they keep insisting on stuffing fibreglass in between floor joists because the builders won't pay the extra for other insulation material. Then imagine trying to get 16mm into shower switches.
     
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