ATEX Marking Requirements
Every piece of ATEX-certified equipment must carry specific markings that identify it as suitable for use in explosive atmospheres. These markings aren't just regulatory formality—they're the primary tool that installers, inspectors, and end-users rely on to confirm that the right equipment is installed in the right zones. Getting marking wrong, or failing to understand what the marking means, is one of the most common causes of compliance failures in the field.
CE Marking and the Notified Body Number
The CE marking is mandatory for all ATEX equipment placed on the EU market. It's the manufacturer's declaration that the product meets all applicable EU requirements—not just ATEX, but any other directive that applies (such as the Low Voltage Directive or Machinery Directive). The marking must be visible, legible, and permanent.
If a notified body was involved in the production-phase assessment—which is required for Category 1 and usually Category 2 equipment—its four-digit identification number appears immediately after the CE marking. For example, "CE 0123" tells you that notified body number 0123 supervised production quality. Category 3 equipment assessed under Module A (self-certification) won't have a notified body number after the CE mark.
The ATEX-Specific Marking
Alongside the CE marking, every piece of ATEX equipment displays explosion protection marking that tells you where the equipment can safely be used. The EC ATEX Guidelines (§144-153) describe the marking system in detail. The key elements are:
- The hexagonal Ex symbol ⟨Ex⟩: This distinctive symbol immediately identifies the equipment as designed for explosive atmospheres. It's specified in the directive itself and must appear on all ATEX-certified products.
- Equipment group: I for mining, II for surface industries.
- Equipment category: M1 or M2 for mining; 1, 2, or 3 for surface industries. The category directly indicates the protection level and determines which zones the equipment is suitable for.
- Atmosphere type: G for gas/vapour/mist, D for dust, or both G D if certified for both environments.
For example, the marking "II 2 G" means Group II (surface industries), Category 2 (suitable for Zone 1 and Zone 2), for gas atmospheres.
Product Standard Marking
Beyond the directive-level marking, equipment for gas atmospheres carries additional marking from the product standards (principally EN/IEC 60079-0). This includes the specific protection type code (Ex d, Ex e, Ex i, etc.), the gas group (IIA, IIB, or IIC), and the temperature class (T1-T6) or maximum surface temperature. Modern marking also includes the Equipment Protection Level (EPL)—Ga, Gb, or Gc for gases, Da, Db, or Dc for dusts.
A complete marking string might look like: CE 0123 ⟨Ex⟩ II 2 G Ex db IIC T4 Gb. Every element tells the user something specific about where and how the equipment can be safely used. For a step-by-step walkthrough, see our guide on reading ATEX labels.
General Identification Marking
In addition to the explosion protection marking, each product must display the manufacturer's name or registered trademark, the product type or model designation, and any serial, batch, or type number needed for traceability. The manufacturer's postal address must also be available, either on the product or in the accompanying documentation.
The X and U Suffixes
Two suffixes on ATEX certificates and markings require special attention. An "X" suffix on the certificate number means "specific conditions of use"—the equipment has limitations or installation requirements beyond what's obvious from the standard marking. These might include restrictions on ambient temperature range, requirements for specific cable types, or mandatory additional protection measures. Before installing X-marked equipment, you must read the certificate or manufacturer's instructions to understand these conditions. Ignoring them invalidates the certification.
A "U" suffix identifies an Ex component—a product designed to be incorporated into other equipment, not installed standalone in a hazardous area. U-marked items do not carry the CE marking (for ATEX purposes) and must never be installed directly in a classified zone without being part of a complete, certified assembly.
Marking Durability
The EC ATEX Guidelines emphasise that marking must remain legible throughout the equipment's expected life. Engraving or embossing is preferred over adhesive labels in harsh environments. Where labels are used, they must withstand the environmental conditions—UV exposure, chemical contact, abrasion, temperature extremes. Equipment found during inspection with illegible marking requires remarking or replacement, as inspectors cannot verify suitability if they can't read the label.