The Occupational Safety and Health Administration (OSHA) regulates almost all workplaces in the United States. Part of this regulation includes providing standards for flammable aerosol storage cabinets and any grounding requirements. Based on a series of OSHA definitions and laws coupled with announcements from the National Fire Protection Association (NFPA), OSHA does not require grounding a flammable aerosol storage cabinet.
Aerosol as Liquid
The requirement to store flammable aerosols in an OSHA compliant storage cabinet begins with OSHA Standard 1910.106(a)(1). As defined by OSHA, aerosol means "a material which is dispensed from its container as a mist, spray, or foam by a propellant under pressure." Next, OSHA Standard 1910.106(a)(13) defines a flammable aerosol as an aerosol required to be labeled "Flammable" under the Federal Hazardous Substances Labeling Act (15 U.S.C. 1261). For the purposes of storing flammable aerosols, they are considered Class IA liquids.
Flammables cabinet requirements
For OSHA, a Class IA liquid has a flashpoint below 73 deg. F. and a boiling point below 100 deg. F. OSHA Standard 1910.106(d) requires storing Class IA liquids of a certain amount in specially designed storage cabinets. OSHA Standard 1910.106(d)(3)(ii)(a) governs metal containers, while Standard 1910.106(d)(3)(ii)(b) gives design and construction requirements for wooden flammable cabinets. Quoting OSHA regulations, cabinets constructed in the manner prescribed "shall be deemed to be in compliance." In these standards, neither the metal nor wooden flammable storage container rules include a grounding requirement.
NFPA grounding cabinets
OSHA works closely with the National Fire Protection Agency (NFPA), incorporating NFPA standards as OSHA rules and using NFPA standards when testing flammable cabinets for fire resistance. On the NFPA website, one frequently asked question notes some flammable liquids storage cabinets have grounding screws. When asked if NFPA standards require electrically grounding the cabinet, NFPA's response is no. "NFPA 30 does not require that the cabinet itself be grounded. Many manufacturers provide a grounding screw on their cabinets as a convenience to the user."
Storing versus dispensing
Lab Safety Supply offers this explanation why a safety cabinet may come with a grounding lug. "Safety cabinets are not required by federal regulations to have a grounding point; however, in order for that cabinet to receive Factory Mutual (FM) approval, it needs to be equipped with one." One situation requiring grounding a cabinet would be when dispensing Class I liquid from a storage cabinet while the aerosol remains in the cabinet. Standard 1910.106(e)(6)(ii) requires grounding when dispensing a Class I liquid into another container. Avoid the requirement for grounding the storage cabinet by using the storage cabinet for just that--storage only. Do not dispense a flammable aerosol from a storage container.