EMC Directive FAQ Failed EMC Tests

The EMC Directive requires equipment to meet the essential requirements in Annex I. For apparatus, conformity assessment must demonstrate that generated electromagnetic disturbance does not exceed the level above which radio, telecommunications, or other equipment cannot operate as intended, and that the apparatus has adequate immunity for its intended use.

A failed emission or immunity test therefore means the tested configuration has not demonstrated the relevant part of the essential requirements. It may still be possible to show conformity after redesign, a justified technical change, a corrected installation condition, a different representative configuration, or a properly documented standards route, but the failed result must be addressed rather than buried.

Treat a post-market failure as a conformity investigation, not only a laboratory task. Determine which models, revisions, batches, configurations, accessories, and Member State markets may be affected. A failed sample does not by itself establish that every unit is non-compliant, but the manufacturer cannot ignore evidence that apparatus it placed on the market may no longer conform.

If the manufacturer considers or has reason to believe that apparatus it placed on the market is not in conformity, Article 7 requires immediate corrective measures to bring it into conformity, withdraw it, or recall it if appropriate. Where the apparatus presents a risk, the manufacturer must inform the competent national authorities in the Member States where it made the apparatus available and give details of the non-compliance and corrective measures. Importers have parallel duties for apparatus they placed on the market.

Start with a controlled failure record, not a rewritten pass narrative. Preserve the failed test report, lab observations, plots, limits, setup photos, operating modes, cable routing, auxiliary equipment, and deviations from the planned test method. Then identify whether the failure is caused by the product design, the representative configuration, production variation, installation conditions, or an incorrect standard or test setup.

Remediation should be technical enough to explain why the corrected configuration now meets the relevant phenomenon. Typical records include changes to filtering, shielding, source support, PCB layout, enclosure bonding, firmware operating modes, clocking, cable selection, power supply, installation instructions, or component specification. If the product is a fixed installation issue rather than apparatus, document the good engineering practice and component intended-use information that support the installation correction.

Update the technical documentation before release. The record should show the failed result, what changed, why the change addresses the emission or immunity issue, what standard or technical specification now supports the claim, and whether the change affects other Union legislation listed on the same EU declaration of conformity.

For harmonised standards, check that the reference is one published for the EMC Directive and that the product still falls within the standard's scope, limits, test methods, and Annex ZZ mapping. If a standard was superseded, part-applied, or deviated from, record the date and scope of the standard used, the parts applied, the deviation, and the additional evidence used to cover the essential requirements. Do not sign or update the EU declaration of conformity for the affected model until the evidence supports the statement that the essential requirements have been demonstrated.

The retest should prove the same risk has been closed, not merely that a different sample passed a different setup. Match the retest to the failed phenomenon, the corrected configuration, and the intended operating conditions. Where the apparatus has multiple representative configurations, retain the rationale for the worst-case configuration and explain why untested configurations remain covered.

Keep the retest package readable for a market-surveillance request: final sample identification, version-controlled design changes, test plan, lab report, applied standards and dates, deviations or alternative specifications, photographs or diagrams of the setup, measured results against limits or criteria, and an approval note that connects the retest to the EU declaration of conformity.