NFPA 921 Guide for Fire and Explosion Investigations considers the technique arc mapping to be one of the methodologies used in isolating a fire’s origin and spread. Provided the technique is used properly and understanding its limitations, it is a tool for investigators. Synthesized here is the latest peer-reviewed research and discussions on the implications of increased use of ground- and arc-fault circuit interrupters on arc mapping analysis. Incorporated are case studies and evaluations of recent legal decisions. The goal is to arm investigators with what’s needed to maximize the arc mapping’s efficacy and best present its use and results.