Looking Beyond NEMA and UL Markings When Specifying Enclosures

In the United States, we’re well aware of a number of marking schemes 
that indicate how products like enclosures will perform in particular 
settings. These will include the National Electrical Manufacturers 
Association (NEMA) rating indicating how resistant a product will be in 
various wet, dirty or corrosive locations. There might also be a UL 
marking indicating a standard to which the product has been tested. nVent Hoffman

Chuck Ross

In the United States, we’re well aware of a number of marking schemes that indicate how products like enclosures will perform in particular settings. These will include the National Electrical Manufacturers Association (NEMA) rating indicating how resistant a product will be in various wet, dirty or corrosive locations. There might also be a UL marking indicating a standard to which the product has been tested. But another certification mark might be less familiar, under the abbreviation “RoHS,” and it could prove important, especially for environmentally oriented projects.

The abbreviation “RoHS” stands for “Restriction of Hazardous Substances,” and it indicates compliance with a European directive that first took effect in 2006. The directive originally limited the amount of 4 metals – lead, mercury, cadmium and hexavalent chromium – along with six chemical formulations that might be used as flame retardant or for other purposes. Three years ago, four additional chemical compounds were added to the list.

In general, the restricted materials are on the list because they’ve been proven to be toxic to human health over time, even in very low quantities. Researchers have linked long-term exposure to these toxins to neurological, developmental and reproductive changes in humans.

Enclosures fall into the categories of equipment required to demonstrate compliance with the standard. Companies that manufacture enclosures for the international market often find it easier to fabricate a single, global model that meets all relevant standards, than to make multiple versions to address each market’s specific requirements.

The RoHS mark now more commonly shows up in advertising and marketing materials, such as on company websites. With the release of the updated RoHS2 directive in 2011, the broader CE label now signifies compliance to RoHS requirements, as well as to a number of other European Union environmental health and safety standards.


Photo courtesy of nVent Hoffman