Explosion Proof Lighting Blog | Guides & Technical Articles

By SEEKINGLED Engineering Team · September 2026 · 8 min read

An ATEX certificate is only as good as the marking behind it. This guide decodes the full Ex marking string on a luminaire, explains how equipment categories map to zones, and sets out what a buyer should cross-check before releasing payment.

ATEX in One Paragraph

"ATEX" comes from the French ATmosphères EXplosibles. Luminaires sold for explosive atmospheres in the EU are placed on the market under Directive 2014/34/EU, and three things travel together: the hexagonal Ex mark and CE marking on the body, an EU declaration of conformity referencing the certificate number, and — for Category 1 and 2 equipment — an independent certificate covering the design.

Equipment Categories Map to Zones

Category	Marking suffix	Zones	Certification requirement
1	Ga / Da	0, 1, 2 / 20-22	Notified body certificate + QA
2	Gb / Db	1, 2 / 21-22	Notified body certificate
3	Gc / Dc	2 / 22	Internal control or notified body

For lighting, most real-world demand is Category 2 (Zone 1, Ex db/eb Gb) and Category 3 (Zone 2, Ex nR Gc). The "X" suffix on a certificate number means special conditions apply — read them; they often concern mounting orientation or torque values on cable glands.

Decoding the Full Marking String

Take this real-world example from a Zone 2 LED flood light:

Ex nR IIC T6 Gc

Element	Meaning
Ex	Explosion-protected equipment
nR	Non-sparking with restricted breathing enclosure
IIC	Gas group IIC — covers hydrogen/acetylene, the most demanding (IIA and IIB are subsets)
T6	Max surface temperature 85°C
Gc	Gas environment, Category 3 → Zone 2 only

A Zone 1 flameproof equivalent would read Ex db IIB T5 Gb. Note what changes and what doesn't: the protection method and category move with the zone; the gas group and T-class move with the process fluid, not the zone.

Certificate Portfolio: A Real Example

A credible manufacturer publishes its certificate map across product families. SEEKINGLED's current portfolio (EX Catalog, September 2026):

Series	Product	Protection	Zones	ATEX certificate
FL8	LED flood light	Ex nR IIC T6/T5 Gc	2 / 22	TÜV CY 26 ATEX 0207611 X
GS	Petrol station canopy light	Ex nR IIC T6/T5 Gc	2 / 22	TÜV CY 26 ATEX 0207612 X
LU	Linear light	Ex nR IIC T6 Gc	2 / 22	TÜV CY 26 ATEX 0207613 X
LO	Linear light	Ex db IIB T6 Gb	1 / 21	CSANe 25 ATEX 1229X + IECEx CSA 25.0093X
FL7	LED flood light	Ex db IIB T6 Gb	1 / 21	Flameproof range for Zone 1
HB21	LED high bay	Ex db IIC T6/T5 Gb	1 / 21	Flameproof range for Zone 1

This spread illustrates a procurement principle: one manufacturer, two certification tiers — flameproof (Zone 1) and restricted-breathing (Zone 2) — lets a project source both categories from a single supplier with consistent spares.

The LO linear series carries both marks — see its ATEX & IECEx certified linear light specifications.

Checking a Certificate Before You Pay

A certificate PDF is a starting point, not proof. What decides whether a quotation is backed by real certification is whether the marking on the product, the certificate and the quotation all describe the same thing. The checks below do most of the work, and none of them depend on the supplier's cooperation.

Step 1: Decode the marking on the fixture

Start on the product, not on the paper. Every certified luminaire carries a permanently marked string on the body. If the marking is missing, unreadable or applied on a sticker that peels off, stop there — that alone is a non-compliance.

Component	Example	What it tells you
Equipment group	II	Surface industry (I is mining only). Luminaires for refineries, chemical plants and fuel depots are group II.
Category	2	Category 2 = usable in Zone 1 with a certified protection method. Category 3 = Zone 2 only.
Atmosphere	G / D	G = explosive gas atmosphere, D = combustible dust. Both letters on one fixture means dual gas and dust certification.
Protection type	db	db = flameproof enclosure. Other common types on luminaires: eb (increased safety), nR (restricted breathing, Zone 2), tb / tc (dust enclosure protection).
Gas group	IIB / IIC	IIB covers ethylene-class gases; IIC covers hydrogen and acetylene — the most demanding group.
Temperature class	T6	Maximum surface temperature: T6 = 85 °C, T5 = 100 °C, T4 = 135 °C. The class must sit below the ignition temperature of the surrounding gas.
Equipment protection level	Gb / Gc	Gb = high protection, suitable for Zone 1. Gc = enhanced protection, Zone 2. Db / Dc are the dust equivalents.

A full string such as II 2 G Ex db IIC T6 Gb therefore reads: surface industry, category 2, gas, flameproof enclosure, hydrogen-class gas group, 85 °C maximum surface temperature, Zone 1 capable. Cross-read the same string against your area classification before the order goes out — a Category 3G fixture specified into a Zone 1 area is a non-compliant installation, regardless of how genuine its certificate is.

Step 2: Cross-check three things against the certificate

Check	What a pass looks like
Model designation	The exact model and power rating you are ordering appears in the certificate scope — not just the family name.
Certificate holder	The certificate is held by the entity you are buying from, not by an unrelated factory the seller cannot name.
Marking consistency	The Ex string on the certificate matches the nameplate and the datasheet — gas group, temperature class and equipment protection level all line up.

These three checks catch the two most common problems in Ex procurement: a certificate that belongs to a factory the seller has no relationship with, and a genuine certificate stretched to cover a model or power rating outside its scope.

Eight red flags of a counterfeit, stale or misused certificate

Red flag	What it usually means
The certificate is only ever shown as a photograph of a nameplate	Nameplate photos are not certificates. A genuine supplier sends the certificate PDF on request, without hesitation.
The model designation on the certificate does not match the quotation character for character	Common with trading companies routing a certificate from a different product, or from a discontinued revision.
The certificate covers only part of the power range you are ordering	Scope limits are normal (a certificate may cover 50–150 W of a series only). Ordering 300 W on a 150 W certificate is buying uncertified equipment.
The certificate holder cannot be confirmed by the issuing body	The certification cannot be traced to the entity actually named on it.
The certificate number returns nothing when the issuing body is asked directly	Either it never existed, or it has been superseded and the supplier is quoting an old document.
An "X" certificate without the special conditions of use	The document is genuine but incomplete — installation conditions are a mandatory part of it.
The document is a test report or a voluntary certification mark, not an EU-Type Examination Certificate	Test reports are useful evidence, and voluntary marks are worth having, but neither is a conformity assessment certificate under the directive. If the route requires a notified body, only the certificate discharges that requirement.
The certificate relies on harmonised standards withdrawn years ago, with no gap analysis offered	An older certificate can still be formally valid, but the manufacturer must show that the safety requirements have not changed. A supplier who cannot explain the standards position has not looked at it.

What to request from a supplier before you pay

Five documents, all of which a genuine manufacturer releases on request. Our own paperwork for every series is collected in our document library.

Document	Why you need it
ATEX and/or IECEx certificate PDF (not a photo)	Contains the exact model designations, power range, protection types, gas group, temperature class and any X conditions.
Production-phase approval and its number	Shows the factory — not just the design — is approved to keep producing certified equipment.
EU Declaration of Conformity	The manufacturer's signed legal statement of compliance under Directive 2014/34/EU — a separate obligation from the certificate itself.
Product datasheet for the quoted model	Lets you verify that the specification offered matches the specification certified — the two are not automatically the same document.
Installation and maintenance instructions	Mandatory for compliant installation, and particularly for X certificates where special conditions govern the mounting, cable entries or environment.

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