The purpose of the transmission system is to transmit electricity, at a higher voltage, from sources of generation to Bulk Supply Points or Major Substations. The electricity is then stepped down to lower voltages to supply distribution networks, which in turn supply customers.
The transmission network consists of 66 kV lines on steel lattice towers, wooden poles, concrete poles and underground cables. The transmission lines form a ring system and one radial feeder supplying the southern areas of the island. The system load is predominantly to the central part of the island between St. Louis and Wooton and towards the North.
The 66 kV lines interconnect power plants and major 66/22 kV substations. The 22 kV outgoing lines from these substations either supply the rural regions or are used for 'sub-transmission' feeding 22/6.6 kV substations.
Continuous investments are being made to strengthen and maintain the national grid in a superior condition to ensure an efficient and effective network with minimum disruption.