Testing Lab of Power Supply/ IT / AV Products

CE certification for open frame power supplies — PCB-mount and chassis-mount power modules supplied without enclosures — presents unique compliance challenges due to their nature as incomplete components destined for integration into finished equipment. Unlike enclosed power supplies that can be CE marked independently, open frame PSUs must be evaluated in the context of their intended end-use installation. EMC and safety testing is conducted with the power supply mounted in a representative host enclosure, and the resulting test data supports the OEM equipment manufacturer's overall CE conformity assessment. This guide provides a framework for open frame power supply CE compliance, covering the regulatory context, representative host enclosure testing methodology, critical safety distance verification, and practical strategies for supplying compliance data that enables efficient downstream OEM certification.

Regulatory Context and Representative Host Testing

Open frame power supplies are classified as components under EU CE marking regulations. While they can undergo conformity assessment against the applicable directives — typically the EMC Directive (2014/30/EU) and Low Voltage Directive (2014/35/EU) — the assessment must be conducted with the PSU installed in a representative host enclosure. The concept of "reference installation conditions" is central: the PSU manufacturer defines a representative host enclosure (material, dimensions, ventilation, grounding scheme) and performs testing in that configuration. The test report documents these reference conditions, and downstream OEM integrators rely on this data as evidence contributing to their end-product CE conformity assessment.

EMC testing of open frame PSUs in a host enclosure faces two practical challenges. First, radiated emissions must be measured from the complete assembly — the enclosure's shielding effectiveness, ventilation opening pattern, and cable entry/exit points all influence the measured emission levels. Second, the enclosure material choice (metal vs. plastic) affects both shielding and grounding — a PSU tested in a metal chassis may show significantly different emissions than the same PSU in a plastic enclosure. The PSU manufacturer's test report should clearly document the reference enclosure specifications so that OEM integrators can assess compatibility with their own enclosure design. Open frame PSU reference host CE testing conducted with multiple representative enclosure types provides the most versatile compliance data for downstream integrators.

Safety Assessment and OEM Integration Compliance Strategy

LVD safety assessment per EN 62368-1 for open frame PSUs focuses on the inherent safety of the power supply design: insulation coordination (creepage and clearance distances on the PCB), transformer construction and insulation, and protection against electric shock from accessible terminals. The critical departure from enclosed PSU certification is that the "accessible parts" determination depends on the host enclosure — exposed terminals that would be accessible in the open-frame state are assumed to be protected by the host equipment's enclosure. The open frame PSU's insulation barriers must be evaluated at the PCB level, but the overall safety assessment presumes that the host enclosure provides the final layer of protection against user contact.

For OEM equipment manufacturers integrating open frame PSUs, the compliance workflow is: obtain the PSU manufacturer's CE test reports and Declaration of Incorporation; verify that the host enclosure design is consistent with the reference installation conditions in the PSU test report; perform host-level EMC verification (typically a radiated emission scan of the complete equipment); and reference the PSU's LVD test data in the host equipment's safety technical file. Open frame PSU OEM integration CE compliance support from the PSU manufacturer facilitates efficient end-product certification for downstream customers.

Frequently Asked Questions

This content is provided for industry communication and informational reference only and does not constitute any form of certification commitment, testing advice, or legal opinion. The certification requirements, procedures, and standards referenced herein may change as regulations evolve — please refer to the latest official announcements from the relevant authorities. Specific certification requirements, timelines, and costs must be evaluated by professional engineers based on the actual product. For inquiries, please contact us by phone.

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