TANESCO owns interconnection power grid made up of generation system transmission and distribution system. Transmission system comprises of forty eight (48) substations interconnected by transmission lines. Transmission lines comprise of 3,340 km of system voltages 220kV, 2,063 km of 132kV; 668 km of 66kV, 24,165 km of 33kV, 6,006 km of 11kV and 71,629 of 0.4/0.23kV totaling 107,871 km by the end of May, 2016

The total installed capacity in the Main Grid System amount to 1357.69 MW as of  May 2016. The system is hydro-thermal mix, constituting hydro 566.79 MW (42%),Thermal plants (Gas – 607.00 MW (45%) and Liquid Fuel 173.4MW (13%) and Biomass 10.50 MW (1%) mainly from IPPs.

The Main Grid System demand from January to May 2016 was 1026.02 MW as recorded on March 15th 2016 at 21:00hrs. The highest grid system demands of 2015 was 988.27 MW recorded on 03.12.2015 at 2100hrs. The transmission system losses recorded in 2012, 2013, 2014 and 2015 were 6.12%, 6.2%, 6.13% and 6.21% respectively. From Jan to May 2016, transmission losses was 6.2%.

Existing Transmission Substation and Capacity

Transmission lines are interconnected with 48 grid substation and 3 off grid substation at voltage levels 66kV and above, the total installed capacity of these substations as at May 2016 is 3674.9 MVA.

TANESCO’s Future Plan

TANESCO future transmission network will include ongoing projects of 400kV transmission line from Iringa - Shinyanga (BTIP), 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