Calculations of reliability level for some typical HV switchgear schemes is performed in the paper. Calculations of reliability parameters were performed taking into account unscheduled faults of elements of switchgears and also scheduled maintenance works. In the work there are defined substations with typical load (Typical Substations). The definition of typical substations was based on analysis of geographical allocation of loads from different sectors. Methodology for estimation of customer costs of reliability, based on share of load sectors and subsectors in electrical energy consumption, is proposed in the paper with the aim to find customer non-supply costs for substation with high accuracy. Case study included in the paper shows how reliability related costs depend on switchgear scheme type, nominal power of transformers, geographical allocation of substation and shows how to choose optimal HV switchgear scheme for HV/MV substation. It also shows significance of methodology for estimation of customer non-supply costs proposed in the paper.