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General Technical FAQ's

  • How close to a sink/basin can a socket outlet be located?

    BS 7671 does not specify any minimum distance for socket-outlets to be from a sink. However, regulation 512.2.1 requires external influences to be considered when selecting equipment for a particular location. Accessories used in domestic installations are not designed to be splashed and therefore not suitable for installation close to a sink or draining board. For this reason, it is recommended that socket-outlets and other accessories should be located at least 300 mm, measured horizontally, from a sink or draining board, where they are less likely to get splashed.

  • Can I certify other contractors' work if I am a member of a Competent Persons' scheme?

    No; the Competent Persons' schemes are self-certification schemes. You cannot certify somebody else's work through your scheme provider. You can, however, provide a Periodic Inspection Report or complete the testing section of an Electrical Installation Certificate provided that you have inspected the work during the construction phase.

  • Does the connection of equipment, i.e. cookers/boilers, etc. require notification under Part P?

    No; connection of equipment to an existing point is not notifiable work even in a special location or a kitchen.

  • Can I install a spur off an existing circuit without being registered on a Competent Person scheme?

    You can install a new spur from an existing circuit without being registered on a Competent Persons' scheme provided it is not in a special location or a kitchen.

  • Do I need to provide protection for cables buried in walls?

    Mechanical protection of cables directly buried in a wall is not required if it is installed in one of the following zones:

    Within 150 mm from the top of the wall or partition;

    Within 150 mm of an angle formed by two adjoining walls or partitions;

    The cable is running either horizontally or vertically to an accessory or switchgear on the wall. This zone now extends to the reverse side of a wall or partition 100 mm thickness or less if the location of the accessory or switchgear can be determined from that reverse side.

    If installed outside of these zones, the cable must have an earthed metallic sheath or be enclosed in earthed metallic conduit/trunking or be buried at a depth of more than 50 mm or be mechanically protected from penetration by nails/screws etc.

  • Where pipework in a bathroom is plastic, do I need to supplementary bond the bath/radiator, etc?

    No; if the pipework is substantially plastic with only short metal stubs connecting the taps/radiators, etc. these can be treated as isolated pieces of metalwork and do not need to be bonded.

    On metal pipework installations, under the 17th Edition, provided all the circuits of the location are protected by a 30mA RCD and there is continuity between the extraneous conductive parts and the protective (main) equipotential bonding, then supplementary bonding is not required.

  • Do I need to provide RCD protection on a shower circuit?

    Under the 17th Edition, all circuits in a bath/shower room require 30mA RCD protection.

  • Can a PME supply be used to supply a swimming pool?

    If a swimming pool forms part of an installation and the supply to that installation is PME, then all metalwork and pipes should be separated from the rest of the installation and connected to an earth electrode. If this is not practical, then a metal grid will need to be installed in the floor around the pool and shower areas and supplementary bonded. In either case, the installation should be protected with an RCD.

  • Do I need to provide supplementary bonding in a commercial kitchen?

    Supplementary bonding of metal work surfaces, etc, is not a specific requirement of BS 7671. The designer of the electrical installation may, however, perceive there to be an increased shock risk in that particular location and specify additional bonding.

  • Do I need to install main bonding if it is missing or undersized if I am installing a new circuit?

    If you are installing a new circuit and you are relying on automatic disconnection in the event of an earth fault, it follows that you are relying on there being an equipotential zone. To ensure there is an equipotential zone, main bonding to incoming services must be carried out.

    If the main incoming services, etc, are bonded but the conductor is undersized in relation to the current BS 7671 Regulations, you should bring it to the customer's attention and upgrade it if requested.