Medium Voltage cables, or MV cables, is a category defined by the International Electrotechnical Commission (IEC) as having a voltage rating of above 1kV up to 100kV. There does, however, remain some ambiguity over where the medium voltage cable band begins and ends, depending on the countries, the standard setting bodies, and the type of system used as historically engineers only referred to low voltage and high voltage. The concept of medium voltage was only introduced as the level of voltages increased and the need arose for a greater classification range, which now often includes extra low and extra high voltage.