How do determine the phase sequence of a 3 phase system?

To determine the phase sequence of a three-phase system, you can use a phase sequence indicator or a voltmeter. Connect the phase sequence indicator to the three phases (A, B, and C) and read the display; it will indicate the sequence as either clockwise (ABC) or counterclockwise (ACB). Alternatively, measure the voltages between phases using a voltmeter; the phase with the highest voltage at a given time indicates the leading phase, allowing you to deduce the sequence. Always ensure to follow safety precautions when working with live electrical systems.