Modified products under the EMC Directive when reassessment is needed

Reassess the product when a change can affect the electromagnetic compatibility conclusion already documented for the apparatus. Examples include changes to circuit design, power supply, shielding, enclosure, source support, filters, ports, cables, installation conditions, firmware behavior that affects emissions or immunity, operating configuration, or the intended electromagnetic environment.

Directive 2014/30/EU requires manufacturers to take changes in apparatus design or characteristics, and changes in the harmonised standards or technical specifications used for the declaration, adequately into account. The EMC assessment must also cover normal intended operating conditions and the configurations the manufacturer identifies as representative of intended use.

If the existing assessment relied on harmonised standards, a standards change does not automatically require a complete retest. The Commission EMC Guide says the evaluation may be limited to modifications directly affecting the apparatus, but the manufacturer must evaluate whether the newer standard, clause, phenomenon, or scope change affects the product and may consider re-testing.

The original manufacturer remains responsible for apparatus it places on the market, including the conformity assessment, technical documentation, EU declaration of conformity, and CE marking. But the Directive also says an importer or distributor is treated as the manufacturer when it places apparatus on the market under its own name or trade mark, or modifies apparatus already placed on the market in a way that may affect compliance.

That matters for private-labeling, refurbishment, retrofit kits, field upgrades, local power-supply substitutions, enclosure changes, and software or accessory packages sold as a changed product. The company making or commissioning the compliance-affecting modification should not assume the original manufacturer, test lab, supplier, or notified body carries the updated conformity responsibility. A like-for-like repair does not automatically create a new product; the Blue Guide distinguishes ordinary repair or maintenance from an important change or overhaul that modifies original performance, purpose, or type.

Importers also have their own gatekeeping role: before placing apparatus on the market, they must ensure that the manufacturer carried out the appropriate conformity assessment, drew up technical documentation, applied CE marking, and supplied required documents. If the importer has reason to believe the modified apparatus does not conform, it must not place it on the market until it is brought into conformity.

If the modification is covered by the existing assessment, the record should show why. If the modification changes the assessed apparatus, the EU declaration of conformity may need to be updated so it identifies the modified apparatus, the applicable Union acts, the standards or technical specifications applied, and any notified-body certificate information where applicable.

The CE marking is not a substitute for the reassessment. CE marking is affixed after the applicable conformity assessment has been completed. If the change creates a new product or invalidates the existing assessment basis, the modifier must complete the relevant conformity work before placing the modified apparatus on the market with CE marking.

If the product used the EU-type examination route and there is an EU-type examination certificate, modifications to the approved type that may affect conformity or certificate validity must be reported to the notified body holding the technical documentation. The Directive requires additional approval as an addition to the original certificate for those modifications.

A useful modification record lets a market-surveillance authority, importer, distributor, or customer understand whether the existing CE-marked product evidence still applies. It should connect the physical change to the EMC phenomena, standards, test configurations, and DoC entries that were reviewed.

For targeted re-testing, the record should explain why the selected tests, clauses, frequency ranges, configurations, or engineering comparisons are enough. For no-test decisions, the Commission EMC Guide says technical documentation should include explanations demonstrating how the essential requirements are met when tests are not performed under the manufacturer's responsibility.

For fixed-installation-specific apparatus, do not mix the apparatus exemption into ordinary product sales. The EMC Guide describes that exemption as tied to a particular fixed installation and a direct link between the manufacturer of that apparatus and the responsible installation parties.