The NRBX is a Category Code Number (CCN). As such, it stands for UL 698 A. This UL standard specifies the requirements for control cabinets that are directly connected to a potentially explosive atmosphere.
NRBX and UL 698 A
UL 698 A specifies the requirements for control cabinets that are not installed directly in a potentially explosive atmosphere (Ex zone) but are connected to it—for example, because they control a system located in an Ex zone. Colloquially, this is referred to as an Ex-i area. U.S. occupational safety regulations require that special precautions be taken with such control cabinets to increase their intrinsic safety. To this end, technical barriers must be installed at the connections to the Ex zones to prevent a malfunction in the control cabinet from affecting the potentially explosive area.
Components must comply with NRBX
For a control cabinet to meet the requirements of UL 698 A, only components bearing an approved Category Code Number from UL 698 A or NRBX may be used in its construction. In other words: The UL standard lists the CCNs of the product categories that may be used in construction; approved components, in turn, can be identified by their corresponding CCN. Of course, simply using the appropriate components is not sufficient on its own to comply with UL 698 A. In addition, the design requirements specified in the standard must be followed to ensure that a control cabinet complies with the standard.
Also note the following for replacement parts: NRBX
What happens if a replacement part is needed for a UL-certified control cabinet? In principle, it is possible to install components in a UL-certified control cabinet that are not identical to the original components. However, this requires recertification of the entire control cabinet. Therefore, the simplest approach when replacing components in a control cabinet is to use only replacement parts from the same product category. Anyone who needs a component for a control cabinet certified to UL 698 A should ensure that the replacement parts, at a minimum, belong to the approved NRBX product categories.
NRBX and Manufacturers
But how do you find out which manufacturers offer products in the relevant category? Fortunately, it’s quite simple: UL lists them in its database called UL Product iQ lists all manufacturers that meet a specific UL standard and whose products are therefore assigned the corresponding Category Code Number (CCN). You can also search for the relevant CCNs there. Furthermore, the database provides information on the various product categories manufactured by each company. For example, under the keyword NRBX in the control panel construction section, you’ll naturally find Krayer as well.
What does NRBX stand for?
Like all Category Code Numbers, NRBX is not an acronym but a code. The letters therefore have no specific meaning. The CCN makes it possible to determine the product category of a product certified according to UL standards. A component bearing an approved NRBX Category Code Number may therefore be used in a control cabinet that controls technical equipment located in a potentially explosive atmosphere; however, the control cabinet itself must not be installed in that area.
What is the significance of the NRBX for Canada?
Due to the mutual recognition of U.S. and Canadian standards, an NRBX certification is also valid in Canada, where CSA standards apply. Therefore, there is no need to apply for a separate certification for the Canadian market—and, of course, the same applies in reverse. The only difference lies in the nomenclature: In Canada, a digit or suffix is added to each CCN. The Category Code Number for UL 698 A is NRBX-7 there.
Zusammenfassung
NRBX is the Category Code Number for the UL 698A standard, which defines the requirements for control cabinets in the Ex-i zone. All components installed in a control cabinet in an Ex-i zone must belong to product category NRBX or another CCN approved by UL 698A. Using the Category Code Number NRBX, you can easily search the UL database to find the components and parts that are permitted for use in a control cabinet that must comply with the requirements of UL 698A.
