CE marking for control panels and machines: the integrator's guide

There's a misunderstanding about CE marking that we see repeated among integrators with twenty years of experience: "every component in the panel has CE, so the panel has CE."

No. The CE marking on each component covers that component, under the conditions its manufacturer declared. The assembly you built — the control panel, the machine — is a new product, and the party responsible for making it comply with the directives that apply is whoever places it on the market or puts it into service: you, with your signature on the declaration of conformity.

Understood correctly, this isn't scary — it's a competitive edge. The integrator who delivers assemblies with their technical file in order closes deals that others lose the day the end client — or their auditor — asks for the paperwork. In this guide we lay out the whole subject: which directives apply, what the technical file contains, when you need a lab, what to ask each supplier, and the mistakes that invalidate the most declarations.

An honest disclaimer before we start: this is technical orientation from a manufacturer, not legal advice. For edge cases — and CE marking has plenty — the reference is the text of the directives, their official application guides, and, where appropriate, a notified body.

Note for readers outside Europe: CE marking applies to placing products on the European market. If you're building for North America, the equivalent framework is UL/CSA certification — see the certification note further down for what that means for PLCs specifically.

Component vs. assembly: why your panel is a new product

The logic of CE marking is one of cascading responsibility. The power supply manufacturer guarantees that their supply complies. The PLC manufacturer, that their PLC complies. But nobody has evaluated the combination you assembled: your layout, your wiring, your clearances, your ventilation, your loads. That evaluation is yours.

From that, two practical rules follow:

1. The components' CE marks are your foundation, not your roof. They save you from testing what their manufacturers already tested — provided there's real documentation behind them (more on this below).
2. What you add — assembly, wiring, integration — is exactly what you need to be able to justify.

Which directives apply to your assembly

For the vast majority of panels and machines with a PLC, the map looks like this:

Three notes that clear up frequent confusion:

• Low Voltage (2014/35/EU): covers the electrical safety of the assembly (shock, fire, overheating). For panels, the usual path is the EN 61439 series, which defines design verifications and individual verifications for each panel manufactured.
• EMC (2014/30/EU): your assembly must not emit interference above the limit, nor be disturbed by interference from its environment. In an industrial environment, the generic standards are EN 61000-6-4 (emission) and EN 61000-6-2 (immunity). This is the directive that fails the most assemblies — we'll see why below.
• Machinery (2006/42/EC): applies when you deliver a complete machine (or partly completed machinery), and absorbs the Low Voltage safety objectives for the electrical part, which is resolved per EN 60204-1. It requires documented risk assessment. Watch the calendar: Machinery Regulation (EU) 2023/1230 replaces the directive and becomes mandatory from January 20, 2027 — if you sell machines, you need to plan for that transition now.

The technical file: what it is and what it must contain

The technical file is the folder that demonstrates, with evidence, that your assembly complies. It isn't submitted to anyone by default: it is kept, available to market surveillance authorities (typically for 10 years from the date the product was placed on the market). The reasonable minimum contents for a control panel or control machine:

1. General product description: what it is, what it does, where it's installed, unique identification (model, serial number).
2. Complete electrical schematics and panel layout drawings, as actually built — not as designed three revisions ago.
3. List of critical components with their declarations of conformity and datasheets: power supply, PLC, protection devices, drives, safety elements.
4. Risk assessment (mandatory under the Machinery Directive; good practice always): hazards identified, measures taken, residual risks. Your program's safe-states document is naturally part of this.
5. List of applied standards and justification of how each requirement was verified: calculations, EN 61439 design verifications, applied EMC installation rules, in-house or lab test reports.
6. Instruction manual and usage information: installation, environmental conditions, maintenance, warnings.
7. The EU declaration of conformity: the one-page document stating which directives and standards the product complies with, signed by an authorized person.

The golden rule: the file gets built while the assembly is being built. Reconstructing it afterward is more expensive, slower, and usually uncovers the problem we discuss at the end.

Where things actually go wrong: EMC

Electrical safety rarely fails — electricians have it in their blood. Where assemblies fall down is electromagnetic compatibility, almost always for one of these three reasons:

1. The drive that skipped its homework

Drives installed without their line filter, without shielded motor cable, or with the shield not connected 360° at both ends. It's the number one emission source in a typical panel — and the irony is that the drive manufacturer explains exactly how to install it in the EMC chapter of the manual, which is the chapter nobody reads. If your assembly has a drive, that chapter is part of your file: apply it and document that you applied it.

2. Components with "decorative" CE

Cheap power supplies and peripherals whose CE letters have never seen a lab. This is where the responsibility cascade breaks: you integrate, you sign, you answer for it. A critical component with no real conformity documentation isn't a saving — it's a hole in your technical file, and often also the noise source that will fail your emission test.

3. The wiring undoes what the design achieved

You can assemble an entire panel with excellent components and ruin the EMC with the wiring: shields left unconnected (or connected without a plan), signal cables run parallel to power cables, no equipotential bonding, filters installed far from the cable entry point. An assembly's EMC is built through the panel's layout — it isn't bought along with the components.

Do you need a lab and a notified body?

It depends on what you're delivering — and this is the part that's most reassuring once you understand it:

• Typical control panel (Low Voltage + EMC): the conformity assessment is done by the assembly manufacturer itself (self-certification). With well-documented components, properly applied EMC installation rules, and a solid file backing it up, in many cases you don't need an external lab. Lab testing becomes strongly advisable when you're manufacturing in series (the cost gets diluted and the risk multiplies), when you're integrating strong emission sources (drives, radio frequency), or when your documentary justification would be weaker than a test report.
• Complete machine: also self-certification in most cases, with a file and risk assessment. The exception is machines in the especially hazardous categories (Annex IV of the directive: presses, injection molding machines, safety devices...), where involving a notified body may be mandatory. If your machine is or might be on that list, don't settle it by reading a blog post — not even this one: consult the notified body before designing, not after.

What to ask each component supplier, exactly

When buying each critical component, request and file it at the time of purchase (not when you need it):

• EU declaration of conformity for the component, citing directives and standards.
• Datasheet with conditions of use: temperature range, installation category, mounting requirements.
• EMC-relevant installation instructions when the component requires them (drives, switched-mode power supplies, filters).
• For safety components: certificate from the relevant body and reliability data (PL/SIL) if applicable.

A serious supplier hands this over without hesitation. A supplier who can't hand it over is telling you something important about their CE marking. At Industrial Shields, the documentation for every PLC is available so that part of your file is covered: the range carries CE marking (with a published CE test report), the M-Duino 21+, 42+ and 58+ models additionally hold ETL certification from Intertek to UL 61010 (UL Std. 61010-1 and 61010-2-201, and CSA C22.2 No. 61010-1) for the North American market, and every product in the shop offers its declarations of conformity and downloadable certificates on its own page.

The documentation mistake that invalidates the most declarations

We promised to answer this, and here it is: the declaration of conformity that cites standards the file doesn't back up.

It's the most common failure, and the quietest one. The declaration states "compliant with EN 61439-1, EN 61000-6-2, EN 61000-6-4"... and the file contains no evidence those standards were actually applied: no design verifications, no documented installation rules, no tests, no technical justification. Sometimes with aggravating factors: standard revisions withdrawn years ago, or standards copied from another product's declaration that has nothing to do with this one.

In an inspection or a claim, that piece of paper doesn't protect you — it points at you. A declaration is only as valid as the evidence behind it. The check we recommend before signing any declaration: go through the cited standards one by one and ask "what document in the file proves this?" If any standard goes unanswered, either generate the evidence or remove it from the declaration.

In summary

1. The components' CE doesn't mark your assembly: the assembly is a new product, and the responsibility is yours.
2. Typical panel: Low Voltage + EMC. Complete machine: Machinery + EMC (and watch for Regulation 2023/1230 from January 2027).
3. The technical file gets built while you assemble, not afterward.
4. EMC is won or lost in three places: the drive, components with no real documentation, and the wiring.
5. Self-certification is viable in most cases; a notified body is needed when the machine falls into the Annex IV categories — and when in doubt, ask.
6. Never sign a declaration that cites standards with no evidence in the file.

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And if you're choosing the controller for your next panel: every Industrial Shields PLC publishes its technical documentation and downloadable certificates on its product page — for example, the M-Duino 21+ lists its datasheets, User Guide and 3 certifications: https://www.industrialshields.com/shop/is-mduino-21-m-duino-ethernet-plc-arduino-21-3670. Full detail on the ETL/UL 61010 certification for the M-Duino 21+, 42+ and 58+ is here: https://www.industrialshields.com/blog/arduino-raspberry-pi-industrial-news-industry-4-0-iot-11/etl-certification-for-an-open-source-based-industrial-plc-209