The prospective short circuit current (PSCC) is the highest electric current which can exist in a particular electrical system under short circuit conditions. It is determined by the voltage and impedance of the supply system. It is of the order of a few thousand amperes for a standard domestic mains electrical installation, but may be as low as a few milliamperes in a SELV (Safety Extra Low Voltage or, occasionally, Separated Extra Low Voltage) system or as high as hundreds of thousands of amps in large industrial power systems.