Provincial Electricity Authority (PEA) has a submarine cable project to Koh Tao in Surat Thani Province, Thailand to increase the capacity, stability and support the growing demand for electricity in Koh Tao due to a high economic growth rate. At present, Koh Tao uses electricity from diesel power plants resulting in high costs in maintenance, fuel, and electricity, causing PEA to bear many losses each year. Investment in the construction of a distribution system linked by submarine cable is a project that uses a lot of investment cost in constructions and in each construction also affects the environment as well. Thus, there must be an effective method of calculating the investment value to ensure that the investment projects are appropriate and cost-effective throughout the life of the asset. This paper presents the analysis of the financial feasibility of the submarine cable project to ensure that it will have economic benefits and be effective throughout the asset utilization period with life-cycle cost analysis. In this paper, three alternatives are simulated, and the life-cycle cost (LCC) of all three alternatives are calculated. Then, the analysis is performed to find which options are worth the most investment. Common network asset indices methodology (CNAIM) is applied to determine the age of the submarine cable used in the project. In addition, this method can be used to find the probability of failure (PoF) of the submarine cable which is an important parameter and is used to calculate in the LCC model to achieve the purpose of this paper.