Series Ground Indicator, Explosion-Proof/Dust-Ignitionproof, Copper-Free Aluminum Enclosure. The AEPGI Series ground indicator provides assurance that fuel tanks and other combustible material containers are properly grounded during transfer of the material. This prevents the buildup of a static discharge that could otherwise ignite flammable vapors. The AEPGI Series ground indicator is rated for use in Class I and Class II hazardous environments.