Hazardous Location Lighting Classifications Explained: Class I vs Class II, Division 1 vs Division 2, and Groups
Explosion-proof and hazardous location lighting is a code-driven safety decision....
Learn More →ATEX Lighting Guide: Understanding Hazardous Location Zones vs Divisions
This guide explains how ATEX (ATmosphères EXplosibles) Zones work, how they differ from the National Electrical Code (NEC) Division system used under UL 844, and how to interpret common ATEX and IECEx markings when selecting explosion-proof lighting for international or multinational projects. This content is intended for educational reference only and does not replace site-specific hazardous area classification. ATEX and IECEx classifications are frequently misunderstood. While the NEC Class and Division system is standard in the United States and Canada, most industrial facilities outside North America rely on ATEX or IECEx Zone-based classifications to define hazardous or explosive atmospheres. This post talks specifically about how it applies to ATEX explosion proof lighting.
Who This ATEX Guide Is For
- Electrical engineers working on European Union (EU) or global industrial projects
- Facility managers responsible for hazardous location compliance
- OEMs and contractors sourcing explosion-proof lighting internationally
- North American teams translating NEC classifications into ATEX requirements
ATEX Lighting Guide: How ATEX Zones Differ from Divisions
Outside North America, hazardous locations are commonly specified using ATEX (the European Union legal framework) or IECEx, an international certification scheme. These systems use zone-based classifications that define the frequency and duration of explosive gas or dust presence in an environment and determine what level of equipment protection is required. UL provides a helpful overview of global hazardous location marking systems, including NEC, ATEX, and IECEx classifications: Global HazLoc and Explosive Atmosphere Markings (UL)
What Does ATEX Mean?
ATEX originates from the French phrase “ATmosphères EXplosibles.” It refers to two European Union directives governing worker safety and equipment used in explosive environments.
- Directive 2014/34/EU: Defines equipment and protective system requirements, ensuring products are designed for use in explosive environments.
- Directive 1999/92/EC: Establishes minimum workplace safety requirements for environments where explosive atmospheres may occur.
Certified ATEX lighting fixtures intended for explosive environments are evaluated to ensure they will not ignite explosive gases, vapors, or dust under both normal operating conditions and defined fault conditions.
ATEX Gas & Vapor Zone Classifications
| Zone 0 | Explosive gases or vapors are present continuously or for long periods. |
| Zone 1 | Explosive gases or vapors are likely to be present during normal operation. |
| Zone 2 | Explosive gases or vapors are not likely during normal operation. If they occur, they exist only for a short time. |
ATEX Dust & Powder Zone Classifications
| Zone 20 | Combustible dust or powder is present continuously or for long periods. |
| Zone 21 | Combustible dust or powder is likely to occur during normal operation. |
| Zone 22 | Combustible dust or powder is not likely during normal operation. |
UL 844 vs. ATEX vs. IECEx: Practical “Rule of Thumb” Mapping
Key takeaway: UL 844, ATEX, and IECEx systems are related but not interchangeable. The mapping below provides a general reference to help interpret terminology. Final fixture selection must match the site’s documented hazardous area classification and applicable regulatory requirements.
| Hazard Type | North America (NEC/CEC) | ATEX / IECEx (Zones) | Common Rule of Thumb |
| Gas / Vapor | Class I, Division 1 | Zone 0 / Zone 1 | Division 1 often aligns with Zone 1 and sometimes Zone 0 depending on continuous presence. |
| Gas / Vapor | Class I, Division 2 | Zone 2 | Division 2 is commonly treated as roughly comparable to Zone 2. |
| Combustible Dust | Class II, Division 1 | Zone 20 / Zone 21 | Division 1 often aligns with Zone 21 and sometimes Zone 20. |
| Combustible Dust | Class II, Division 2 | Zone 22 | Division 2 is commonly treated as roughly comparable to Zone 22. |
ATEX Categories and IECEx Equipment Protection Levels (EPL)
In the Zone system, equipment may be identified using ATEX Categories 1, 2, and 3 with the suffix G for gas or D for dust. IECEx uses Equipment Protection Levels (EPL) such as Ga, Gb, Gc, Da, Db, or Dc. IECEx certification is widely accepted outside the EU and commonly used for multinational industrial projects: IECEx Certification Overview (UL)
| Zone | ATEX Category | IECEx EPL | General Meaning |
| Zone 0 (Gas) | 1G | Ga | Very high protection; explosive gas present continuously. |
| Zone 1 (Gas) | 2G | Gb | High protection; explosive gas likely during normal operation. |
| Zone 2 (Gas) | 3G | Gc | Enhanced protection; explosive gas unlikely during normal operation. |
| Zone 20 (Dust) | 1D | Da | Very high protection; combustible dust present continuously. |
| Zone 21 (Dust) | 2D | Db | High protection; combustible dust likely during operation. |
| Zone 22 (Dust) | 3D | Dc | Enhanced protection; combustible dust unlikely during operation. |
“Ex” Markings Explained: Ex d, Ex e, Ex t, and More
ATEX and IECEx markings include protection concepts such as Ex d (flameproof enclosures), Ex e (increased safety), and Ex t (protection by enclosure for dust). These markings indicate how equipment is designed to prevent ignition and what operating conditions it can safely withstand. Bottom line: A fixture may be described as “explosion proof” in general language, but true compliance requires matching the correct Zone or Division, gas or dust group, temperature classification, and certification marking.
Common ATEX Classification Mistakes to Avoid
- Assuming Class I Division 1 automatically equals Zone 1
- Selecting ATEX equipment without confirming the correct Category or EPL
- Overlooking combustible dust hazards in facilities focused primarily on gas risks
- Using “explosion proof” as a generic term without verifying Ex certification markings
Important Safety & Compliance Notice
This guide is provided for general educational purposes only. ATEX and IECEx classifications must be determined by qualified professionals based on site-specific conditions, materials present, ventilation, and applicable regulations. Lighting manufacturers and suppliers do not assign ATEX Zones. Final fixture selection must comply with local laws, ATEX workplace directives, and the facility’s hazardous area classification documentation.
Need Help Matching ATEX Zones to the Right Fixture?
If you already have an ATEX Zone or IECEx EPL identified in your safety documentation and need help selecting compliant explosion-proof lighting, start here: Explosion Proof LED Lights
About The Author
Dwayne Kula - Founder, President & Chief Technology Officer, LED Lighting Supply
Dwayne Kula is the Founder, President, and Chief Technology Officer of LED Lighting Supply, a company he established in 2008 to help businesses adopt reliable, high-performance LED lighting solutions. With more than 17 years of experience working with LED technology and lighting systems, Dwayne has developed extensive expertise in LED fixtures, energy-efficient lighting design, and commercial and industrial lighting applications.
In his role, Dwayne evaluates lighting technologies, guides product selection, and leads the development of technical and educational content for the LED Lighting Supply website. A significant part of his work involves creating articles and resources that help facility managers, contractors, and engineers better understand LED lighting and make informed purchasing decisions. His hands-on industry experience and technical knowledge help ensure customers receive practical, trustworthy guidance when selecting LED lighting solutions.
