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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

    Ordinarily, I'd wonder why anybody would be going near the chassis, but then I noticed the stepladders.

Reply
  • 0

    Ordinarily, I'd wonder why anybody would be going near the chassis, but then I noticed the stepladders.

Children
  • 0 in reply to Chris Pearson

    Have had plumber under the lodge Chris clearing a pipe blockage.

    Are you now of the opinion that the Lodges would then be better off with separate Earth Electrodes and separate from the DNO PME Earth.

  • 0 in reply to Phil Kinnaird

    Phil,

    BS 7671 has, for some time, recommended that an additional earth electrode is provided for installations connected to PME (not separate).

    But I think the pictures here clearly illustrate the difference - in the park home here, metalwork connecting to chassis links to ground, quite clearly ... and when completed with cladding etc., difficult to access the metalwork.  Very different to caravan on tyres, possibly also with plastic pads under the lowerable stabilisers ... and possibly in a muddy field ... with parts of the metal trailer chassis still accessible despite the fact that construction of caravans has, too, changed over the years.

    Electric vehicles are more like caravans, as they are on rubber tyres completely, totally separated from local ground.

  • 0 in reply to Phil Kinnaird

    Afraid that I am reluctant to express an opinion. However, I think that we have distinguished between a situation where the chassis is inaccessible from one where it is accessible.

    Any danger to e.g. a plumber could be eliminated by isolating the supply during maintenance underneath the lodge. However, my point was that if the void is being used for storage, particularly of a large metal object, the resident could be in contact with the chassis on a reasonably regular basis.

  • 0 in reply to Chris Pearson

    Agreed ... but  in contact with the chassis.but with what area, and what exactly to form a circuit to cause a hazardous voltage or current?

  • 0 in reply to gkenyon

    OK, this is how I see it.

    For planning purposes, the home is a caravan.

    For electrical purposes, it is a building and not a caravan as defined in BS 7671.

    It is unclear whether the chassis is an extraneous conductive part or not. It appears to rest on a concrete pad, so probably not. However, if it is an extraneous CP, it should be bonded i.a.w. 411.3.1.2(v) because it is an exposed metallic structural part of a building.

    Were the chassis inaccessible (or possibly accessible only by using a tool) and not connected by metal to anything inside the building, it would not need to be bonded even if it were an extraneous CP because it would not be exposed.

  • 0 in reply to Chris Pearson

    The Caravan / Lodge sits on a concrete pad. Not sure if anything else inside building connected and accessible.

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