Where must the Ex marking be, and must it stay visible after installation?

The manufacturer must put the Ex marking on the main part of the equipment, legibly and indelibly, and in a place where it can be read from the outside. Standards do not forbid every installation in which a nameplate ends up hard to see, but the marking is what installers, inspectors and maintainers check against, so in practice it must stay readable, or at least accessible, for the life of the equipment. Warning markings that the operator must act on have to be placed where the operator will see them after installation.

Short answer

• Manufacturer's duty: mark the main part of the equipment, legibly and durably. Under ATEX the marking must be legible and indelible; IEC 60079-0 (2017 edition) requires it to be visible from the exterior.
• Small and very small items: reduced marking is allowed when space is limited. Where there is no practical space, the full marking may come on a label to be fixed next to the equipment.
• Packaging only in exceptional cases: the ATEX Guidelines accept marking on packaging and documents only where the product's size or nature makes marking it impossible, never for appearance.
• Installer's duty in practice: do not paint over, cover or remove nameplates. Where the plate will be hidden (for example inside a cabinet), make sure it can be reached for inspection and record the marking in the equipment register.
• Operator warnings: an IECEx decision says that where the operator must take action after installation, the warning must be in a location likely to be visible to the operator.

What the standards and the directive say about location

IEC 60079-0, the general requirements standard, has long required the marking to be on the main part of the equipment. The public 2004 edition puts it simply: legibly marked on the main part. Later editions, as quoted in IECEx committee papers on the 2017 text, add that the marking must be visible from the exterior. The rule targets the main part because covers, glands and accessories can be swapped. A marking on a detachable cover could end up on the wrong enclosure.

The same standard allows concessions for size:

On the legal side, Directive 2014/34/EU requires equipment and protective systems to be marked legibly and indelibly with the minimum particulars of Annex II 1.0.5. The European Commission's ATEX Guidelines (6th edition, January 2026) add practical points:

• the CE marking must be visible, legible and indelible, and at least 5 mm high, except on small products;
• moving the marking to the packaging is acceptable only when the product's size or nature makes marking it impossible, and never purely for appearance;
• in an assembly, the CE markings of built-in sub-assemblies may not be visible after construction. That is acceptable because the information is available elsewhere, but the final product must carry a single label relating to the final assembly.

Must it stay visible after installation?

The installation and inspection standards depend on the marking. IEC 60079-17 inspection schedules start with checks that the equipment suits the EPL or zone, the equipment group and the temperature class, and that circuit identification is correct and available. Those checks are normally made against the nameplate and the records. IEC 60079-14 (2024) requires installation documentation that includes information on the Ex equipment, and makes initial inspection part of the installation.

So the practical rule is:

1. Install so the nameplate can be read without dismantling, where the layout allows: orient the equipment, choose the mounting side, keep plates clear of insulation, sun shields and cable bundles.
2. Where it will be hidden, for example a component inside a larger enclosure or a motor behind a guard, record the full marking and certificate in the equipment register and make sure an inspector can reach the plate when needed.
3. Never paint over or coat a nameplate, and do not remove it during maintenance. A plate made unreadable by paint, corrosion or dust is an inspection defect; a published study of Ex d and Ex e inspections shows a painted-over label plate as a typical finding.
4. Keep warning labels where they work. IECEx decision sheet DS 2017/006, on electrostatic warning markings, says that where the operator must act after installation to keep the equipment safe, the marking must be likely to be visible to the operator. Where the operator interacts with the equipment, it must be near the surface concerned.

Common mistakes

• Fitting the marking to a removable cover or a separate tag during repair. It belongs on the main part.
• Painting nameplates together with the enclosure.
• Hiding plates behind lagging or sunshades with no record of what they say.
• Treating the marking on the box as sufficient for an extremely small item. If the manufacturer supplied a label, it must be installed next to the item.

Related on excodex

• How to read an Ex marking: decoding II 2 G Ex db IIC T4 Gb step by step
• Ex installation basics under IEC 60079-14
• What if the Ex nameplate is missing or unreadable?
• What should I do if the nameplate marking differs from the Ex certificate?
• Tool: Ex marking check

Standards and further reading

• IEC 60079-0, general requirements: location of marking, reduced marking for small and extremely small equipment (edition 8, 2026); paraphrased from the public 2004 edition: law.resource.org (PDF)
• IECEx, compilation of comments on a draft decision sheet on marking of Ex components, quoting the 2017 marking clause: iecex.com
• IECEx decision sheet DS 2017/006, location of the electrostatic discharge hazard warning: iecex.com
• European Commission, ATEX 2014/34/EU Guidelines, 6th edition (January 2026), CE marking, marking of small products and of assemblies: single-market-economy.ec.europa.eu (PDF)
• IEC 60079-17, inspection schedules (items as reproduced in Moldovan et al., Annals of the University of Petrosani, Electrical Engineering 23, 2021): upet.ro (PDF)
• IEC 60079-14:2024, documentation and initial inspection (contents in the preview): standards.iteh.ai (PDF)

This article is general technical information prepared by the excodex editorial team. It does not replace the applicable standards, the equipment certificates and instructions, national regulations or the assessment of a competent person.