A structure, usually a small building on a fenced-off lot, that contains any combination of routing or cutoff switches, transformers, surge arresters, capacitors, power conditioners and other equipment needed to insure smooth, safe flow of current. Substations are most commonly seen in residential and industrial areas, where one or more high voltage lines can often be feeding into the station and any number of lower-voltage distribution lines spider out to serve customers in the surrounding area. A facility that steps up or steps down the voltage in utility power lines. Voltage is stepped up where power is sent through long-distance transmission lines. it is stepped down where the power is to enter local distribution lines. IEC intends establishing an additional 21 sub-stations with a capacity of 2,170 MW by 2012 so that there will be a total of 142 substations with a capacity of 16,900 MW in place