Definitions used on this website:

Main bonding, supplementary bonding and equipotential bonding are all terms referring to means of safety electrical earthing.

BS7671:2008 (as amended)

BS7671:2008 (as amended), also known as the 17th edition of the wiring regulations is a document produced by the Institution of Engineering and Technology, together with the British Standards Institute and is the common standard used for the design and maintenance of electrical installations. It is not mandatory, but can be used at law.

Class I

Class I devices are items of metallic equipment requiring an earth connection for safety purposes.

Competent person scheme

These are schemes run by government approved bodies for the registration and control of installers engaged in domestic installation work.

Defined parts of an electrical installation

Part P of the building regulations is concerned with  alterations to specific parts of an existing domestic electrical installation, whereas the whole of a new installation would require Part P compliance.

Part P of the building regulations

See above


Installation Condition Reports are modified PIRs and are used to assess the state of an existing electrical installation only. They can only be used for the certification of a new installation when directed by building control or other unusual circumstance.


Institution of Engineering and Technology


While this can also stand for Passive Infra Red detector, in this instance it stands for Periodic Inspection Report. Periodic Inspection Reports are the official name for test and inspections. These have now been superseded by Installation Condition Reports (see above).


An electro-mechanical safety device designed to protect against earth faults. They can prevent injury or death by electrocution.


Bs7671 has tabulated ohmic values of maximum resistance for electrical circuits. If any circuit exceeds its design value, then the circuit protective device (fuse) may not automatically disconnect the circuit in time to prevent electrical damage under fault conditions.