Remote control switches (RCS) can improve reliability of a power system by reducing the total time of fault detection, isolation and restoration. DGs can improve reliability of system if they can provide the loads after switches performance to isolate faults. Then places and sizes of DGs and places of switches have significant effect on reliability improvement. In this paper a dynamic preprocessed genetic algorithm (DAGA) is proposed to enhance benefit of switches in ENS reduction by minimizing the total cost of customer service outage and total cost of line switches in presence of DGs. The feasibility of the proposed algorithm is examined by application to several distribution systems.