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Main equipotential bonding must be provided in each flat in a block of flats.
Snag 16
NICEIC is occasionally asked whether main equipotential bonding should be provided for every flat in a block and, additionally, at the intake position.
CNE denotes combined neutral and earth conductor
In each installation main protective bonding conductors must connect all the extraneous-conductive-parts to the Main Earthing Terminal (MET). (Regulation 411.3.1.2 refers). The requirements apply individually to each flat which has its own supply of electricity given in accordance with the Electricity Safety, Quality and Continuity Regulations: 2002 (ESQCR). This is because the consumer’s electrical equipment of each such separately-supplied unit (for example, the consumer unit, wiring system and accessories) is an ‘electrical installation’ as defined in Part 2 of BS 7671.
Therefore, main bonding conductors complying with Section 544 are required to connect all the extraneous-conductive-parts within the flat to the MET. The main bonding connections to extraneous-conductive-parts such as gas, water, oil or other services need to be made as near as practicable to their points of entry to the respective flat, in accordance with the detailed requirements of Regulation 544.1.2.
The same requirements that apply to the installation of each separately-supplied flat also apply to the electrical installation in the common parts of the multi-occupancy premises (e.g. the landlord’s areas). The extraneous-conductive-parts within such areas must be connected to the MET of that particular installation.
The supply arrangements may vary from those shown in the figure in a number of ways. For example, the meter operator’s metering equipment may be grouped together at a common location, and/or the supplies may not be PME. The principles of application of Regulation 411.3.1.2, however, remain the same.
The electricity distributor may have particular requirements for main bonding, above and beyond those of BS 7671, especially where PME conditions apply. Most electricity distributors publish notes of guidance and/or drawings to explain any such requirements.
Electrical installation. (abbr: Installation). An assembly of associated electrical equipment having co-ordinated characteristics to full specific purposes. Origin of an installation. The position at which electrical energy is delivered to an electrical installation.
In each installation main protective bonding conductors complying with Chapter 54 shall connect to the main earthing terminal extraneous-conductive-parts including the following:
(i) Water installation pipes
(ii) Gas installation pipes
(iii) Other installation pipework and ducting
(iv) Central heating and air conditioning systems
(v) Exposed metallic structural parts of the building Connection of a lightning protection system to the protective equipotential bonding shall be made in accordance with BS EN 62305.
Where an installation serves more than one building the above requirements shall be applied to each building.
To comply with the requirements of these regulations it is also necessary to apply equipotential bonding to any metallic sheath of a telecommunication cable. However, the consent of the owner or operator of the cable shall be obtained.
The main equipotential bonding connection to any gas, water or other service shall be made as near as practicable to the point of entry of that service into the premises.
Where there is an insulating section or insert at that point, or there is a meter, the connection shall be made to the consumer’s hard metal pipework and before any branch pipework. Where practicable the connection shall be made within 600 mm of the meter outlet union or at the point of entry to the building if the meter is external.
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