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Main Protective Bonding to incoming Gas and Water services

Hello,

My query is in reference to regulation 411.3.1.2. 

It is in relation to a project where we have a block of flats where we have a new proposed pumped water supply and an existing Gas supply both either sleeved or installed in poly existing the ground externally to the building. This is then connected to steel/copper pipework run externally up the outside of the block spurring off at each level into domestic properties. Where the meter is located and then onto the domestic installation.

There is a difference in opinion between Client and Contractor parties in relation to the need to bond these pipes after the meter/stopcock positions. The Contractor is disputing the need to install equipotential protective bonding at the point of entry (after the meter/stopcock) within each domestic property, as they believe that because the pipework coming out the ground is not extraneous material, they don’t have to bond it.

The Consultant designing and tendering the project neglected to provide any instruction either way.

The other interpretation sits around the specific words “entering the building” and “at their point of entry” within Regulation 411.3.1.2, which could be considered to be in line with each flat being its own “equipotential zone”, and therefore individual buildings, and that there is a possibility of exporting a potential from one flat into another flat, if those installations are not fully installed to recent versions BS7671, which in this case is very likely, as there are a significant number of leasehold properties within the blocks where most of the electrical installations within, date back to the 1960/70’s. There is also the fact that within most of the properties main protective bonding is already in place (apart from the new water supply).

Any assistance is appreciated.

Parents
  • but the building distribution is also covered by BS7671, so cannot logically be a different installation.

    I'm not sure sure. It seems logical to be to be able to have one BS 7671 installation feeding another BS 7671 installation - it's not just abut physics but ownership and responsibility too. You wouldn't want to be reliant on someone else's (parts of the) installation for say isolation or RCD protection where you didn't necessarily have ready access.  We have enough problems with people complaining about not being able to access the incomer to check bonding, earthing arrangements and so on where it's actually part of the same organisation, never mind where it's owned by some completely different 'management company' which sees no benefit in co-operating with piddling little access requests from strangers.

    A consumer is someone supplied by the DNO, even if that is a BNO who also has consumers connected.

    A consumer is someone 'which uses electricity for its own needs' (BS 7671) or 'any person supplied or entitled to be supplied by a supplier' (ESQCR) so in neither case is the BNO a consumer (which is quite convenient where BNO have been obliged to adopt TN-C distribution systems from DNOs, otherwise they'd be in breach of the ban on CNE conductors in consumer's installations in the ESQCR).

    I still think that where the distribution system is TN-C with the N-PE link in each flat (which was common up to the 1980s I think) you'd certainly want main bonding in each flat - if only to avoid 'tingles' between exposed- and extraneous-conductive-parts (never mind the results of any nasty broken PEN situations), so I still think consideration of the individual circumstances is needed.

        - Andy.

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  • but the building distribution is also covered by BS7671, so cannot logically be a different installation.

    I'm not sure sure. It seems logical to be to be able to have one BS 7671 installation feeding another BS 7671 installation - it's not just abut physics but ownership and responsibility too. You wouldn't want to be reliant on someone else's (parts of the) installation for say isolation or RCD protection where you didn't necessarily have ready access.  We have enough problems with people complaining about not being able to access the incomer to check bonding, earthing arrangements and so on where it's actually part of the same organisation, never mind where it's owned by some completely different 'management company' which sees no benefit in co-operating with piddling little access requests from strangers.

    A consumer is someone supplied by the DNO, even if that is a BNO who also has consumers connected.

    A consumer is someone 'which uses electricity for its own needs' (BS 7671) or 'any person supplied or entitled to be supplied by a supplier' (ESQCR) so in neither case is the BNO a consumer (which is quite convenient where BNO have been obliged to adopt TN-C distribution systems from DNOs, otherwise they'd be in breach of the ban on CNE conductors in consumer's installations in the ESQCR).

    I still think that where the distribution system is TN-C with the N-PE link in each flat (which was common up to the 1980s I think) you'd certainly want main bonding in each flat - if only to avoid 'tingles' between exposed- and extraneous-conductive-parts (never mind the results of any nasty broken PEN situations), so I still think consideration of the individual circumstances is needed.

        - Andy.

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