A device for limiting a short-circuit current in an alternating-current low-voltage installation includes one or more supply lines having power-supply points with power-supply aggregates protected by feeder switches. The supply lines are separated at an isolating point into two line sections in response to a short circuit fault. One or more polyphase high-speed short-circuiting devices are coupled to the isolating point, having a current carrying capacity sufficient for short-circuit current intensities occurring on the supply line. The high-speed short-circuiting device performs a short-circuit switching operation at the isolating point in response to a trip signal. Two power circuit breakers are each connected in series between each of the line sections and the high-speed short circuiting device. A current-sensing device is coupled to each line section. The current-sensing device detects the short circuit fault, and transmits the trip signal to the high-speed short circuiting device.