Twin & Earth PVC Cables in Light Commerical Building

I visited a Highstreet ground floor building which has plans to be refurbished from a restaurant to a bathroom showroom. The electrical installation has been carried out in 2021 using twin & earth PVC sheathed cables. Because of the Covid pandemic the restaurant owners never opened and the electrical installation is not fully complete with the final fix of the wiring accessories still required. There is no electrical installation certificate. (Final circuits have all been wired into distribution boards). There is suspended plasterboard ceiling throughout.

The new owners are planning to refurbish the restaurant to a bathroom showroom with the intention to utilise the existing twin and earth PVC wiring and get an electrical installation certificate.

Question: Is twin and earth PVC sheathed cable suitable? Their electrician has told them he will not be able to provide them with an electrical installation certificate because cables need to be LSF type without giving them a reason why.

  • Seems a bit odd - can you find a specific reference to this requirement in BS7671?

  • I have gone through BS7671 and can not find any reference to it

  • LSF or LSHF? See https://www.fscables.com/other/blog/lsf-vs-lshf-lszh-there-is-a-difference.html

  • Hi DevV. Due to its fire safety advantages, LSHF cable is preferable for use in areas with high fire risk. T&E PVC Might be unsuitable in a high street building with restricted exit routes. There is no specific regulation for a bathroom showroom. Reg 422.6 talks about locations of national, commercial, industrial or public significance needing cables with improved fire resisting characteristics. Have a read through chapter 42 to see if any of those regulations apply to your installation.

  • I've a feeling this sort of thing is covered by the The Construction Products Regulation and the requirements haven't (yet) been incorporated into BS 7671. (Although I think they may have found their way into some similar standards (e.g. B 6701 for telecoms wiring)).

    It all seems a bit vague to me in terms of actual specific requirements for particular premises at present - but others here will know more and might be able to explain far better than I can.

    A bit of bedtime reading: https://www.basec.org.uk/resources/electricians-guide-to-cpr/

       - Andy.

  • Is it on the designer to consider factors which may affect the safety of the occupants when specifying cables type in areas with high levels of public. I believe LSZH for example should be considered where high smoke levels would be likely to produce injury or panic, along escape routes 

  • In the UK, whilst BS 7671 recognises that `where applicable, cables need to meet CPR requirements and carry a Euroclass for fire performance`

    the onus for selection of types of cables lays with the designer, consultant, specifier, installer for the installation. as per BS 7671 - Appendix 2 (informative) specifically item 17, the DLUHC `has not exercised these powers in respect of reaction to fire for cables`

  • Might be worth looking at

    BS EN 50575 which became a legal requirement in July 2017

  • For protected escape routes cables need to be LSZH according to 422.2.1 so low flame propagation and low smoke emission.