Posted to News on 6th Oct 2026, 10:38
Five things to settle before a machine specification says ATEX
The word ATEX appears in more and more specifications for machines, panels and instruments. On its own it settles nothing. Between the end user who writes the specification and the engineer who has to meet it, five points need to be agreed before the word means anything.
1. Which zone, and who decides
ATEX is two European directives. One sets the requirements for equipment placed on the market, the other sets the duties of the employer at the workplace. Under the second, transposed in Great Britain as DSEAR, it is the employer who assesses the risk and classifies the places where an explosive atmosphere may occur into zones. A supplier cannot do that for a site it does not operate.
A specification that says "ATEX" without naming the zone therefore asks the supplier to guess. It should state the zones the equipment will be installed in or carried into, taken from the site's hazardous area classification, including the temporary zones that appear during cleaning and maintenance.
2. A category and a marking, not a word
Certified equipment carries a marking that states what it is made for: category 1, 2 or 3, corresponding to zones 0, 1 and 2 for gas and 20, 21 and 22 for dust, together with a gas or dust group and a temperature class. Equipment certified for zone 2 is certified, but it is not suitable for zone 1, however solid it looks. The specification should ask for the category, the group and the temperature class that the zone and the substances on site require, and the supplier should quote the marking in the offer.
3. The assembly, not only the components
A certified motor, a certified sensor and a certified junction box do not add up to a certified machine. Once components are combined, the assembly has to be assessed as a whole: interactions between parts, mechanical ignition sources such as hot bearings and friction, and the way the parts are installed. Who carries out that assessment, and who signs for it, is a point to agree at the start of the project rather than at the acceptance test.
4. What comes and goes
The machine is fixed. The people around it are not, and neither is what they carry. Commissioning laptops, portable instruments, inspection lamps, phones and tablets all enter the zone at some point, and each is subject to the same rule as the machine itself. A good specification says what may be used inside the zone during commissioning and maintenance, and where portable devices are charged, which is outside it.
5. Documents and the handover
Certificates, the specific conditions of use that come with an X after the certificate number, installation instructions and the list of approved accessories belong with the equipment for its whole life. Before a workplace with classified areas is used for the first time, its explosion safety has to be verified by a competent person, and any later modification to certified equipment can invalidate its certificate. Agreeing at the outset who keeps the file and who signs off changes saves the discussion later.
The word is a starting point
None of this is unusual engineering. It is the ordinary discipline of writing down what the equipment is for, in terms the standards recognise. For engineers who meet the term for the first time, ATEXshop's short introduction to what ATEX means is a useful place to start before the specification is written.
