A couple of years ago, I gave a class to some maintenance folks and one of the topics was what it meant when someone says, "Listed" or "Approved". When I research it for the class, I realized how little I knew about the subject. Spawned by a different post and just doing some product research to verify its listing, I thought I share a few thoughts.
Everything we do in this trade has a rule or regulation somewhere. The NEC says we must use listed or approve components. This is fine but how do you know what you are installing is listed or approved? Just because this is what you were taught is not a good enough answer.OSHA
oversee a program that regulates testing organizations such as Underwriter's Laboratory (UL) and Canadian Standards Association (CSA) just to name a couple. This program is called, "National Recognized Testing Laboratories”. I am not going to go into details on it but give you the Cliff Note version of it. You can go to OSHA’s web site which is actually user friendly and read about the NRTL
A NRTL recognized testing facility
tests certain products that are mandated by OSHA to be tested such as all electrical equipments and components. The manufacturer of a product takes their product to a NRTL lab and tells them that my product that will be used in a such and such manner and it meets or exceeds applicable approved standards
. The lab will then test the product for a fee to verify that the product meets the applicable standards. If the product meets the standards then the laboratory will license to the manufacturer the rights to print the lab’s stamp of approval only on that product. The testing lab’s job is not finished. They will continue to monitor and test the product over time to ensure the product still meets the necessary standards. The testing lab reserves the right to pull their licensing agreement if the product doesn’t meet the standards.
Each testing laboratory has a series of stamps that everyone may have seen from time to time. Each style of stamp has a certain meaning. UL for example, has several different types of stamps. “UL” or “C
” means that the product can be used in the U.S. providing is installed and will be used as it was intended for. If in the U.S. and you see, “C
UL”, it means that it only meets Canadian standards. It does not mean the product is inferior product. Canada and the U.S. have different standards and the product does not meet both standards. Improper installation, field modified, or improper use can void its listing and it can no longer be used. To learn more about the different stamps, you can go to the each lab’s web site to learn more about them.
A common problem in the manufacturer world is fake listed stamps. This can pose a serious risk of inferior product failing and cause death, injury, and lost of property. You, the electrician can be held accountable for using improper labeled products so you must CYA. For those of you who do not know CYA is, it means Cover Your Butt. It is all but impossible to ensure that each and every part is really listed. One thing I do is buy my critical parts through reputable distributors like distribution equipment and wire. The distributors can be liable too for an accident so they go extra mile to ensure their products are legitimately listed. BTW, I do not work for any distributor.
Another thing you can do is you can locate a product’s listing. Several of the testing labs provide product info online for free. You just need to know where to find the info you are looking for. For example, U.L. Online Certification Directory
has a versatile search engine. The problem is knowing what to type in. Some brand names buy another company’s product and put their brand name on it. The problem is you need to know the manufacturers’ name who holds the listing for it. There is other ways to find the products’ listing, you just need to know the proper terms. It varies from site to site.