From the Desk of Lewis Bass

Welcome back to “Ask Lewis Bass,” our ongoing series where we answer real-world questions from engineers, compliance teams, and safety professionals working on the safety compliance aspects of their engineering projects.

Question:

Hi Lewis Bass,

We’re working on a CE marking project for a piece of industrial equipment that was originally built for another client of ours in the EU. We’ve modified a few components: mainly the control system and we also added a safety interlock. We’re planning to ship this redesigned system to our new customer in the EU this quarter.

Do we need to start the CE marking process from scratch, or can we leverage the original design and documentation?

– Bill W. 

Lewis Bass:

Hi Bill,

When you modify equipment for the European market, the first thing you need to understand is this: CE marking is tied to the final configuration of the machine, not its history.

That means even if your original system was well-designed, safe, and fully documented, any meaningful modification (like a new control system or added safety interlock) can trigger a fresh compliance evaluation.

And yes, that applies to your CE marking project.

But, first, what counts as a “significant change”?

This is where engineers tend to get stuck.

In your case, updating the control system and adding a safety interlock isn’t a cosmetic modification, it directly impacts how the machine operates and how risks are mitigated. From a CE perspective, that’s a big deal.

Changes like these can affect:

• Functional safety performance
• Risk reduction measures
• Electrical design and conformity
• Documentation requirements (especially your Technical File)

So even though you’re not starting from zero, you also can’t just “reuse” your old design and call it compliant.

Now, to your question about being able to potentially reuse existing documentation and the technical file from the prior CE project, well, a solid CE marking project doesn’t ignore prior work. Instead, it builds on it.

You can typically reuse:

• Existing schematics and BOMs (if still applicable)
• Mechanical design elements that haven’t changed
• Previously identified hazards and mitigation strategies

But, and this is critical, you need to re-validate everything against the current configuration.

Think of it like this: your original design is your foundation, but your modified machine is the structure inspectors will evaluate.

If you want to move efficiently (and avoid headaches), here’s the approach we recommend:

1. Start with your existing documentation as a baseline
2. Perform a fresh risk assessment on the modified system
3. Identify all applicable EU directives (Machinery Directive / Machinery Regulation, Low Voltage, EMC, etc.)
4. Update your Technical File to reflect the current design
5. Verify that all safety functions meet applicable standards (like EN ISO 13849 or IEC 62061, if relevant)

This keeps your CE marking project grounded in reality while still leveraging the work you’ve already done.

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