The National Electrical Manufacturers Association (NEMA) published NEMA ABP 7-2015 Engineering Series Ratings: Is It Practical? This white paper explains why it is important to understand how series ratings are determined.
An update of a white paper published in 2005, NEMA ABP 7-2015 was developed by the LVDE White Paper Task Force. It discusses 2005 National Electrical Code changes regarding series ratings for circuit breakers.
NEMA ABP 7-2015 may be downloaded free of charge on the NEMA website.