Specifying intrinsically safe mobile devices: an ATEX / IECEx field guide.
A practical reference for buyers, system integrators and safety officers who have to tell a genuinely certified Ex device from one that only looks the part. Written for field use, not for a compliance exam.
Most sites that need a rugged handheld also need it to survive a dusty yard or a hose-down. A smaller set of sites need something stricter: a device that will not be the spark that ignites the atmosphere around it. Those two needs are covered by two completely different marks on the label, and mixing them up is the single most common reason an order gets rejected at the gate — or worse, accepted and then found non-compliant during an audit.
This guide separates the terms, shows how to read an Ex marking line by line, lists the markings that mean nothing, and gives a five-step check you can run before the purchase order is raised.
"Rugged" protects the device. "Ex" protects the site.
An IP rating (IP68, IP69K) says how well the device keeps water and dust out of itself. It says nothing about whether the device can be the ignition source in a flammable atmosphere. Explosion protection is a separate, certificate-based discipline.
Ingress protection
Defends the device against rain, spray, dust and immersion. Needed everywhere outdoors and in wash-down areas. Never a substitute for Ex certification in a classified zone.
Explosion protection
Issued by a notified body for a specific model and build. Permits the device to enter a classified area (Zone 1/2 gas, Zone 21/22 dust). The zone and gas/dust group must be covered by the marking.
Same box, different permission
A device can be IP69K and still be banned from a Zone 1 pump house. A device can be Ex-certified and still need a separate rugged case for a drop onto concrete. The two are bought and checked separately.
Four certificate schemes you will meet
Which one a project accepts is decided by the site's HSE team and the local authority — not by the datasheet. Specifying the wrong scheme is a silent failure: the device ships, then fails acceptance.
European Union — Directive 2014/34/EU
Mandatory for equipment placed on the EU market for explosive atmospheres. Certificates are issued by EU notified bodies and listed in the NANDO database. Recognised across the EEA and widely accepted elsewhere.
International — IEC system
The international scheme built on IEC 60079. A single IECEx certificate eases acceptance in Australia, New Zealand, and many Middle Eastern, African and Asian markets. Verifiable in the public IECEx database.
GB/T 3836 — China Ex
China's national standard, aligned with IEC 60079 but a separate certificate issued by CNEX, NEPSI or similar bodies. Accepted inside China and case-by-case in parts of Asia and the Middle East. Not automatic in the EU or North America.
North America — Class / Division
The US and Canada use Classes and Divisions (or Zones) under NEC Article 500/505. Acceptance requires local listing (e.g. FM, CSA). An ATEX or IECEx mark alone will not clear a North American site.
What the zone actually tells you
A zone describes how often a flammable atmosphere is present. The Equipment Protection Level (EPL) on the marking must match the zone. A device rated for Zone 2 may not enter Zone 1.
Zone 0 / 1 / 2
Zone 0: explosive gas present continuously. Zone 1: present in normal operation. Zone 2: present only in abnormal conditions. EPL Ga / Gb / Gc respectively.
Zone 20 / 21 / 22
Combustible dust, classified the same way by likelihood. EPL Da / Db / Dc. Most handhelds are gas-only (no dust marking) and must not enter a grain, flour or powder area.
How to read an Ex marking — line by line
A real marking is a structured code, not a word. Take a typical gas-Group-IIB/IIc device:
II 2 G Ex ib IIC T4 Gb
· Certificate No. XYZ 21 ATEX 0024
· Notified body: NB 2161
· Ta -20 °C ≤ T ≤ +60 °C
- II — equipment group for surface industries (mining is I).
- 2 G — category 2, gas atmosphere → Zone 1 capable.
- Ex ib — "ib" is intrinsic safety (energy-limited); "db" would be flameproof, "px" pressurized.
- IIC — gas group; IIC covers the most demanding gases (hydrogen, acetylene). IIB is narrower.
- T4 — temperature class; surface stays below 135 °C. Must exceed the auto-ignition of the gas present.
- Gb — EPL Gb, suitable for Zone 1.
Every one of those tokens should be traceable to a certificate number and a notified body. If the label shows "Ex" in a logo but none of this structure, it is not a certificate — it is decoration.
The markings that mean nothing
This is where projects go wrong. The right-hand column is what we are asked to "match" at least once a week.
REAL Certified, verifiable
- A full Ex marking with category, protection method, gas/dust group and temperature class.
- A certificate number and a named notified body (NB number).
- The certificate is listed in NANDO (ATEX) or the IECEx public database.
- The exact model and configuration (radio, scanner, camera) is named on the certificate.
- The certificate holder and the device brand are consistent, or a legal relationship is declared.
FAKE / VOID Looks the part, is not
- A menu or web page that says "ATEX" with no marking and no certificate number.
- An IP68 / IP69K rating presented as if it were explosion protection.
- A marking photo copied from another model or another brand.
- "Ex-style", "explosion-proof design" or "ATEX-ready" — marketing, not certification.
- A certificate whose model, option set or holder does not match the unit being quoted.
Five steps, before the PO
- Get the area classification. Zone (0/1/2 or 20/21/22), gas or dust group, and temperature class — from the site drawing, not from memory.
- Confirm the accepted scheme. ATEX, IECEx, GB, or North American listing. The project's HSE decides; the datasheet does not.
- Ask for the certificate, not the brochure. A PDF issued by a notified body, naming the exact model and build.
- Check it in the public database. NANDO for ATEX, IECEx Online for IECEx. The certificate number and body should resolve.
- Confirm the configuration is covered. If you need DMR, a scanner or thermal, the certificate must list that option — otherwise that build is not certified.
When the wrong tier is specified
The cost is not the device — it is the project.
Rejected at the gate
A device without the right certificate is turned away at site induction. The crew waits, the schedule slips, and a rush replacement costs more than the saving.
Non-compliance finding
If a "fake Ex" device is found in a Zone 1 area during an audit, the site can be shut down and the responsible parties liable. The badge on the box does not help.
Cover questioned
An incident in a classified area involving a non-certified device is exactly the scenario insurers examine first. The certificate is the evidence.
Send the area classification, not the model number.
Tell us the zone, the gas or dust group and the certificate the project accepts. We return the models that are actually allowed in — and flag, in writing, the ones that only look certified.