Reducing Risk When Performing Energized Work on Batteries

Electrical safety guidance in NFPA 70E for work on batteries can be substantially improved. Article 120, Establishing an Electrically Safe Work Condition was originally developed to manage electrical sources that can be de-energized, e.g., facility ac/dc power circuits. Some have inappropriately attempted to apply electrical safety practices intended for power distribution circuits to battery work. This includes attempts to de-energize batteries, verify zero energy, or establish an electrically safe work condition, none of which can be applied to batteries. However, the principles of the control of hazardous energy, including lockout tagout, can and need to be adapted to work on batteries. This paper explores the modifications required to develop a battery hazardous energy control procedure that can protect workers and avoid accidents. The paper also covers several physical properties and engineering controls common in battery systems that affect the battery risk assessment required by NFPA 70E. Lastly, the paper presents a list of changes proposed to electrical safety practices, including those outlined in NFPA 70E, that clarify how to control hazardous energy in batteries, helping to avoid future misapplication of power distribution circuit electrical safety practices to batteries.