This is an advanced level tutorial on the IEC 62368-1 Edition 3 AC mains port protection component requirements for metal-oxide varistor, MOV, gas discharge tube, GDT, series connected MOVs and series connected MOV and GDT combinations. This document reviews the document entries under these topics, provides commentary and worked examples. Key outcomes are that generally Live to Protective Earth and Neutral to Protective Earth protection for pluggable Type A equipment requires a series connected MOV GDT circuit and that the GDT sparkover required is 2 kV or more. Standards are often difficult to read and interpret. Readers must be aware of the document disclaimer and convince themselves, through reading the referenced standards, that the interpretations herein are correct before acting on them.