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Part E

Chris Pearson
Yes, that's part E, not L, M, or P! ?


Scenario is studding wall between a landing and a bathroom. I don't suppose that anybody in the bathroom will be perturbed by noises on the landing, but one doesn't necessarily want to hear various splashings.


So we have a 2nd floor ring final coming and going in the wall along with the lighting circuit. 


I may be a bit thick, but I don't find the Part E Approved Document easy to interpret. If any wadding is to be put into the wall, then we potentially end up with Reference Method A, in which case the 2.5 mm2 cable is downgraded to 20 A. At this stage I want to ignore the possibility that two legs of a ring should be derated due to grouping.


My feeling is that the requirements of Part E can be met without recourse to wadding, but what I would like to know is whether any of you have encountered this problem, and if so, how you have addressed it. Many thanks. ?
  • 0
    2 x 16 = 32


    with a bit less 2.5 mm twin and earth cable than a ring.


    Andy Betteridge
  • 0

    AJJewsbury:




    If any wadding is to be put into the wall, then we potentially end up with Reference Method A, in which case the 2.5 mm2 cable is downgraded to 20 A.



    So what's the problem? - since the regs changed a few(*) years back so that we only need to meet a 20A requirement for ring cables, rather than 0.67x In, can't you have a compliant installation even with thermal insulation within the stud walls?


    I didn't even mention method 103#, but in answer to my original question, it appears that the consensus is "no problem", which is reassuring. Thank you.

  • 0

    If you run 16-amp radials in 2.5 mm twin and earth it alleviates all sorts of issues, such as lots of insulation.


    2 x 16 = 32


    with a bit less 2.5 mm twin and earth cable than a ring.



    But two 16A radials, although giving the same theoretical capacity, is a lot less flexible in practice. You can have three 10A loads on a ring without problem, but you can't on two 16A radials without overloading one of them (and having unused capacity on the other).


       - Andy.
  • 0
    That reduction in load diversity is reflected in the older recommendations about served floor area, and is why a 30A cct can serve more than twice the area of a 15A one.

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