Testing Lab of Power Supply/ IT / AV Products

Scope: This article applies to AC-DC power adapters, switching power supplies, battery chargers, and power conversion equipment intended for the EU market, with operating voltage in the range of AC 50–1000V or DC 75–1500V.

1. CE Certification Framework: The Four Core Directives

CE marking is the manufacturer's declaration that a product complies with all applicable EU directives. For power products, compliance is not a single test but a multi-directive conformity assessment. The four directives most commonly involved are:

LVD (Low Voltage Directive) 2014/35/EU

Scope: Electrical equipment with operating voltage between AC 50–1000V or DC 75–1500V. Power adapters, chargers, and switching power supplies all fall within this range.

Objective: To prevent electrical shock, overheating, fire, and mechanical hazards under normal and single-fault conditions.

Primary standard: EN 62368-1:2018 (Audio/video, information and communication technology equipment safety).

EMC (Electromagnetic Compatibility) 2014/30/EU

Scope: All electrical/electronic equipment capable of generating or affected by electromagnetic disturbance.

Objective: Two-fold — (1) the device must not emit excessive electromagnetic interference (EMI); (2) the device must be able to operate correctly in its electromagnetic environment (EMS).

Primary standards: EN 55032 (emission), EN 55035 (immunity).

RoHS (Restriction of Hazardous Substances) 2011/65/EU

Scope: All electrical and electronic equipment. Restricts the use of lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE in homogeneous materials.

Primary standard: EN 50581 (technical documentation for RoHS compliance).

ErP (Eco-Design) 2009/125/EC

Scope: External power supplies (EPS) and energy-related products.

Requirement: Compliance with EU 2019/1782 (Code of Conduct V5 / DoE Level VI) for no-load power consumption and average active efficiency.

2. LVD Testing: Core Safety Test Items

LVD compliance is verified through a series of safety tests defined in EN 62368-1. The following are the core test items for power products:

Test Item	Purpose	Typical Criterion
Insulation Resistance Test	Verify basic and supplementary insulation integrity	> 2 MΩ (basic), > 5 MΩ (supplementary)
Dielectric Withstand Test (Hi-Pot)	Verify insulation can withstand transient overvoltage	3000V AC / 4242V DC, 60s, no breakdown
Leakage Current Test	Ensure touch current stays within safe limits	< 0.25 mA (handheld), < 3.5 mA (stationary)
Grounding Continuity Test	Verify protective earth connection reliability	< 0.1 Ω (low-resistance path)
Temperature Rise Test	Ensure components do not exceed safe temperature limits	Transformer < 150°C, enclosure < 60°C (touchable)
Abnormal Operation Test	Safety under fault conditions (short-circuit, locked rotor)	No fire, no electric shock hazard after fault applied
Flammability Test	Verify enclosure/material fire resistance	V-0 or V-1 rating per UL 94 / IEC 60695

Note: Test conditions and acceptance criteria vary by product class and end-use environment. Always refer to the latest edition of EN 62368-1 for precise values.

3. EMC Testing: Emission and Immunity

EMC testing is divided into two categories: Emission (the device must not interfere with others) and Immunity (the device must not be disrupted by external interference).

Emission Tests (EN 55032)

• Conducted Emission (150 kHz – 30 MHz)

• Radiated Emission (30 MHz – 6 GHz)

• Harmonic Current Emission (EN 61000-3-2)

• Voltage Fluctuation & Flicker (EN 61000-3-3)

Immunity Tests (EN 55035)

• Electrostatic Discharge (ESD, EN 61000-4-2)

• Radiated Immunity (EN 61000-4-3)

• EFT/Burst (EN 61000-4-4)

• Surge (EN 61000-4-5)

• Conducted Immunity (EN 61000-4-6)

For power adapters with output power ≤ 250W, Class B emission limits apply (more stringent than Class A). Testing should be performed in a qualified EMC laboratory with anechoic chamber or shielded room facilities.

4. Technical File: What You Must Prepare

The technical file (technical documentation) is the backbone of CE certification. EU regulations require manufacturers to retain the technical file for at least 10 years after the product is placed on the market. It must be made available to market surveillance authorities upon request.

A complete technical file typically includes:

① Product specification and user manual (with safety warnings)

② Circuit schematic diagram and PCB layout drawings

③ Bill of Materials (BOM) with component certifications (VDE, UL, CQC, etc.)

④ Mechanical drawings and exploded view

⑤ Risk assessment report (per EN 62368-1 Annex Q)

⑥ LVD test report (from accredited laboratory)

⑦ EMC test report (from accredited laboratory)

⑧ EU Declaration of Conformity (DoC) — signed and dated

5. EU Declaration of Conformity (DoC) and CE Marking

Once all tests are passed and the technical file is complete, the manufacturer (or authorized representative) signs the EU Declaration of Conformity (DoC). This is a legally binding document. The DoC must include:

• ▪Manufacturer name and full address
• ▪Product model name/number and description
• ▪List of applicable EU directives (e.g., LVD 2014/35/EU, EMC 2014/30/EU)
• ▪Standards applied (e.g., EN 62368-1:2018, EN 55032:2015)
• ▪Notified body information (if involved)
• ▪Place and date of issue, name and position of authorized signatory

After DoC is signed, the CE mark can be affixed to the product, packaging, and user manual. Requirements for CE marking:

• Minimum height: 5 mm

• Must be proportional (cannot stretch or distort the letters)

• Must be permanently affixed (printed, molded, or engraved — not a sticker that can be removed)

Important: If the manufacturer is not established in the EU, an EU Authorized Representative (EAR) must be appointed. The EAR's name and address may be required on the product label or packaging, depending on the specific directive.

Frequently Asked Questions

Q: Is there a "CE certificate" issued by an authority?

For LVD and EMC directives, there is no mandatory certificate issued by an authority. The manufacturer declares conformity by signing the DoC — this is a self-declaration model. However, third-party test reports from accredited laboratories are strongly recommended to demonstrate compliance and are often required by distributors, platforms (Amazon EU), and customs.

Q: Can I use CB test reports to speed up CE certification?

Yes. CB reports based on IEC 62368-1 are technically aligned with EN 62368-1. Having a CB report can significantly reduce duplicate LVD testing. However, EMC testing typically requires supplementary tests to EU-specific standards (e.g., EN 55032 emission limits may differ slightly from CISPR 32). It is advisable to involve a laboratory familiar with both CB and CE requirements early in the design phase.

Q: How long is a CE certification valid?

The test report itself has no fixed expiry date. However, if the product design, key components, or applicable standards change, a re-assessment is required. The DoC must be updated whenever there is a material change. Many EU customers request a fresh test report annually as part of supplier quality audits.

This article is generated with AI assistance. Content is for reference only and does not constitute any certification commitment or legal advice. Refer to the latest official EU regulations.

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