 together with the Health and Safety at Work Act. location of exceeding start rate more than The engine-generating plant will also generally be found in the centre one hour one hour basement or at ground floor level, where solid foundations to take (years) (years) the relatively high level of floor loading are likely to be found. Additionally, factors to be taken into account will include those of vibration insulation, prevention of noise breakout, clean air induc- 1 in 200 tion and cooling facilities, and the silencing and routing to high level underground of the exhaust system. Any associated fuel storage systems will have 1 in 100 to be accommodated either internally or externally to the building, and appropriate fire and anti-pollution measures, and precautions to underground prevent the fuel freezing, are necessary (Nightingale, 1986). 0.3 to 5MVA 1 in 50 Where very heavy centralised plant rectifiers and batteries are Large town provided, adequate floor strength will clearly be needed, but with the increasing use of distributed or integrated d.c. power plant, the EHV 70% 1 in 200 necessity for purpose built accommodation is markedly reduced or underground eliminated. 1 in 100 Batteries, other than those integrated into purpose built equipment underground racks, may well need specifically designed accommodation, espe- cially where acid leakage, or fumes from battery charging are likely 0.3 to 5MV 1 in 50 to occur. Small town EHV 30% 1 in 200 underground 24.12 Building engineering services HV 20% 1 in 100 Building engineering services ar essential for the operational effi- underground ciency of any modern communications system. Prudent design will 0.3 to 5MVA 1 in 50 ensure that appropriate emergency lighting is included as part of the standby system load capability, and increasingly equipment and other operational accommodation will need to be cooled if plant life and performance is not to be degraded (Howell, 1989). Hence these least being issues of the near imponderables of loss of reputation and loads will