The International Electrotechnical Commission (IEC) documents use a totally different nomenclature to describe the electrical potential between phase conductors and earth than the National Electrical Code (NEC).
Jim Dollard has an extensive background in codes and standards. If you have a query about the National Electrical Code (NEC), Jim will help you solve it. Questions can be sent to firstname.lastname@example.org. Answers are based on the 2014 NEC. Grounding electrode conductor termination