“Where the garden spa is an ‘open-air’ type, the location falls within the scope of Regulation 702.11 (basins of swimming pools, fountains and paddling pools, and their surrounds). The requirements of Section 702 should therefore be applied in full for this type of installation.
Basins of swimming pools, fountains and paddling pools, and their surroundings are locations of increased electric shock risk because of the reduction in body resistance and the increased contact between the body and Earth potential due to wet, bare skin. Consequently, such locations are covered by Part 7 (Special installations or locations) of BS 7671, the applicable section being Section 702 (Swimming pools and other basins). Except for areas especially designed as swimming pools, the requirements of Section 702 do not apply to natural waters, lakes in gravel pits and the like.
It must be remembered that in addition to Section 702, all other relevant sections of BS 7671 apply to the above locations (albeit supplemented or modified where appropriate by Section 702). Some of these sections, such as Section 522 (Selection and erection of wiring systems in relation to external influences) and Section 513 (Accessibility), require particular attention.
Early design collaboration and installation co-ordination are needed if significant problems are to be avoided during construction and verification of the electrical installation. Without such collaboration and co-ordination, problems can occur, for example, in relation to the installation of metallic grids in floors where necessary, the installation of supplementary bonding conductors, the positioning of electrical equipment relative to the zones, and the protection of electrical equipment against external influences.
Special requirements, beyond those of BS 7671, may apply to swimming pools for medical use. The electrical installation designer should consult as necessary with the parties responsible for the provision and use of the pool, regarding such requirements.”
Source: Electrical Safety Council’s Essential Guide