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Orange Alu Split Con

Martyn
Hi All, 


As per the title I need a 25m ish length of 25mm Orange Alu split con, cant seem to get it from the cable suppliers unless I order to be manufactured with crazy minimum order quantities.


Cant use standard Split con as it’s PVC and I need LSF for an escape route, cable forming part of a BNO replacing a degraded cotton service.


It’s only manufactured in 25 & 35mm apparently, could use either but prefer 25mm.


Anyone with a short length?


Cheers


Martyn
  • 0
    e1621be504b780ede5ff1c1e776721bb-huge-img_20190916_213955.jpg

    The boundary is clear, at the outgoing terminals of the intake. "Wiring Regulations" from there. Regards, UKPN
  • Former Community Member
    0 Former Community Member
    but a building network, by definition, isn't a consumer's installation.


    Where is this defined Andy?


    Regards


    BOD
  • 0
    UKPN...


    The cable is as per your picture SNE ?


    Bod


    I have no intention to be burying any SNE cables to the point where they need such protection; it’s basically T&E as far as protection is required. Method not set in stone yet but either on tray or clipped direct to the finished surface, providing suitable clips can be found! The rubber lined metallic P Clips look decent but quite labour intensive! Either way it’s not going to look good in the communal areas!
  • Former Community Member
    0 Former Community Member
    I'll try again with the neutral insulation by cutting and pasting, so apologies if it doesn't copy well. Note the final comment............... Regards. BOD

     
    31 July 2007 09:55 AM
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    briandoherty


    Posts: 313

    Joined: 08 May 2004

     

    Mr P,


    I apologise in advance for the length of this post!


    I got the colour wrong in my previous "second-hand" quote regarding BS4553 (split concentric cables) ( I said "blue" instead of "black")!


    However, now I'm back in the office, I can confirm the actual wording in the standard is as follows (underline emphasis is mine):


    "BS4553-1:1998 Specification for 600 / 1 000 V single-phase split concentric electric cables - Part 1: Cables having PVC insulation...


    1 Scope

    This British Standard specifies requirements for construction and gives methods of test for PVC-insulated single-phase split concentric cables for operation on an earthed neutral system at nominal voltages up to and including 1 000 V between phases and 600 V to earth.

    The cables specified in this part of BS4553 have a central phase conductor insulated with PVC and a concentric layer comprising bare copper wires (earth continuity conductor) and copper wires covered with extruded polymer (neutral conductor)...


    6 Insulation

    The insulation shall be PVC compound type TI 1 conforming to BS 7655-3.1...


    9.1 Neutral conductor

    ...To distinguish the neutral conductor from earth continuity conductor, each wire shall be covered by extrusion with a black polymeric compound to a diameter approximately the same as that of the individual wires of the earth continuity conductor.


    9.4 Application of concentric layer

    ...The wires forming the neutral conductor and earth continuity conductor shall be applied in individual groups over the insulation or bedding with string separators.

    Either one or two string separator(s) shall be located on either side of the group of bare copper wires to separate it from the group of coverered wires.    "


    Note that the covering of the neutral conductor is NOT described as, or required to be, INSULATION. It is there simply to ensure the neutral conductor is easily distinguishable from the earth continuity conductor. Unlike the INSULATION required on the phase conductor, which must comply with the relevant standard (BS 7655-3.1), there is no such requirement for the COVER on the neutral conductor.


    This is not to say that the material covering the neutral conductor will not pass an Insulation Resistance test, but just that it is technically NOT insulation; what would happen if it failed an IR test (neutral to earth) next week, next year, whatever...


    In fact, with regard to testing, BS 4553 states the following:


    "Annex F (normative)

    Insulation resistance test

    After completion of the voltage test given in 16.3, measure the insulation resistance between the central phase conductor and all the wires comprising the concentric layer, after applying a minimum voltage of 500 V d.c. for 1 min.    "


    There is no requirement to test between neutral and earth, because on paper there is no "insulation" between them.


    I am aware that some specifications are written to overcome the lack of insulation on the neutral conductor of "standard" split concentric cable to BS 4553. For instance, here is an excerpt from one such specification (regarding street lighting supplies) (the underline emphasis is mine):


    "Split Concentric Cable


    Specific Requirements : Cable for electricity supply complying with BS 4553 (unless stated) and having a voltage rating of 600/1000V, and comprising;

    ...

    (d) Neutral Insulation - black PVC compound providing an Insulating layer. This PVC compound shall comply with type T11 of BS 6746. It shall be applied by an extrusion process and shall form a compact homogenous layer. The final conductor plus insulation diameter shall be approximately the same as that of the individual wires in the earth continuity conductors...

    Note : Subsection (d) above deviates from BS 4553.    "


    So, unless you are using a non-standard split-concentric cable, the neutral conductor is NOT insulated.


    Brian

  • 0
    I’m sure it used to be more like a blue varnish than actual insulation, which is why I was on the point of quibbling.


    Andy Betteridge
  • 0
    The covering was originally a blueish black, (painted) Andy, later insulated. While it was a DNO cable, still millions in use, I cant remember seeing any for "wiring regulations" use. The neutral / earth cores were separated by rubber strands.Perhaps the Wiring regs guys can fill us in. If its in the 18th, (and I don't think it will be), then Martyn is in the clear. Regards UKPNa4a5cb064e47f2dbede49de318fb2e84-huge-img_20190916_222938.jpgThe pic is a 1960s BNO, still in use!

  • 0
    The newer standard ( BS 7870) cables have fully insulated neutrals, rather than the coated conductors, covered with polymeric blue insulation. I have a mock up meter board with a series 8 head and meter with a split con. cable supply and an earthing conductor to an earth block. for teaching purposes. Before I remove the chamber under the cut out most student say the means of earthing is PME, when I remove the chamber they change their minds. Then I take off the head cover and show them the removable link. I expalin that if this head is on the BNO network the link must be removed.


    If someone can tell me how to post a photo here I will post a photo of a 3 phase BNO supply with split con. terminated in a series 8 head?
  • 0
    one way to post a pic here
  • 0

    perspicacious:
    but a building network, by definition, isn't a consumer's installation.


    Where is this defined Andy?


    Regards


    BOD




    I'm working from the The Electricity Safety, Quality and Continuity Regulations which has the following as part of its definitions:



    “consumer” means any person supplied or entitled to be supplied by a supplier but in

    regulations 24, 25 and 26 shall not include, in respect of any supply to meet haulage or

    traction requirements, any person who is an operator of a network within the meaning of

    Part I of the Railways Act 1993(b);


    “consumer’s installation” means the electric lines situated upon the consumer’s side of the

    supply terminals together with any equipment permanently connected or intended to be

    permanently connected thereto on that side;


    “distributor” means a person who owns or operates a network, except for a network where

    that person is an operator of a network within the meaning of Part I of the Railways

    Act 1993;


    “supplier” means a person who contracts to supply electricity to consumers;





    As it's each flat occupier who will have a contract with their own chosen supplier (FlyByNight Energy or whatever) for the supply of electricity, and as the BNO doesn't have a contract or any other entitlement with any supplier for the supply of electricity, it doesn't (to me) seem to fit the definition of a "consumer". More likely it's just a type of "distributor".


    The prohibition on CNE in Regulation 8(4):



    A consumer shall not combine the neutral and protective functions in a single conductor

    in his consumer’s installation.



    only applies to consumers - not to distributors - as far as I can tell.


    As I said, for a new BNO, it's not going to make any difference since the DNO's rules will demand SNE nowadays anyway. But if you're in the situation of dealing with one of the "inherited" BNOs that was originally constructed to distribution standards with CNE throughout, it might be a significant difference.


    Of course there might be some other/later legislation that covers the use of CNE conductors that I'm not aware of...


      - Andy.

  • 0

    This cable is BS 7870, split concentric, a distribution (DNO) cable. This is used in a "wiring regulations" environment, if it is not recognised in the regs it must be detailed as a "deviation."



    I'd suggest that BS 7671 doesn't have a list of acceptable cable types - although it does (perhaps just for the convenience of the reader) list and provide data for some common types. I think all the cables listed in BS 7671 are for LV use - yet BS 7671 has a much wider scope these days - from SELV door bells to 12V electrics in caravans - yet bell wire isn't listed nor are automotive cables (usually to ISO 6722).


    The fundamental requirement is for all items to comply with an appropriate BS or HD, or in the absence of such a standard to an international standard or appropriate standard of another country. If a cable meets any of those, there's no deviation.


    Of course a cable needs to be suitable for its intended purpose - and just complying with some random BS is no guarantee of that.


      - Andy.

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