Explosion Proof Lighting refers to lighting fixtures that are able to contain sparks that could potentially ignite the flammable and explosive gases in the atmosphere. Explosion-proof lights are designed to be used in a “Hazardous Location”.
Broadly speaking, a hazardous location is an area where there are high enough concentrations of combustible materials in the air to cause a fire or explosion. This could be in the form of a gas (e.g. natural gas, ethanol, toluene, etc), a dust (e.g. grain, flour, coal, etc), or even a fibre. When these hazards are present, workers need to (by law) use specially designed equipment to reduce the risk of igniting the flammable materials lest they cause a catastrophic fire or explosion.
Hazardous location, need a light that can reduce and minimize the chance of igniting the gases (or dusts, depending on the location). This light can come in two basic configurations, explosion-proof or intrinsically safe.