Time domain reflectometers, or TDRS, indicate the source of a fault in an electrical cable system, and in particular underground cables. Cable faults can be defined as damage to an electrical cable that causes resistance and may eventually be the root of a voltage breakdown. Common types of faults include screening faults, which constitute conductor and screen contact, phase faults, contact between multiple conductors, sheath faults, in which the cable screen is exposed to outside contact, and faults do to moisture or a cut cable. All of the preceding cause some form of resistance which disrupts the electrical current. TDRs diagnose faults by sending a pulse through the cable and measuring the response, which will reveal where on the cable the fault is and the magnitude and variety of its resistance.