08.01 What is a generator base, sub-base, or belly tank?

Generator base, sub-base, or belly tank is a UL 142 fuel tank that is built into the frame of a generator support typically as part of a packaged unit that includes an enclosure. The tank acts as a substitute for a free-standing day tank.

Sub-base tanks can be classified as UL 142 double wall, L 142 single wall with containment dike, or UL 2085 fire rated.