Abstract: A system that protects telecommunications equipment from AC power faults and voltage transients comprising (1) a high-energy foldback device between the current-carrying lines of a telephone system and ground; (2) a voltage clamping device between the current-carrying lines; (3) a foldback device between the current-carrying lines and ground; (4) a first overcurrent protection device connected in series with the above foldback device; and (5) a second overcurrent protection device in the lines between the high-energy foldback device and the above mentioned serially connected foldback device and first overcurrent protection device. The system may be used, for example, with standard telephone lines, PBX out-of-building lines, special service lines such as carrier, pair-gain, and high speed data, and dedicated voice-band services such as pay phones and traffic-control communication lines.