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Earthed Concentric cable in a Commercial Installation

Billy Boy

Hi 

We are carrying out an EICR of a commercial building, and found the external lighting columns fed in a type of Earthed concentric cable, similar to a DNO cable. This cable has an aluminium  solid core with a copper stranded sheath of armouring.

It terminates in to carpark lighting columns in lighting service cut-outs, and feeds approx. 10 columns and emanates from a client commercial building and is terminated in to a standard DB.

(attached some pics) 

I have seen this type of cable in lighting columns within the Road lighting network and service head supplies from network operators but never in a standard BS7671 installation.

The building where the DB is located is PME (TNCS).

Could anyone let me know the compliance Issues with this, first thing comes to mind is the shared neutral and earth ?  etc

Thanks


DOCX

  • 0

    Ah Assuming it is post metering so part of a consumers installation, it is an immediate fail, not of the regs but of the legal requirements of the ELECTRICITY SAFETY, QUALITY AND CONTINUITY REGULATIONS here

    specifically reg 8

    ....

    (4) A consumer shall not combine the neutral and protective functions in a single conductor in his consumer’s installation.

    ....

    So although it would be permitted in many countries, in the UK it is actually illegal.

    (it is also not advised in BS7671, but that is not a legal requirement.)

    regards

    Mike

    PS  the DNO can do this in the street as part of their  distribution network as that is not a 'consumers installation'

    It is the wrong cable it should be

    SWA or  Split concentric

    not plain concentric..

  • 0

    Agree, prohibited, and also will instantly trip any upstream RCD or RCBO that may be later installed.

  • 0

    Is the outer "core" actually a CNE, or is it a neutral (only) and the lamps are TT?  I can imagine that the lamp post itself could be considered an earth rod.

  • 0

    444.4.3.1 

  • 0 in reply to ElectricalCuriousity

    & 444.4.3.2

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