Covers units substations of 1000 K VA single phase or 3000 k VA 3-phase maximum, having nominal primary or secondary rating of 600 Volts, for use on circuits having available short circuit currents of not more than 200, 000 amperes, rms symmetrical.Their construction, installation, and use are intended to be in accordance with ANSI/NFPA 70-1984, National Electrical Code.