A See Note 1
See Note 2 C
NOTE 1 External firespread may be evaluated on the basis of a single storey if, on each storey, there is a fire-resisting partition at A or B or C. NOTE 2
External fire spread should be evaluated on the basis of all four storeys.
Figure 8 â€” Location of fire-resisting barriers to limit fire spread between buildings 28.3 Electrical services 28.3.1 General All electrical services should be installed, and periodically inspected and tested (with any necessary maintenance carried out), by suitably qualified engineers in accordance with BS 7671:1992 (IEE Wiring Regulations). 28.3.2 Electrical power supply The electrical power supply to life safety and fire protection equipment should be separate from all other circuits in the building so that the failure of other equipment does not render the installation inoperative. Each connection to the power supply should be via an isolating protective device reserved solely for the life safety and fire protection equipment and independent of any other main or sub-main circuit. Such isolating protective devices (with high rupturing safety devices) should be clearly labelled and identified as to their purpose. They should be secured against unauthorized operation and should, except for maintenance, be kept locked-on. The supply to these isolating protective devices should be independent of the main switch for the building and be appropriately labelled in accordance with the principles detailed in 16.2 of BS 5839-1:1988. Monitoring facilities should be provided at the central control room (where provided) to show, as far as is reasonably practical, that power is available up to the final control point, e.g. motor contactor, to all fire safety systems. 28.3.3 Protected circuits for the operation of equipment in the event of fire The wiring system should either: a) consist of mineral-insulated, copper-sheathed cables conforming to BS 6207, or consist of cables conforming to the requirements for classification as CWZ in accordance with BS 6387; or b) be protected against exposure to the fire by separation from any significant fire risk by a wall, partition or floor having at least 60 min fire resistance in terms of integrity and insulation from the side of the construction remote from the cable. NOTE 1 fire.
The mechanical protection of cables by conduit, ducting or trunking should not be considered to give protection against
ÂŠ BSI 8 December 2004