Faulty electrical connections (joints and terminations) may attain high temperatures or emit arcs or hot particles, resulting in the risk of fire or other harmful thermal effects to surrounding materials.
Therefore, irrespective of nominal voltage, BS 7671 requires every electrical connection, except a connection in a protective conductor, to be contained within an enclosure meeting certain requirements. This includes connections in extra-low voltage circuits.
Regulation 526-03-02 calls for every electrical connection in a live conductor or a PEN conductor to be made within one of the following, or a combination of them:
i) a suitable accessory, such as a lighting switch or a socket-outlet, complying with the appropriate British Standard
ii) an equipment enclosure (such as that of a luminaire, distribution board, item of switchgear, or a box forming part of a conduit system) complying with the appropriate British Standard
iii) a suitable enclosure of material complying with the relevant glow-wire test requirements of BS 6458-2.1 – Fire hazard testing for electrotechnical products. Test methods. Glow-wire test
iv) an enclosure formed or completed with building material considered to be non-combustible when tested to BS 476-4 – Fire tests on building materials and structures. Noncombustibility test for materials
v) an enclosure formed or completed by part of the building structure, having the ignitability characteristic ‘P’ as specified in BS 476-5 – Fire tests on building materials and structures. Method of test for ignitability (withdrawn but still referred to in BS 7671).