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BS7671:2018 SECTION 708

Phil Kinnaird

Hi all,

At present i stay in a Residential Park home. 

I have raised the matter with with the Site Manager that in my opinion the Connection to the Lodges is not in compliance with BS7671:2018 Section 708. The Electrical supply has been confirmed by the DNO  by visual inspection to be PME.

Section 708 clearly states that a Residential Park Lodge under ESQCR Regulations states that a PME earthing facility shall not be used for the means of earthing for this type of installation.

Unfortunately the Site Manager is digging his heels in stating he has spoken with 2 Electrical Contractors who say it is perfectly OK to utilise this means of earthing and the a Contractor who carried out an EICR Report stated in his opinion the System was not PME despite the DNO confirming it was in an email.

I have advised in my opinion each lodge should have its own earth rod installed to earth the individual lodges.

I did contact the helpline at Certsure which is a helpline run by the NICEIC.

They did advise that in their opinion BS7671 :2018 would apply.

They also provided an extract from UK Power Networks Engineering Design Standard  EDS 06-0017 CUSTOMER LV INSTALLATION EARTHING DESIGN Section 6.9 Mobile Homes which states.

 6.9 Mobile Homes

A PME earthing terminal may be provided to mobile homes if the following criteria are satisfied.

The mobile home is permanently sited

The mobile home is is permanently connected to water and sewerage services

The installation is constructed such that a person in contact with the general mass of earth cannot touch any metalwork connected to the earth terminal

The installation complies with the earthing and bonding requirements of BS7671

If these conditions cannot be satisfied the mobile home shall be treated as a caravan in according with Section 5.6

Refer to BS7671:2018   SECTION 721 for earthen and bonding.

Any comments / clarification would be gratefully received.

Parents
  • 0

    I'll stir it a bit. Ignore the letter of the law for a moment, and look at the reasoning.. The question should be is 'is it dangerous' The problem with a caravan is same as a car on charge, the large area of external metal at suppliers earth potential that may be quite some way from the voltage of the terra-firma ground beneath your feet.

    Is your park home a metal box connected to mains earth, or an electrically insulating one ?
    Mike.

Reply
  • 0

    I'll stir it a bit. Ignore the letter of the law for a moment, and look at the reasoning.. The question should be is 'is it dangerous' The problem with a caravan is same as a car on charge, the large area of external metal at suppliers earth potential that may be quite some way from the voltage of the terra-firma ground beneath your feet.

    Is your park home a metal box connected to mains earth, or an electrically insulating one ?
    Mike.

Children
  • 0 in reply to mapj1

    I think I would rather go with the letter of theLaw just in case something went wrong.

    Most of the Residential Park Homes are supplies Via 3c SWA. Sometimes the SWA is utilised at the Lodge end and sometimes not, relying on an internal core for the Earth. They don't really bother about compliance with BS7671 in the main as the Site Managers answer is "that it is a caravan park".

  • 0 in reply to Phil Kinnaird
    Phil Kinnaird said:
    I think I would rather go with the letter of theLaw just in case something went wrong.

    To do that, you would need to be able to interpret the word "caravan" in the legislation and apply it to the circumstances of the particular installation ...  the legislation being the Electricity Safety, Quality and Continuity Regulations, 2002.

    A court would usually use the legislation, and the relevant Standards (BS 7671 plus standards for the particular caravan or residential park home) ... although the duty is on the distributor in respect of the particular Regulation in question I believe.

    The differentiation in BS 7671 is based on defining not a caravan, but specifically a leisure accommodation vehicle and the differentiator not whether it's transportable from one place to another, but whether it's fully towable on its own per the construction & use regulations.

    As I pointed out earlier, the NCC will be able to help with a query on a particular park home, whether it ought to be classed as a residential park home or a leisure accommodation vehicle from the perspective of BS 7671.

    Such interpretations I don't think (although I may be wrong) the contributors of this Forum could help you with further 'in the general case'.

    Phil Kinnaird said:
    Most of the Residential Park Homes are supplies Via 3c SWA. Sometimes the SWA is utilised at the Lodge end and sometimes not, relying on an internal core for the Earth.

    BS 7671 permits, equally, TT, TN-S or TN-C-S (PME) earthing arrangements for residential park homes that are not classed as leisure accommodation vehicles. BS 7671 also permits, if it suitably sized for the installation, the steel wire armour alone, or a copper conductor in the cable on its own, or both together in parallel, to be a circuit protective conductor, if the earthing arrangement (whether TT, TN-S or TN-C-S) is supplied from the source end of the cable.

    BS 7671 also permits the TT earth electrode to be connected only at the park home end of the SWA cable ... and further permits additional earthing of the circuit protective conductor (supplementary earth electrodes) for TN-S, TN-C-S and TT systems.

  • 0 in reply to gkenyon

    The Park is fully Licensed as a Residential Park Home Site by the Council.

    From the comments received to date it would appear that the general consensus is that it is acceptable to connect to the DNO's PME system.

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