Orange Alu Split Con

For clarification spit con allows a separate neutral and earth (SNE in DNO literature) so presents as TNS. Note that in a building network it is quite likely to still be TNC-s at the origin, so questions like is the main water bond at the origin, and any bonding in the flat supplementary, or is the flat bonding also main bonding, so what size should it be, can cause some dispute. (not as much grief as twin and earth sub-mains though, where the undersize CPC can be a real pain.)

The construction is the same sort of 'coax cable' as  earthed concentric, but half the outer layer is earth and bare, and the other half is insulated to form the neutral




Termination requires the neutral strands to be individually stripped and marshalled. Comparing sizes for the same current capacity it is more flexible than SWA, but BS7671 does not consider  it to have an all-encompassing earthed screen or armour so routing  options are a bit less liberal. (again, not as bad as T and E)

Managed to find a supplier in Woking who has 35mm on the shelf, just need to check if 35mm will fit in to the old marshalling point terminals! 

although the neutral and earth are separate in the BNO network to comply with BS 7671

Is it really a BS 7671 requirement? I thought BS 7671 permitted CNE/PEN conductors in some circumstances (section 543.4). AFAIK the old requirement for "authorization" (from a secretary of state for summat or other) disappeared with the old Electricity Supply Regulations - so there's no requirement for any authorization in the UK as far as I can tell. The new ESQCR simply has a blanket ban on combined conductors in consumers' installations of course - but a building network, by definition, isn't a consumer's installation.


Don't get me wrong, I'm not the least in favour of CNEs inside buildings (I'm not that keen on them outside buildings either) - but I suspect it's more a matter of complying with the DNO's technical standards (which at long last are recognising some of the problems with diverted N currents) than BS 7671.


   - Andy.

Andy


You cannot combine the neutral and earth in a BNO network. Most DNOs publish policy documents for BNOs to comply with if they want the DNO to connect the installation to the DNO supply.


You can only combine neutral and earth if the installation is connected to a private transformer or generator or if licensed to do so.

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."


Regards, UKPN.

The construction is the same sort of 'coax cable' as  earthed concentric, but half the outer layer is earth and bare, and the other half is insulated to form the neutral


Is the "insulation" adequate insulation?


Is it half and half? 


Regards


BAD

I can’t see that the insulation is any better or worse than that of BS6004 cables, given it has a BS as a cable I see no issue. 


From the SY/YY/CY debate


’Regulation 133.1.1 requires that every item of equipment (including cable) must comply with the appropriate British or Harmonised Standard.’


Clearly BS7870 is a british standard to which this cable claims its compliance.


This combined with the 100s of 1000’s of installed meters in BNO networks the country over, would seem to suggest brains far superior to mine consider it no issue.


Ultimately this will be before the head & the meter so will not appear on the domestic certificates for the flats. 


Cheers


Martyn  

12 March 2006 09:37 PM

briandoherty Posts: 313 Joined: 08 May 2004

BS7671 Regulation 522-06-06 currently allows split concentric cables (to BS4553) to be installed outside "safe zones". However, one of our engineers queried such an installation with the IEE and with the relevant panel (Panel B of the national committee JPEL/64) of British Standards. Our point was that with split concentric cable, the neutral conductor is: a) not insulated (BS4553 does not call for "insulation" on the neutral conductor, but just calls for it to be identified by a polymeric extrusion to distinguish it from the concentric earth conductor) and b) not protected against mechanical damage, as it would be if the cable was armoured. The IEE / BSI committee agreed with us, and confirmed that insulated concentric cables should be removed from the associated parts of BS7671 by the time the 17th edition is issued (January 1st 2008) or sooner if an amendment is issued before then. Brian

That didn't copy and paste very well and attempts to edit it failed!


Regards


BOD