An explanation of the issues surrounding grounding in traction power systems, why they differ from grounding in industrial and commercial power systems, and recommendations are provided in this recommended practice.

This Recommended Practice covers system grounding of ac and dc traction power systems--those power systems that provide propulsion power for railway and roadway vehicles powered by external power supplies by means of contact lines.

This Recommended Practice is intended to provide guidance on the design of traction power system grounding and fill the need for a grounding recommendation owing to the exclusion of railroad traction power systems by the National Electrical Code. This Recommended Practice is intended for application by engineers involved in the design and specification of new traction power systems, as well as the technical evaluation of existing traction power systems in response to re-definition of operating parameters (e.g., increase in service).