Nigerian suffers from inadequate electricity supply of which her transmission capacity is a major factor. Having deregulated her power system recently , systems planning( generation and transmission) becomes a chicken and egg problem of which its coordination is a complex socio-technical issue. In an effort to approach this problem ,TEPES ( a long term transmission expansion model developed in IIT, Upcomillas , Spain), was used in this thesis to design a tactical transmission expansion plan that will be indicative for both optimal power wheeling capacity and better generator placement up to year 2030. This approach considered the expected generation mix in the Nigerian energy policy.