TANESCO owns interconnection power grid made up of generation system transmission and distribution system. Transmission system comprises of fifty (50) Substations interconnected by transmission lines. Transmission lines network comprises of 3610.7 km of 220 kV, 1662.47 km of 132 kV, 543 km of 66kV and 670 km 400kV Iringa - Shinyanga transmission line is in operation while Makambako - Songea is in construction stage. Totaling 5816.17 km by the end of May, 2017.

The total maxmam installed capacity in the Main Grid System amount to 1366.60 MW as of  of a June 2017. The system is hydro-thermal mix, constituting hydro 567.70 MW (41.54 %), Thermal plants (Natural gas power plants 615 MW (45.0 %), and Liquid Fuel 173.4MW (12.69%) and Biomass 10.50 MW (0.77%) mainly from IPPs.

The Main Grid System demand from January to June 2017 was 1051.27 MW as recorded on February 14th 2017 at 21:00hrs. The highest grid system demands of 2016 was 1041.63MW recorded on 20.10.2016 at 2000hrs. The transmission system losses recorded in 2012, 2013, 2014 2015 and 2016 were 6.12%, 6.2%, and 6.13%, 6.21% and 6.15% respectively. From January to June 2017, transmission losses was 5.92%.

Existing Transmission Substation and Capacity

Transmission lines are interconnected with 50 grid substation and 5 off grid substation at voltage levels 66kV and above, the total installed capacity of these substations as at June 2017 is 3883.4 MVA.

TANESCO’s Future Plan

TANESCO future transmission network will include ongoing projects of 220kV line from Makambako to Songea, 132kV line from Moshi – Arusha, 132kV Dar ring (Ubungo – Kurasin – Mbagala – G’mboto – Kipawa). Other projects at inception stages includes 400kV Transmission line from Dar es Salaam to Arusha via Chalinze & Tanga, 400kV line from Singida – Arusha, 400kV line from Nyakanazi – Kigoma – Mpanda – Sumbawanga, 400kV line from Mbeya – Sumbawanga, 400kV line Iringa – Mbeya, 400kV line from Mtwara – Songea, 220kV line from Bulyanhulu - Geita, 220kV line from Geita – Nyakanazi, 220kV line from Kibaha – Bagamoyo, 220kV line from Ruhudji – Kisada