Equipotential Zone Grounding and Bonding at 4.16-/13.8-kV Switchgear and Loads Why’s / Challenges / How’s?

This paper will focus on the potential hazards when providing equipotential zone grounding and bonding systems for workplace scenarios involving medium voltage equipment such as those addressed by the National Electrical Code (NEC), ASTM F855, and the Occupational Safety and Health Administration (OSHA) and other jurisdictions having authority. Equipotential zone (EPZ) electrical grounding and bonding play an important role in ensuring worker safety in medium voltage switchgear installations, by reducing the risk of electrocution and arc flash injury from hazardous levels of voltage rise. However, improperly applied temporary protective grounds can increase electrical hazards under certain conditions. EPZ grounding and bonding systems are crucial to ensuring the safety of personnel in medium voltage switchgear installations by ensuring that any electrical fault current is quickly and safely redirected to ground. It requires careful design, installation, testing, and maintenance to ensure that it is functioning properly and providing adequate protection. Best practices for temporary protective grounds (TPGs) and grounding truck set ups for work on electrical loads remote from the switchgear will be discussed. The importance of overcurrent protective devices (OCPDs) will be emphasized. LO/TO best practices, as rigorous and robust, will be stressed. Hazards will be identified, the potential severity and damage to health will be estimated and hierarchy of risk controls will be as per NFPA 70E and CSA Z462 and other applicable standards. The paper will cover power generation, industrial and the construction electrical sectors.