The arc-flash hazards of fire pumps: redesigning protection schemes for electrical installations

In recent years, engineers have been redesigning the protection schemes for electrical installations to reduce the arc-flash hazard associated with switching and maintaining equipment. For electrical fire pumps, however, National Fire Protection Association (NFPA) 20, Standard for the Installation of Stationary Pumps for Fire Protection, prescribes very strict requirements for reliability of the power feed and overcurrent protection for an electric fire pump. The result is that current is allowed to flow for a longer time period to ensure that a fire pump may start without nuisance tripping. These requirements are made without consideration for the associated arc-flash hazard. They do not acknowledge that a redundant fire-pump installation can provide equal or greater system reliability, plus greater operator safety, than is possible with a potentially hazardous reliable power feed to a single fire pump. This article will summarize reliability requirements currently mandated for electric fire pumps, discuss the arc-flash impact of those requirements, and propose language that could be incorporated in future code revisions to reduce safety hazards while preserving operating reliability of system installations.