7.2.1 All switches provided for local isolation of Appliances and equipment (including lighting) must comply with BS 3676. The rating of switches must be selected based on the expected load, taking into account any capacitive or inductive effects.
7.2.2 For outdoor locations, damp or wet areas, weather- protected switches must be used (BS 3676).
7.2.3 Wall-mounted switches must not be installed in bathrooms, shower rooms or other locations where normal body resistance is reduced due to the presence of water. In such locations, ceiling mounted cord-pull switches may be used or wall-mounted switches may be used outside the room. Wall-mounted switches may be used in kitchens but at least 2 m from a sink or other source of water.
7.2.4 For areas with higher than normal risk of fire or explosion gas-sealed switches must be used (BS 5345). For example, in gas storage areas, battery rooms, etc.
7
7.2.5 The normal mounting height for switches shall be 1.3 m from floor level. Other mounting heights may be used where there is a specific need, such as, but not limited to, the prevention of access by children or the requirement for access by disabled persons.
7.2.6 Switches with neon indicators must be provided for Appliances such as water heaters, air conditioning units, fridges and freezers, where a visual indication of the presence of power is desirable.
7.2.7 Double-pole switches must be provided for water heaters, air conditioning units and other fixed Appliances operating with or near water supplies.
7.2.8 Cooker control units (isolators) for domestic Installations must comply with BS 4177. The use of cooker control units with an integral 3-pin socket-outlet is prohibited except where the Final Circuit supplying the cooker control unit is protected by an RCD with a residual current rating of 30 mA, in accordance with clause 5.4.9.
[Note: in addition to the above restriction it is considered undesirable to use cooker control units with integral socket- outlets where there is a risk of Appliances or flexible cables supplied by the socket-outlet being damaged by heat from the cooker.]
7.2.9 Flexible cables from switches or isolators to fixed Appliances (such as water heaters, cookers, etc) must be adequately rated and securely fixed with a purpose-made flex outlet plate (which may be integral with or separate from the switch or isolator unit).
7.3
Lighting
7.3.1 Lighting Circuits will normally be fed from 6 A, 10 A or 16 A MCBs from a Final Distribution Board.
7
Components
7.3.2 The rating of lighting Circuits shall be selected in accordance with the number of connection points to be supplied, the type and rating of luminaires to be used, and the Connected Load for the Circuit. A standard method of calculating Connected Load is given in Guidance Note G2 and illustrated in Appendix A20(f).
7.3.3 Lighting Circuits supplying small Edison screw (SES) or small bayonet cap (SBC) fittings must be supplied from Protective Devices of nominal current rating no greater than 6 A.
7.3.4 Switching of Circuits containing discharge lighting or other lighting with high inductance may require special consideration due to high switching voltages that may occur. In order to accommodate the switching voltage in discharge lighting Circuits, the rating of the switch shall be suited to the conditions expected and shall not be less than twice the load current.
7.3.5 High voltage discharge lighting (such as neon signs) must comply with BS 559 and be provided with an emergency isolation switch which must be clearly marked and located in an easily accessible position.
[Note: such switches may be marked “Fireman’s Switch for Neon Sign” or similar wording.]
7.3.6 The connection of mains-operated clocks to lighting Circuits other than through a clock connector unit is prohibited.
7.3.7 All Luminaires must be connected to Final Circuits using a ceiling rose or other purpose made connection point and not directly to such Circuits. Where cables are run within Luminaires they shall be of the heat resistant type, or protected by heat resistant sleeving. See Guidance Note G7(b).
7
7.3.8 Lighting Circuits in false ceilings or voids must be installed in conduit or trunking in compliance with clauses 7.5.12 and 7.5.13. However, short lengths (less than 3 m) of flexible or sheathed cables may be provided between a lighting connection point or ceiling rose and a Luminaire, provided that provision is made for future access and maintenance. In addition, the use of purpose made plug and socket connection systems for Luminaires is not precluded, provided that approval is sought from the Distribution Company. See Guidance Note G7(h).
7.3.9 Luminaires and other light fittings must be installed with due consideration to the weight taken by fixings and supports, and the need for adequate ventilation and heat dissipation.
7.3.10 Heat resistant cables and flexible cords should be used for the connection of high temperature luminaires. See Guidance Note G7(b).
7.3.11 Where light switch boxes contain more than one phase (for large groups of lighting) they must be labelled to indicate the presence of a 400 V supply, and suitable phase barriers should be provided inside the box.
7.3.12 Outdoor lighting should be of suitable weatherproof construction with appropriate connection points and fittings.
7.3.13 Underwater lighting must be supplied by a Separated Extra-Low Voltage System (SELV) not exceeding 12 V a.c. or 30 V d.c.
7.3.14 Emergency light fittings must comply with BS 5266 and shall be provided with a battery of minimum 2 hours rating.