Crouse-Hinds GHG273 Ex-Protected Light Switch is used to prevent arcing of enclosed switch from causing ignition of a specific hazardous atmosphere external to the enclosure. It is used in division 2, zone1 and 2 areas such as chemical plants, oil and gas refineries, paint and varnish manufacturing plants, gasoline bulk loading terminals, grain elevators or coal processing where atmosphere may contain hazardous gases or dust.