The most important thing to understand about ground fault protection devices is that one type is to protect personnel and the other is to protect electrical equipment, the latter having different trip levels for different types of protection.
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 email@example.com. Answers are based on the 2014 NEC. Point of supply