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Multicore cables (YY but not PVC/PVC)

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.
Parents
  • 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.


Reply
  • 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.


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