This paper presents the method of design of a cable fault location sensor for underground cable fault detection. The aim was to detect the fault location from transmitting or receiving station up to few meters accuracy using an Arduino based kit. The underground cable-based supply system is a common practice in urban areas. As explained in the paper, the system uses the principle of a Varley loop to determine the exact distance of the fault in the underground cable up to the accuracy of a meter. When any fault, e.g. short circuit and earth fault occurs, the length of the fault of the cable can be determined from the fault resistance using the bridge in the Varley loop. A microcontroller is used to make the necessary calculations and display the fault distance after that. After necessary calibration and testing, an accuracy of about 85% is achieved in locating the fault using the method.