Ga, Gb and Gc are protection classes applied to equipment for use in explosive gas atmospheres, and they constitute an indispensable part of explosion-proof equipment markings.

※ Ga: Equipment for use in explosive gas atmospheres with a "very high" protection class. It is not an ignition source during normal operation, anticipated faults or rare faults. Equipment with the Ga protection class can be used in Zone 0, Zone 1 and Zone 2.

※ Gb: Equipment for use in explosive gas atmospheres with a "high" protection class. It is not an ignition source during normal operation or anticipated faults. Equipment with the Gb protection class can be used in Zone 1 and Zone 2.

※ Gc: Equipment for use in explosive gas atmospheres with a "general" protection class. It is not an ignition source during normal operation, and additional protective measures can be adopted to ensure it does not cause effective ignition in scenarios where ignition sources frequently occur (e.g., malfunctions of lighting fixtures). Equipment with the Gc protection class can be used in Zone 2.

As is widely known, Zone 0 is the most hazardous area, and only equipment meeting the Ga protection class can be used for protection. Therefore, the Ga protection class is higher than the Gb protection class.