NEC Article 500

Self Luminous Exit Signs for Hazardous Locations

Our customers continue to rave over our self luminous exit sign fixtures because of their amazing versatility. SL sign design doesn't vary much between models because there is no need to improve on perfection. They're like the classic VW Bug - they just keep running, don't make a fuss and can even go in the water!


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The National Electric Code (NEC) has classified certain industrial locations as hazardous "where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings."

These hazard classifications are defined in NEC Article 500, as well as 504, 510 through 517. However, Article 500 is most commonly referenced. You will notice this on most cut-sheets and product specs under the 'Code Compliance' listings for our self powered exit signs.

NEC Hazardous Location Classifications

Self luminous exit signs can be placed in any location deemed explosion hazard under the NEC.

NEC 500 codifies such locations in three ways:

  1. Type
  2. Condition
  3. Nature

For a more detailed overview, check out OSHA's NEC 500 page. If you're not sure if your facility qualifies as a hazardous location, contact our sales team. You can also call us at 800-379-1129 for a faster response.


There are three classes for the danger level posed in a given hazardous location.

Class I Locations: (most hazardous) a facility or space that produces flammable gases or vapors, which linger in the atmosphere in such quantities to cause an explosion. Even the smallest naked flame, or electric spark from an electronic exit sign, can spark an explosion in these places.

Class II Locations: (medium hazard) location that produces combustible dust that hangs in the atmosphere.

Class III Locations: (least hazardous) location which produces easily-ignitable fibers or flyings.


This signifies the likelihood of the hazard classes listed above being present in the given space.

Division 1 - hazards present during normal conditions.

Division 2 - hazards are not present unless under abnormal circumstances (such as an accidental spill).


Commonly called 'groups', where a Roman letter represents the type of hazardous substance present for each class and division.

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Class I

A: Acetone

B: Hydrogen, etc.

C: Ether, etc.

D: Hydrocarbons, fuels, solvents, etc.

Class II

E: Metal dusts

F: Carbon dusts

G: Flour, starch, grain, plastics.

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