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Multicore cables (YY but not PVC/PVC)

jbrameld
I wonder if I could previal for some learned opinions.


We undertake installations of stage lighting amongst other things, and often use a 19-core 'YY' type cable (though it isn't really YY as the insualtion and sheathing is not PVC/PVC - it is a LSF variant) for links between switched power units or dimmers and internally wired lighting bars.


We have undertaken many such installations, and we are registered with the NICEIC who have audited and inspeced many such installations and passed them.  We have also raised specific questions with them on the use of the cable and we get varying answers.  They are never willing to give an emphatic 'yes', but neither do they say 'no'.


As I understand it - there is not a relevant construction standard that covers this type of cable construction, so it can't comply with a standard that doesn't exist.  There are however many standards (many of which form normative references for construction standards of other cable types) with which it does conform.  These include EN 50525-1 (General requirements) EN 60228 (conductors) and various fire performance standards (EN 50575, EN 60754, EN 60134 and EN 60332).  We also know that the insualtion and sheathing material is standards-compliant and is commonly used in cable manufature.


We are embroiled in a dispute with a main contractor who is claiming the installation is non-compliant as the cable does not meet a construction standard. Reg 511.2 allows for use of euipment not covered by a Britsh or Harmonised standard if the designer/specifier confirms that the equipment provides at least the same degree of safety.  This cable is covered by multiple standards but not a single 'construction' standard that is applicable to this type


We have undertaken what we believe to be a thorough assessment of this cable which is attached here:  Assessment of Cable NILTOX LF 319.docx


The use of the cable is noted on the certificate and the assessment and supporting documentation from the supplier is attached, but the main contractor is still refusing to accept this route.


So a couple of questions for the learned community:
  1. Have we missed anything in our assessment, or does it seem thorough and complete?

  • Should the use of this cable be recorded as a 'departure' (our agument is that we have complied with 511.2 and therefore it is not a departure) or just recorded as a note?


Thanks in advance.  Happy to answer any further questions.


Jason.
  • 0
    Well that is a pretty thorough 'deep dive' into the cables capability,  so well done on that degree of rigour, it is rare.

    As described, I see no problem with the cable technically given the standard tests performed on it.

    I'm assuming of course that the cable is routed, supported and protected from sharp edges and impact in suitable ways, given it is a sort of flex.


    A question in two parts,


    1) what aspect of the cable performance is cause for concern ? (other than paperwork)


    2) Who is signing the 'designer' part of the installation cert. ?


    Is the real problem that the contractor does not want to adopt responsibility for something he/she  has not designed personally?

    Who is contracted to who ? It may be better that you sign as designer, and them as installers and testers, if the plans are your creation.


    The other aspect is who is answerable to whom,  are the contractors working for you, or for the outfit that owns the building ?

    Mike.

  • 0
    Thanks Mike.


    To answer your queries - we are sub-contracted to a main contractor, who is building a new school for the DfE.


    We are signing all elements of the certificate - design, installation, testing.  We believe all the responsibility is ours as a result.


    There is one particularly beligerent, blinkered and pedantic individual at the main contractor who is citing that it is a non-compliant cable as it is not to a British or Harmonised construction standard or BASEC approved (not that third party approval is a requirement).  He is also claiming that as we are not qualified cable designers we are unable to make an assessment of equivalent safety.  He also claims that the methods, tables and calculations etc. in BS7671 only apply to cables meeting relevant standards.


    I would argue that we are able to make a reasoned assessment based on the manufacturer-provided information, and that as every aspect of the cable  that we have examined is in accordance with the listed Standards (conductors, insualtion/sheathing materials, fire performance etc.) that the BS7671 information can be applied and the cable is safe.  From a calcualtions perspective we're not even close to the margins.  There just isn't a relevant overall standard for this type of cable.


    The cable is mechanically protected in either trunking or flexible conduit where below ceiling level, and is installed on a cable basket in the ceiling void.


    Thanks,


    Jason.




  • 0
    This is basically a contractual dispute, and its resolution in part will boil down to what your contractual obligations are, e.g. whether all work "is to BS7671:2018" or whatever.
  • 0
    Wally - Yes - you are correct, and we are required to provide an instalaltion in accordance with BS7671:2018 - the views I am seeking here as to if we have done that (in respect of this cable).
  • 0
    The NILTOX LF319 cable meets several B.S. standards. Is that not good enough for the man?

    Microsoft Word - Niltox LF 319 Number Coded Class Dca s2, d2, a1.docx (fscables.co


    Extract from seller's website.


    "Developed to meet the need for Low Smoke Halogen Free flexible control cables, the NiltoxRegistered LF-319 range of LSHF YY control cables covers all the popular sizes with cores number coded. Applications include airports, hospitals, lift shafts, tunnels, heating and ventilating controls, in fact anywhere that conventional PVC YY cables are used."




    Z.


  • 0
    Appaently not - sadly........We have tried that argument and sent that data sheet (and more detailed QA and test data from the manufacturer) but according to him, none of those are a 'construction standard'.


    Jason.
  • 0
    I have a lot of experience in this area. I have a couple of questions that may allow you to silence him.


    You have used 18 core cables, have you used connectors on the ends, ie socapex or similar?

    Where do the cables run exactly, are they from dimmers to fixtures for example, and are they enclosed in trunking or other containment, or can they be moved?

    If any are fixed and in containment, what is his objection because they are just multicore versions of other XLPE cables or singles you could have used?

    This is basically an 18 core yy cable, presumably to the YY EN standard, it does not need a BS number or anything else in BS7671.

    Can he suggest another cable that does have a standard with which he is satisfied?

    Are flexible cables need for the job, or was this convenient to you as the contractor?

    Has the contract insisted you use LSZH cables?

    Regards

    David CEng etc

  • 0
    davezawadi (David Stone):


    This is basically an 18 core yy cable, presumably to the YY EN standard, it does not need a BS number or anything else in BS7671.


     


    David, that's the problem ... at the moment, there is no constructional EN standard for YY (or CY or SY) cables. I understand one is being developed at the moment. In any case, the "Y" means PVC so I guess this would be a non-standard cable anyway?


    See section 7.9 of the On-Site Guide (page 90 in the 2018 Edition).



    To the Original Poster, the last two paragraphs of Section 7.9 of the On-Site Guide tells you what is necessary for BS 7671 compliance, where YY, CY or SY of other non-standard cables have to be used (and there are sometimes very good reasons for doing so - however, for SY/CY/YY and similar cables, those reasons do not include "mechanical protection"). If your cable meets those requirements, and you've selected the correct types (note that some of these cables are only suitable for use as auxiliary cables, not power cables) then provide the relevant evidence to your Client, along with the OSG (Section 7.9) as reference.


  • 0
    jbrameld:

    Appaently not - sadly........We have tried that argument and sent that data sheet (and more detailed QA and test data from the manufacturer) but according to him, none of those are a 'construction standard'.


    Jason.


    As per my previous post, OSG tells you what is needed. Provide that information and use the OSG as a reference. If you don't have the information and confirmations stated in the OSG, then perhaps the main contractor is correct in this particular instance?


  • 0
    I would have to say it was a departure from BS7671.

    Looking at 133.1.3, which has almost identical wording to that in 511, it says the uses should be recorded in the appropriate certification in Part 6. This would be an EIC on page 462 where the Design departures box includes reference to 133.1.3 (no mention of 511)

    so as a departure I assume it wouldn't fully comply with your contractural agreement I'm afraid


    also typo in your attachment ; LVD AC voltages from 50 to 1000V not 100V

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