[Chapter 11] details exactly which installations are covered in the Regulations. The Regulations apply to all electrical installations except those relating to railway rolling stock, ships, offshore oil and gas rigs, aircraft, mines, quarries, radio interference equipment, lightning conductors other than bonding them to the electrical installation and those aspects of like installations covered by BS 5655. The 16th Edition includes, for the first time, installations associated with swimming pools, saunas, highway power supplies, street furniture and caravan parks and pitches.

Although the Regulations cover them, certain types of installation such as electric signs, emergency lighting, flameproof systems, fire detection and alarm systems, telecommunication systems and surface heating devices, are not fully covered. In such cases, the appropriate BS (British Standard) must be consulted as well as the Regulations.  IEE Guidance Notes, particularly Note 4 (Protection Against Fire) give useful information Equipment used as part of an installation but not constructed on site (a good example is switchgear) is not directly covered except that it is required to comply with the appropriate BS.

The Regulations apply to all installations fed at voltages included in the categories Extra-low-voltage and Low-voltage. The values of these classifications are shown in {Table 2.1}.