TANESCO owns interconnection power grid made up of Generation system Transmission and Distribution system. Transmission system comprises of fifty - five (55) Substations interconnected by transmission lines and sixty - eight (68) are primary distribution substations. Transmission lines network comprises of 3010.7 km of 220 kV, 1672.57 km of 132 kV, 543 km of 66kV and 670 km 400kV Iringa - Shinyanga transmission line while 400kV Kenya –Tanzania interconnection (Namanga – Singida) is on construction stage. Totaling 5896.27 km of transmission lines by the end of November, 2018.

The total maximum installed capacity in the Main Grid System amount to 1,565.72MW as of December 2018. The system is hydro-thermal mix, constituting hydro 573.7MW (36.64%), Thermal plants (Natural gas power plants 892.72 MW (57.02%), and Liquid Fuel 88.80MW (5.67%) and Biomass 10.5MW (0.67%) mainly from IPPs.

The Main Grid System demand from January to December 2018 was 1,116.58 MW as recorded on November 30th 2018 at 20:00hrs. The highest grid system demands of 2017 was 1051.27MW recorded on 14th February 2017 at 2100hrs. The transmission system losses recorded in 2012, 2013, 2014, 2015, 2016, 2017 and 2018 were 6.12%, 6.2%, 6.13%, 6.21%, 6.15%, 5.91% and 5.88% respectively.

Existing Transmission Substation and Capacity

Transmission lines are interconnected with 52 grid substation and 3 off grid substation at voltage levels 66kV and above, the total installed capacity of these substations as at December 2018 is 4346.9MVA. Optic fiber length for communication within substations are on the total route of 3120km.

TANESCO’s Future Plan

TANESCO future transmission network will include projects which are at inception stages includes 400kV line from Masaka – Mwanza, 400kV line from Mtwara – Somanga Fungu, 400kV line from Somanga Fungu – Kinyerezi,,  400kV line from Rufiji – Chalinze – Dodoma, 400kV line from Nyakanazi – Kigoma – Mpanda – Sumbawanga,, 220kV line from Geita – Nyakanazi, 220kV line from Bulyanhulu – Geita,  220kV line from Rusumo – Nyakanazi, 400kV line from Singida – Arusha – Namanga, 132kV line ring circuit for Dar es Salaam (TEDAP), 400kV line from Iringa - Mbeya – Sumbawanga, 400kV line, 400kV line from Mtwara – Songea, 220kV line from Kibaha – Bagamoyo, 220kV line from Ruhuji – Kisada.