[ATEX · REAL WORLD]
This is for anyone who’s ever had ATEX requirements dropped on them late in a job and been told it’ll “only take five minutes”.
Summary
- Most ATEX issues aren’t caused by difficult calculations, they usually come from bad assumptions and missing information.
- The biggest problems start early. wrong zones, unclear data, or people relying on “what we normally use”.
- A calculation can be technically right and still cause problems if nobody else can follow it later.
- Common issues: overcomplicating things, poor starting assumptions, missing documentation, and fitting it in along side other work.
- A simple, repeatable approach is usually better than trying to fix things later when someone questions it.
ATEX – The Mistakes I Keep Seeing
Most of the ATEX problems I come across aren’t because someone doesn’t understand it.
They’re usually because something wasn’t clear at the start, or because people had to fill in the gaps themselves.
And that’s where it starts to drift.
What makes ATEX mistakes awkward: they don’t always show up straight away. They tend to come back during reviews, commissioning, or handover, when it’s a lot harder to explain or change anything. It could be an instrument that is Ex d going to an intrinsically safe barrier, it is a pain to fix, especially on site.
It can cost time, money and reputation with the client.
Intrinsically Safe Calculations are typically wrong due to missing information. It could be certificates for the devices that are non-exist ant or out of date. Converting units from specified values to another unit, like nano to micro.
ATEX Work Gets Treated Like a Side Task
Let’s be clear here, it shouldn’t be a side task. It is important to get it right. I think it is because it goes unseen. If you install a cable, the client see’s progress. If you confirm device ATEX requirements, it is a background thing.
ATEX ends up being something that gets picked up late, once everything else is already moving.
- zone gets assumed rather than confirmed
- gas group is taken from something similar
- temperature class gets picked because “that’s what we usually use”
ATEX doesn’t tolerate vague inputs very well.
Where It Goes Wrong (In Real Life)
Mistake #1 – Starting With the Wrong Assumptions
This is the main one.
If the starting point is off, everything built on top of it can look fine when it is not.
Typical things I see:
- zone not properly confirmed (lack of HAC Drawing)
- gas group copied from old info
- temperature class based on habit instead of actual data
Consequence:
- equipment gets selected on the wrong basis
- review turns into a back-and-forth
- someone ends up rechecking work that should have been solid
If the information is available from the start, this step becomes a lot easier.
Mistake #2 – Making It More Complicated Than It Needs to Be
There’s a tendency to complicate the requirements. Sometimes to try to save effort and money. Often the availability is an issue with bespoke, ATEX rated parts.
Most of the time it comes down to:
- zone
- gas group
- temperature class
- equipment suitability
Consequence:
- time gets wasted
- simple decisions become harder
- the end result is harder to review, not easier
If the basics are right, you’re most of the way there.
Mistake #3 – Output That Nobody Else Can Follow
This is the one that causes the most hassle later.
The work might be correct, but it’s not laid out in a way that anyone else can quickly understand.
Consequence:
- people start asking questions
- you have to explain what should already be obvious
- confidence in the work drops, even if it’s actually fine
If someone has to ask “how did you get that?”, the format is part of the problem.
Mistake #4 – Doing It Manually Every Time
This is where time disappears.
You end up:
- rewriting the same structure again and again
- double-checking things that shouldn’t need double-checking
- formatting outputs so they look presentable
Consequence:
- inconsistent results between jobs
- more room for small mistakes
- more time spent on formatting than actual thinking
I ended up putting together a simple tool just to keep things consistent and save time on this side of it.
You can use it here:
Mistake #5 – Leaving Documentation Until the End
This happens all the time.
The technical side gets done, and the documentation gets left until later. Usually the case with all documentation, not just with ATEX. When everyone just wants to get the job over the line, the documentation lags behind.
That’s when things get missed:
- assumptions aren’t written down
- inputs aren’t clear
- the final decision isn’t properly explained
Consequence:
- the same questions come back later
- someone has to dig back through the work
- it ends up taking longer than doing it properly the first time
Good documentation doesn’t make the decision better, it just stops it becoming a problem later.
The Bigger Issue: Missing Information
This is usually what sits underneath everything else.
People are asked to do ATEX-related work without being given:
- confirmed zone details
- reliable gas information
- clear temperature assumptions
- proper context of how the equipment is actually used
Imagine going shopping in the supermarket with the lights off. How do you know what your buying? If the inputs aren’t clear, the output won’t be either.
At that point, people start filling in gaps and ATEX doesn’t respond well to guesswork.
A Quick Note on Tools
Tools like the one on this site are useful for keeping things structured and avoiding obvious mistakes.
They don’t fix missing information.
If the assumptions are wrong, the output will still be wrong, just formatted better.
What To Do Instead
Most of the problems above aren’t technical. They’re just things not being nailed down early enough.
I’ve put together a short ATEX checklist based on the issues I keep seeing.
- Starting point: confirm zone, gas group, and temperature properly.
- Structure: make sure the logic is clear, not just the result.
- Documentation: write down the basis, not just the answer.
- Review: make it easy for someone else to follow.
- Consistency: don’t reinvent the format every time.
£9 · PDF · 7 pages
Download the ATEX checklist (coming soon)
Provided for guidance only — not a substitute for formal design review or site-specific engineering approval.
Final Thought
Most ATEX issues aren’t caused by the requirements being difficult to understand.
They’re usually caused by things not being clear early enough, or not being presented properly later.
It can be tricky but it does help if done properly a bit earlier.
If you’ve seen this kind of thing before, feel free to send it to the person who says the ATEX part can be “done later”.
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