Explosion-Proof Lighting

Explosion-proof lighting is a category of lighting fixtures designed to protect against the ignition of various environmental factors by uncontained sparks. Explosion-proof designs separate the internal electrical reactions of a light fixture from external fumes or hazardous materials.

This precaution is required within many contained environments where flammable gases, chemicals, or other ignitable atmospheric hazards exist. Explosion-proof lighting is required to comply with National Electrical Code (NEC) in many facilities. Before commissioning explosion-proof lighting solutions, it’s important to understand the technology and various options to ensure appropriate selection.

"Explosion-Proof" and "Hazardous Areas" Defined

The term "explosion-proof" often causes some confusion. Rather than resisting damage from explosions, explosion-proof lighting fixtures protect against external explosions by insulating lighting equipment from hazardous surroundings.

A standard light fixture can't fully contain all the sparks or heat generated inside. While these sparks are acceptable in some circumstances, they can cause ignition and explosions when they interact with hazardous elements in the atmosphere. Explosion-proof lighting fixtures are carefully designed to counteract this danger by safely containing any internal sparks or chemical reactions, preventing ignition in the surrounding environment.

Explosion-proof fixtures encase the light fixture in a thick frame made of a metal, such as steel or aluminum. A durable casing and shatter-resistant tempered glass lenses are used to balance durability with visibility. In most cases, these casings are also equipped with thermal control mechanisms.

At Papailias, this method of construction grants our explosion-proof fixtures several key benefits:


Our fixtures are designed to hold up to even the toughest industrial environments. These lights withstand vibration and standard wear, increasing their working life when compared to similar products. This extended lifespan reduces unnecessary downtime and saves money on maintenance, repairs, and replacements.


It is sometimes necessary to move lighting fixtures as conditions warrant. The sturdy construction of explosion-proof lighting ensures that it will resist damage from being relocated, whereas standard lights have a higher risk of breaking or otherwise malfunctioning.


For operations interested in efficiency, many modern explosion-proof lighting employs LEDs as a light source, which provides energy efficiency. LED lights produce equal lumens to standard solutions with a fraction of the required wattage. Compared to standard lighting fixtures, you can expect sizable decreases in energy expenditure.

Various regulatory bodies have developed more specific definitions for explosion-proof, including the National Electrical Manufacturers Association (NEMA), NEC, Occupational Safety and Health Administration (OSHA), and the National Fire Protection Association (NFPA). To be certified as explosion-proof through these bodies, a lighting solution needs to pass tests proving it complies with rigorous safety and performance requirements.

What Are Hazardous Areas?

Explosion-proof lighting is necessary in hazardous areas. In general, a hazardous area is one that contains each of the three necessary components for an explosion:

  • A flammable substance, which can be a variety of substances, such as chemical fumes, wood shavings, grain dust, or combustible gases
  • Oxygen, without which a fire is impossible
  • An ignition source, which can be as minimal as a spark

When these three factors combine, they may result in a catastrophic explosion. Accordingly, managers of facilities that handle flammable materials must take appropriate precautions to protect workers and safeguard their products.

The Zone and Group System for Hazardous Areas

The NEC outlines different designations that can be used to classify explosion risk in industrial settings. Assessing an operating environment in terms of the NEC's zones, groups, and classes is essential to ensure that your lighting fixtures comply with all regulations.

Zones categorize operating conditions by both the nature of hazardous material present as well as the probability of it being present for a prolonged period. For gases, vapors, and mists, the general breakdown looks like this, as defined in article 505 of the NEC:

  • Zone 0: Substances are present constantly, or for prolonged periods, in high enough concentrations to cause an explosion.
  • Zone 1: Substances can occur under normal operating conditions in high enough concentrations to cause an explosion.
  • Zone 2: Substances rarely occur in concentrations high enough to cause an explosion, and they are only present for a short period.

Article 506 translates these same standards for dusts, fibers, and flyings:

  • Zone 20: Substances are present constantly, or for prolonged periods, in high enough concentrations to cause an explosion.
  • Zone 21: Substances can occur under normal operating conditions in high enough concentrations to cause an explosion.
  • Zone 22: Substances rarely occur in concentrations high enough to cause an explosion, and they are only present for a short period.

Groups add specificity to zone classifications based on the type of hazardous material. Some groups are further broken down based on the surrounding atmosphere.

  • Group I: A mining region containing naturally occurring, flammable gases
  • Group II: Surrounding atmosphere contains explosive gases (further subdivided into A, B, and C based on the type of gases present)
  • Group III: Surrounding atmosphere contains explosive dusts (further subdivided into A, B, and C based on the type of dust present)

Explosion-Proof Lighting Requirements and Classifications

NEC and NFPA explosion-proof classifications define the standards for light fixtures to be rated as explosion-proof. The certification standards vary based on the environment's hazard level as defined by classes. These classes are comparable to zones and can be further qualified with groups.

Class I

Class I regions are defined by a high explosion risk due to flammable or combustible gases or liquids. The category is further broken down into the following groups:

  • Group A: Acetylene
  • Group B: Hydrogen
  • Group C: Propane and Ethylene
  • Group D: Benzene, Butane, Methane, Propane

Class II

Class II regions contain combustible dust or fibers:

  • Group E: Metal Dust
  • Group F: Carbon and Charcoal
  • Group G: Flour, Starch, Wood, and Plastic

Class III

Class III regions are specifically limited to cotton fibers and sawdust.


Divisions bring these classifications closer in line with the zone/group system by defining how likely the hazard is to be present.

  • Division 1: The hazardous materials are likely to be present. They are present continuously or frequently under normal operating conditions.
  • Division 2: The hazardous materials are unlikely to be present and are present only for a short time under abnormal conditions.

Applying These Requirements to Lighting Products

It's important to understand how your working environment is classified to ensure that you purchase lights that are compliant with all applicable regulations. For instance, if your operating environment always contains metal dust but no other hazards, you would need to purchase lights that are certified for Class II, Group E, Division 1 environments. Many Papailias products would be suitable, including the SLEX-HI-LED-00 and 01 and all of the SLEX/SVTC series lights, among others.

Explosion-Proof Lighting Products by Papailias, Inc.

Papailias offers four categories of explosion-proof lighting options to protect your facility and employees. All products are fully compliant with regulations for the classifications listed, offering you an assurance that you're purchasing only the most effective fixtures for your industry.

Halogen Hazardous Location Lights

These UL-844 & C-UL/CSA C22.2 listed halogen lamps provide high-intensity, glare-free lighting through a single port. These fixtures are energy-efficient and offer an extended lifespan compared to competing halogens. Specific options in our catalog include:

  • SLEX-100-00
  • SLEX-100-01
  • SLEX-100-03
  • REX-100-00
  • REX-100-01
  • REX-100-02
  • REX-100-03

High Intensity LED [HI-LED] Hazardous Location Lights

Our HI-LED SLEX and REX product lines combine all of the benefits of our halogen lamps with the longer lifespan afforded by a high-quality LED bulb. They also bring further energy savings over halogen options.

  • SLEX-HI-LED-00
  • SLEX-HI-LED-01
  • REX-HI-LED-00
  • REX-HI-LED-01

Sanitary High Intensity LED [HI-LED] Hazardous Location Light Glasses

With the SLEX/SVTC and REX/SVTC series sanitary glasses, you receive a highly functional, attractive lighting fixture with an integrated clamp-type sanitary lens. These fixtures provide an ideal solution for hazardous pharmaceutical environments and can withstand high temperatures and pressure ratings.

  • REX-HI-LED-00/3"SVTC
  • REX-HI-LED-01/3"SVTC
  • REX-HI-LED-01/4"SVTC

Sanitary High Intensity LED [HI-LED] Non-Hazardous Location Light Glasses

Our final category of light glasses is highly similar to the hazardous location line of sanitary light glasses, but these are specifically designed for industrial environments. You'll still receive the same durable construction, energy savings, and clear sightlines that are found in Papailias products.

  • REX-HI-LED-00/3"SVTC
  • REX-HI-LED-01/3"SVTC
  • REX-HI-LED-00/4"SVTC
  • REX-HI-LED-01/4"SVTC

Trust Papailias For Explosion-Proof Solutions

Explosion-proof lighting is not just advantageous, it's essential and required in many settings. Ensure that your supplier can adhere to all regulations while providing a cost-effective custom solution.

Papailias develops innovative solutions to industrial safety concerns, and our NEMA 4, NEMA 4X, and NEMA 7 enclosures ensure that explosion-proof lighting fixtures mitigate any risk of explosion in sensitive environments. To learn more about our expertise in this area, browse our lighting offerings or contact us with specific questions.