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[ The PC Guide | Systems and Components Reference Guide | Power | The Power Supply | Power Supply Specifications and Certifications ]


Virtually all power supplies have their safety and quality certified by one or more agencies. These certifications indicate that the power supply has been tested and passed a certain standard. The more certifications a power supply possesses, the more it has been tested and the more standards it meets. Different certification bodies will focus on different types of testing. Most testing of relevance to power supplies relates to safety and general quality. Other tests deal with assessing how much electromagnetic interference (EMI) or radio frequency interference (RFI) the power supply generates.

Safety and quality certification is probably the most important thing to look for. There are many different companies that do certification in different countries. Normally, the power supply manufacturer will just list the acronym of each organization that has approved the device, or the acronym of the organization's approval "mark". Here are the most common ones you will see:

  • UL: Underwriters Laboratories, Inc. UL approval is "the" standard for safety and quality certification in the U.S.A.
  • CSA: CSA International (formerly the Canadian Standards Association). The Canadian equivalent of the UL.
  • NEMKO, TUV and VDE: NEMKO, in Norway, and TUV and VDE in Germany, are the organizations that do most of the electrical component certifications within Europe.
  • CE: Indicates that the product has been given the "CE mark", certifying that it meets the standards required to allow it to be sold within the European Community.

EMI/RFI compliance rules are established in the United States by the Federal Communications Commission (FCC). You will see many companies advertise that their power supplies are "FCC Class B certified". This is really not quite accurate, because the FCC does not certify individual power supplies, only systems. So what the manufacturer is claiming, at best, is that their power supply was certified as part of at least one type of system. This is still good to know of course. In practice, reputable power supply manufacturers will test their units with a wide variety of configurations.

Finally, some power supplies are Energy Star certified. This is an EPA program established to help promote energy-efficient PCs and components. The program is voluntary, but energy star certification is seen by many as reflective of the quality of the power supply, as well as environmental conscientiousness on the part of the manufacturer. Modern form factor specifications will detail the requirements of the form factor for the power supply to achieve energy star compliance.

The lack of certification of a device does not mean necessarily that it is a bad product. It does, however, mean that the product hasn't been thoroughly tested to meet the regular standards in the industry. There could be many different reasons why this is the case, but in my opinion, it's not really worth speculating over--I would simply avoid supplies that are not listed by at least one, and preferably several, of the better-known safety and quality certification bureaus.

Next: Motherboard and System Devices (Reference Guide)

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