Voltage

(Of a circuit.) The greatest root-mean-square (effective) difference of potential between any two conductors of the circuit concerned.

• Nominal: A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (as 120/240, 480Y/277, 600, et cetera). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.
• Ground: For grounded circuits, the voltage between the given conductor and that point or conductor of the circuit that is grounded; for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.