Lighting

Suggest you check your local electric code for this answer.

hingorani1971,

Of course 'necessary' is relative to your local code requirements, but I think you are more trying to understand why flameproof fixtures would be required in a humid environment.

Dusts being explosive is of course the root cause, but humidity alone does not remove the threat since it may not be universally or evenly distributed. CJM

It depends on the hazardous area zone classification of the areas of the plant the lights will be placed in. If the area is not a hazardous area (now more commonly called flammable atmosphere area) then the fitting needs to just be rated for the environment (such as having the appropriate IP 'Ingress Protection' rating).

This answer is a very general one given the information you have given. Can you please provide more information.

It is necessary to use hazardous-area-rated equipment, to the relevant section of the applicable code for the hazardous area zone, wherever a potentially explosive atmosphere exists.