The reliability study is one of the major factor study to design, operation and maintenance of power system. Therefore, the reliability indices are important to be calculated. Based on the target of the study, the index required is calculated. Therefore, in the present study, the Loss of Load Expectation (LOLE) is required to evaluate the system reliability. The LOLE is defined as the number of days per year or the number of hours per year. The calculation of LOLE needs to know the Forced Outage Rate of each generating-unit. Finally, this will help for the smart cities that need to minimize the LOLE. © 2019 Institution of Engineering and Technology. All rights reserved.