 inside the base of the foot of an electric pole, the cables run inside the body of the pole and the antennas are attached to the top of the pole. The local city or municipal authorities generally approve these adaptations, since they do not make any major cosmetic change to the existing structure and utilise the existing framework in providing cellular services to the normal public. If there is not sufficient strength, the existing light pole needs to be modified, reinforced or replaced with a stronger frame of the same size and shape. For free-standing outdoor structures, a BTS can be totally concealed inside a billboard, bus stop or an outdoor advertisement. Many such public installations can be used in a similar fashion, where even the antenna can be mounted inside the same structure and coloured to match the existing structure. In other cases huge commercial signs on frames, located in prime locations like business districts, highway entrance/exit, major crossings, etc., provide adequate space for hiding base stations. A.2.2 Provision of Site Support Elements Normal equipment sites consist of the following constituents: BTS equipment Transmission equipment DC power supply and power distribution board including circuit breakers or fuses Battery backup Tower or pole with required cable trays Antenna with feeder cable Heating, ventilation and air conditioning (HVAC) unit Accessories: fire and smoke alarm, fire extinguisher, door alarm, lighting Generator backup (for remote, critical or rural locations) Site support elements comprise battery backup units, HVAC units, cable trays and also diesel generators. During any maintenance procedure battery backup takes care of the power outage, before it is restored or a diesel generator arranges a backup power. In many rural areas it is often difficult to guarantee 24 hours of electric power supply, hence a diesel generator becomes an integral part of the site. The equipment is housed in a dust-free sealed environment and generates heat during its normal operation. If th