Safety Certification for Power Management Products
By Jerry Hoopes
Performed by an OSHA-certified testing laboratory, safety certification is an independent evaluation and test for product safety per the safety standards applicable for the product category. Laboratories certified by OSHA for safety testing are referred to as nationally recognized testing laboratories (NRTL). Products that have successfully passed the testing by the NRTL are authorized to bear the mark of the laboratory. With this mark, the buyer of the product can be assured that the product has been independently tested for safety.
Just as the products are subject to evaluation by the NRTL, the NRTL itself is subject to audit. OSHA audits the laboratories by several criteria, including consistency of processes and procedures, adequacy and training of staff, the accuracy of measurements and test environment, and traceability of test results and documentation. One of the most important requirements for the NRTL is continuous validation of certified products in production, where a representative of the NRTL visits the factory location to ensure that the product being manufactured is the same as what was tested.
In the U.S., there is no law that requires products to be certified for safety prior to sale. However, in order for an electronic device to be used in the workplace, OSHA requires it to be certified for safety by an NRTL. In any case, it only makes sense to practice the due diligence of verifying the safety of the products sold to your customers. Certification also offers some protection against liabilities, as it shows that the expense and effort was put forth to verify that the products are safe. However, if contested in a court of law, not having safety certification could be considered as indicia of negligence.
In North America, the two most widely known NRTLs are Underwriters Laboratories (UL) in the U.S., and the Canadian Standards Association (CSA) in Canada. Both laboratories have been certified by the respective governing bodies to perform safety certification testing for both countries. For example, a product with the cULus mark has been tested by UL for use in both the U.S. and Canada. The "C" in front of the mark indicates compliance to Canadian requirements, and "US" for the United States. Alternatively, a product with the cCSAus mark has likewise been tested by CSA. Most NRTLs follow the same convention to indicate compliance to both countries.
In the U.S., UL has been operating for over 100 years, and due to its familiarity, there is often a misconception that it is part of the government. It is not. UL drafts many of the safety standards for the U.S., which are then used by all NRTLs. Separate agencies such as CSA, TÜV, and ETL all test to the same standards as UL. Any one of these agency markings is a valid assurance that the product has been exposed to a vigorous testing and certification process."
A safety standard is a document that applies to a specific category of product. It outlines the criteria for terminology, materials, construction, testing, and markings as they pertain to product safety. It is important to know that a safety standard does not include tests for performance. Just because a product bears the mark of a NRTL does not necessarily mean that it is a quality product, just a safe one. However, it is not uncommon to see that some of the safety specifications that are required to be marked on the product are used for marketing purposes.
Power management products are tested under standard UL 1363 – Re-locatable Power Taps, which applies to products that extend power to multiple outlets as an extension of the branch circuit. In addition, devices whose function is to suppress surge energy to AC loads are tested under standard UL 1449 – Transient Voltage Surge Suppressors. Most power management solutions are sold as power taps and surge protectors, so they have to meet the requirements of both standards.
In addition to UL1449 and UL1363, power management products are also subject to several other standards, including:
- UL 498 – Attachment Plugs and Receptacles
- UL1283 – Electromagnetic Interference (EMI) Filters
- CSA C22.2 No. 21 – Cord Sets and Power Supply Cords
- CSA C22.2 No. 0.4 – Grounding and Bonding
- CSA C22.2 No. 8 – Electromagnetic Interference (EMI) Filters
There are several advantages to using more than one NRTL. For example, Panamax/Furman certifies products with UL, the Canadian Standards Association (CSA), Intertek (ETL), and TUV. The company uses more than one lab for two main reasons. First, certain key customers require certification from a specific lab. For example, a Canadian customer would prefer a CSA mark, while a U.S. customer might prefer a UL mark. The second reason concerns project completion time. In most projects, safety certification is the last activity of the product development process and is almost always on the critical path. Test labs can have very long project queues. In that case, the decision is often made to use a lab that can get the project through the process more quickly.
Safety certification is an important qualification for any power management solution. When selecting a product for any application, the presence of an NRTL mark should be a determining factor. This mark can be from UL or any other of the many certified laboratories. Without it, the manufacturer either has not made the effort to make its product safe, or the product did not meet safety standards when tested. In either case, it is a clear indicator that the product does not belong in your application.
UL Standards Technical Panel
Standards Technical Panel
About the Author
Jerry Hoopes has been with Panamax and now Core Brands since 1992 and serves as Core Brands Director of Hardware Engineering since 1998. He has also been a voting member of the UL 1449 Standards Technical Panel (STP) since 2003. The STP is a group of industry representatives that drafts the content of the UL 1449 standard. Jerry may be reached at firstname.lastname@example.org.