The National Electrical Manufacturers Association (NEMA) published NEMA PB 2.2-2014 Application Guide for Ground Fault Protective Devices for Equipment.
PB 2.2 was developed by the NEMA 05LVDE-02-PB Technical Committee, and is a guide of practical information containing instructions for the safe and proper application of ground fault protective devices. This standard is useful in commercial, industrial, and manufacturing applications where ground fault protective devices are applied in equipment.
It should be noted that PB 2.2-2014 revises and supersedes PB 2.2-1999 (R2004, R2009).
PB 2.2 may be downloaded at no cost or purchased in hard copy for $91 on the NEMA website.