Description found in BS7671 18th Edition Regulation 543.7.1.203
"The wiring of every final circuit and distribution circuit intended to supply one or more items of equipment, such that the total protective current is likely to exceed 10mA, shall have a high integrity protective connection complying with one of the following:
(i) A single protective conductor having a cross-sectional area of not less than 10mm, complying with the requirements of Regulations 543.2 and 543.3
(ii) A single copper protective conductor having a cross-sectional area of not less than 4mm, complying with the requirements of Regulations 543.2 and 543.3, the protective conductor being enclosed to provide additional protection against mechanical damage, for example, within flexible conduit
(iii)Two individual protective conductors, each complying with the requirements of section 543. The two protective conductors may be of different types, e.g. a metal conduit together with an additional conductor of a cable enclosed in the same conduit.
"The wiring of every final circuit and distribution circuit intended to supply one or more items of equipment, such that the total protective current is likely to exceed 10mA, shall have a high integrity protective connection complying with one of the following:
(i) A single protective conductor having a cross-sectional area of not less than 10mm, complying with the requirements of Regulations 543.2 and 543.3
(ii) A single copper protective conductor having a cross-sectional area of not less than 4mm, complying with the requirements of Regulations 543.2 and 543.3, the protective conductor being enclosed to provide additional protection against mechanical damage, for example, within flexible conduit
(iii)Two individual protective conductors, each complying with the requirements of section 543. The two protective conductors may be of different types, e.g. a metal conduit together with an additional conductor of a cable enclosed in the same conduit.
Released for: Schneider Electric UK
