Components vs Equipment
The ATEX Equipment Directive (2014/34/EU) distinguishes between "equipment" and "components"—and the distinction matters for certification, marking, and how products can legally be used. Getting this classification wrong can mean either over-engineering simple parts or, worse, treating incomplete products as ready-to-install equipment. The EC ATEX Guidelines (§46-48) explain the distinction in detail.
The Key Distinction
According to Article 2 of the directive, components are items essential to the safe functioning of equipment and protective systems but with no autonomous function. Equipment, by contrast, can perform its intended function independently—it's complete and ready to use in a hazardous area.
The test is whether the product has "autonomous function." A product has autonomous function if it can safely deliver its intended purpose without needing additional parts. The fact that equipment requires installation, connection to a power supply, or following specific instructions doesn't remove autonomous function—those are normal conditions for any equipment. A flameproof junction box with terminals inside is equipment; the same enclosure sold empty (without terminals) is a component.
Common Examples of Components
Components typically include empty flameproof enclosures before electrical assemblies are fitted, certified terminal blocks designed for incorporation into Ex equipment, encapsulated relays with flying leads, certified cable glands, Zener barriers sold for incorporation into safety systems, display modules without standalone capability, and Ex-certified connectors or plugs meant for integration into larger assemblies.
Each of these items needs further work before it becomes usable Ex equipment. An empty enclosure isn't equipment until it contains the electrical assembly it's designed to house. A barrier isn't equipment until it's connected into a complete intrinsically safe circuit.
Conformity Assessment for Components
Components undergo conformity assessment using the same module structure as equipment—the same procedures apply based on the intended category. However, instead of receiving an EU Declaration of Conformity, components receive a "written attestation of conformity" that states their characteristics, the conditions under which they may be used, and instructions for how they must be incorporated into complete equipment.
Marking Rules
This is where the practical differences become most visible. Components must not bear the CE marking for ATEX purposes—even if they require CE marking under other directives (such as the Low Voltage Directive). They carry Ex marking showing their protection type and parameters, but the absence of the ATEX CE mark signals clearly that they're not complete products ready for the market as standalone items.
When you see a "U" suffix on ATEX marking (such as "Ex db IIC T6...U"), it identifies an Ex component. This U suffix signals that the product isn't intended for direct installation in a hazardous area—it must first be incorporated into complete equipment. Installing a U-marked component directly would be non-compliant and potentially dangerous.
Becoming the Manufacturer of an Assembly
When someone combines components—or components plus other parts—to create complete equipment, they take on manufacturer obligations for that assembly. They must ensure the complete assembly meets all applicable requirements, carry out or arrange the appropriate conformity assessment, issue the EU Declaration of Conformity, and apply CE and ATEX marking.
Using pre-certified components simplifies this process because the component's attestation provides assurance about that element's compliance. But the assembler still takes full responsibility for the complete product, including how components are integrated, any additional parts added, and the overall safety of the finished equipment.
Why the Distinction Matters in Practice
Confusion between equipment and components leads to real problems. Treating equipment as components means incomplete certification—the product might be sold without the protection it needs. Treating components as equipment means trying to install products that aren't ready for hazardous area use. During inspection, finding U-marked products installed directly in a classified zone is a compliance failure that must be addressed immediately. Notified bodies, manufacturers, and end-users all need to understand this distinction and act accordingly.
