Power supply safety certification is highly important and required by law in many countries. Agency and organizational markings tend to break down geographically. UL represents the United States, CSA represents Canada, TUV, Nemko and others represent Europe.
Each agency tries to promote its mark as a universal stamp, but due to local customs and laws, a power supply manufacturer typically obtains certification with a combination of UL, CSA and one or more European stamps. The agencies have agreements in place that allow multiple certifications within a single testing facility. Listed below are some of the common agencies and their safety marks.
Underwriters Laboratories Inc. (UL) is an independent, not-for-profit product-safety testing and certification organization. Primarily identified with the North American market, UL has tested products for public safety for more than a century. Computer power supplies should bear the UL mark for component parts, shown below are component marks for US, Canada, and combined US & Canada. Every North American computer power supply should have at least one of these marks. http://www.ul.com/
The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and United States. CSA Marks appear on over one billion products worldwide. Each mark tells you that an authorized testing laboratory has evaluated a sample of the product to determine that it meets applicable safety standards. http://www.csa.ca/
CE (for LVD)
The EU New Approach Directives make it mandatory for any company placing products onto the EU market to meet the legal requirements and affix a CE Mark on products to indicate this compliance. The CE marking indicates appropriate level of safety and quality for use in European markets. http://ec.europa.eu/enterprise/newapproach/
Established in 1933, Nemko's certification mark is mandatory for electrical products marketed in Norway. Since 1991, it is offered as a voluntary mark and has gained worldwide recognition as a sign of compliance with relevant safety and EMC standards within the IT and office equipment. http://www.nemko.com
The Nordic Certification Service, a long standing agreement between the EMKO bodies (Demko, Fimko, Nemko, Semko) as national certification bodies in Denmark, Finland, Norway and Sweden. The four marks (D)(FI)(N)(S) may be obtained by one single application and submittal. Due to the well known tradition for safety awareness in the Nordic countries, these marks on a product carries a strong message of safety.