A Guide to Power Supply Safety Standards in Japan

Ensuring the safety of electrical equipment is mandated by law. In Japan, the Electrical Appliance and Material Safety Act (DENAN) governs these requirements to prevent hazards and ensure product safety.

Manufacturers and importers must perform conformity assessments to prove compliance. The Act categorizes regulated items into two groups:

• Specified Electrical Appliances and Materials (Category A): 116 items deemed to strictly require regulation due to higher risk, such as cables, fuses, and heating appliances. These require a diamond-shaped PSE mark.
• Non-Specified Electrical Appliances and Materials (Category B):341 items, including electric heaters and light sources, which require a circle-shaped PSE mark.

Note on DC Power Supplies: While "DC power supply units" are listed as Specified Electrical Appliances, this classification primarily targets consumer-grade AC adapters. Industrial power supplies designed for use within factories or embedded in other machinery generally fall outside the scope of the consumer PSE mark requirements, though they are still engineered to meet rigorous safety standards.

Products compliant with the Act must display the PSE mark (Product Safety, Electrical appliance & materials). The technical requirements for PSE are harmonized with international standards, specifically IEC standards.

The relevant IEC standards depend on the application:

• IEC 62368-1: Audio/video, information, and communication technology equipment.
• IEC 61010-1: Safety requirements for electrical equipment for measurement, control, and laboratory use.

When exporting or operating electrical equipment globally, products must comply with the safety standards of the destination country. Most national standards are harmonized with IEC 62368-1 and IEC 61010-1.

Key regional standards include:

• USA: UL 62368-1, UL 61010-1
• Canada: CSA C22.2 No. 62368-1, CSA C22.2 No. 61010-1
• EU: EN 62368-1, EN 61010-1

Manufacturers must verify the specific regulatory requirements for each target market, as deviations from the IEC base standards may exist.

Safety testing verifies that equipment is designed to prevent electric shock, fire, and secondary damage during operation or failure. These tests are conducted according to international (IEC) or national standards.

Common safety tests include:

• Dielectric Withstand Voltage Test (Hipot Test): Verifies insulation integrity under high voltage.
• Leakage Current Test: Ensures current flowing to the ground or chassis is within safe limits.
• Insulation Resistance Test: Measures the resistance of insulating materials.
• Ground Continuity Test: Confirms the integrity of the protective earth connection.

In addition to safety, equipment is tested for EMC (Electromagnetic Compatibility), which ensures devices operate correctly in their electromagnetic environment.

EMC consists of two main components:

• EMI (Electromagnetic Interference): Ensures the product does not emit excessive noise that could disrupt other equipment.
• EMS (Electromagnetic Susceptibility/Immunity): Ensures the product does not malfunction when exposed to external electromagnetic noise.