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7 STRAND TAILS V 19 STRAND

I changed a consumer unit  a week ago and for the first time used 19 strand tails instead of 7 strand tails. I have to say they are much easier to use and manipulate in tight spaces. I think they are a much better for terminating in a cage clamp as they fill the space under the cage making more contact than 7 strand.


I purchased them from Tool Station and found they were made by Doncaster cables. A bit more expensive than 7 strand but worth the extra money. 


  • John, I found those too by chance a couple of weeks ago when looking through the catalogue for something else.

    I agree they were really nice to use and the cost difference was small so will use those again.

    On that visit also by chance found 3-pole inline lever connectors (l-n-e straight through) which are quite compact so a useful visit considering I didn’t go in for either!
  • Ah, but does your local DNO/supplier approve them for use in their supply terminals?

       - Andy.
  • Could always stick 100 amp blocks in line, or even an isolator, I might actually do that on my last job, the tails are pushing the CU isolator out of kilter
  • I have no idea Andy. UKPN  will not allow Tri Rated if they are presented with them for connection to heads or transformers. I cannot see why they could not be terminated in a meter with tunnel terminals? Just  a different method of preparing the ends, for cage clamps take out the manufacturers 1/2 twist and flatten the copper to make a spade shape that touches all 4 sides of the cage clamp. For tunnel terminals consolidate the ends by putting an additional twist in to the manufacturers 1/2 twist. If you are really old school wrap a 1mm copper binding wire over the consolidated ends. 


    In my case my ends went in to single pole Henley blocks (AKA service connectors) and the cap screws tightened with my nice new Boddingtons T 3mm insulated key, my installation so nothing to do with the DNO or meter operator. Nice tight fit and plenty of contact area and 2 screws to secure the copper. The Boddingtons T key is the same one as the DNOs use for heads, Henleys and meters which I purchased at an Elex show last year. If you do not have one and terminate tails on a regular basis I would recommend you get one!
  • Love the chairs....https://www.youtube.com/watch?v=kKxbDo6j_B8

  • AJJewsbury:

    Ah, but does your local DNO/supplier approve them for use in their supply terminals?

       - Andy.




    Do the terminals themselves (supply end of consumer unit end) support connection of conductors without suitable preparation (e.g. ferrule), re Regulation 526.9.1 ?


    There are 4 classes of conductor currenty in use for installation cables, although there used to be more (hence the numbering):


    Class 1 - solid (although larger csa conductors are obviously not a single solid strand, there may be 5, 7 or more).

    Class 2 - stranded (typically, minimum of 7 strands for all csa)

    Class 5 - flexible (sometimes called finely stranded)

    Class 6 - extra-flexible


    Most fixed wiring terminals are suitable for Class 1 solid, and Class 2 stranded, conductors without preparation, and Class 5 and Class 6 requiring ferrules (the exception being connection units to BS 1363 which are suitable for connection, at least on the outgoing terminals, of Class 5).


    Worth checking.what you have, and what the terminals are designed for.

  • Would you adjust the CCC i.a.w. Appendix 4 para. 2.4? It might only matter if you have a 100 A supply and the tails are in trunking, etc. (Table 4D1A)

  • Blencathra:

    Love the chairs....https://www.youtube.com/watch?v=kKxbDo6j_B8




    Well designed chairs, very novel.


    Should the yellow SRG1VCU surge arrestor be at the far end of the consumer unit or next to the main switch?


    Z.

  • Former Community Member
    0 Former Community Member
    The thing is if you look at the standards and the definitions of the conductor classes, 19 strand does not meet Class 5 or 6, it is also not Class 2, so it must be a carry over from classes 3 or 4...

  • The Doncaster Cables Data sheet says that their 6181Y cables including the 19 strand 25mm2 cables are either class 1 or 2.  As the smaller sizes are single strand the rest according to Doncaster are Class 2.  "Plain Annealed Copper Class 1 or 2 to BS EN 60228 "

    The data sheet is a bit awkward to find  http://www.doncastercables.com/uploads/6181Y_Datasheet.pdf 

    Its described as a National Type.  Does this give them some wiggle room.  OFC no one would quibble with the termination of a 6mm2 6181Y cable in a consumer unit.  This has 7 strands of small diameter than the 19 strand 25mm2 - perhaps there is a clue here.

    I have used this cable too and I agree its much easier to use than the 7 strand.  I did ask Wylex about it but am still awaiting a response.....