UL Recognized Components are components that have been recognized by UL but may not be used separately; rather, they may only be used in the design of UL-certified end products.
What is the difference between UL Recognized Components and UL Listing?
When people refer to UL certification (or, incorrectly, “UL approval”), they are usually referring to UL listing. It generally applies to end products that have been tested by UL or manufactured by a certified manufacturer in accordance with the requirements of the applicable UL standards. The end customer or user can therefore be confident that the products comply with UL standards and, consequently, with the relevant occupational safety regulations, such as the National Electrical Code. The same applies to components intended for on-site assembly; these can also receive a UL listing.
UL Recognized Components, on the other hand, are components that have also been evaluated by UL but are intended exclusively for assembly by the manufacturer. In other words, they are not intended for direct use by the end customer, but rather for manufacturers who use them to build a final product. UL itself illustrates this clearly using the example of a vehicle engine. The engine alone cannot be used by the driver; only when the manufacturer installs it in a car does it become a finished product. A somewhat more practical example is power supplies, which, on their own, also serve no purpose for the end customer.
What are the benefits of UL Recognized Components?
UL Recognized Components have already been evaluated by UL and can therefore be incorporated more easily into end products. In short, using UL Recognized Components simplifies the approval process for the finished product as part of UL listing, since it is immediately apparent that the component in question meets certain minimum requirements. The reduced effort naturally translates into lower costs for the entire process. Ultimately, the use of UL Recognized Components helps reduce costs for the client.
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Who is allowed to install UL-recognized components?
The installation of parts that are UL Recognized but do not bear a UL Listing label is permitted only for manufacturers of products that have the final product as a whole evaluated by UL or who are themselves UL-certified. Installation of UL-recognized components at the product’s point of use by the user or an authorized representative is strictly prohibited and will result in the loss of UL certification for the entire product.
Why are the regulations so strict in this area? Since UL Recognized Components are intended for installation in a final product—which is evaluated as a whole by UL anyway and must be, or may only be, produced by a certified manufacturer—the requirements for these components, for example regarding short-circuit resistance or the permissible operating ambient temperature, are in some cases less stringent. More importantly, however, the safety of the end product is only ensured in conjunction with other factors, such as the correct installation of the component or adequate explosion protection. Therefore, when assessing the safety of a UL Recognized Component, the finished product must always be considered as a whole .
Conditions of Acceptability (COA)
The conditions under which UL Recognized Components can be used safely are referred to as Conditions of Acceptability (COA). They pertain both to the safe interaction of the components with one another (e.g., the use of compatible parts) and to the safety of the component in the finished end product. An example of the latter is live, non-insulated components; these may be UL Recognized Components and may be used if safety is ensured by the fact that the control cabinet as a whole is designed to protect the user from coming into contact with live parts—for example, by being equipped with an interlock.
The Control Cabinet: A Practical Example of the Use of UL Recognized Components
UL-recognized components are not used to the same extent in all product categories certified by UL. Control cabinets, in particular, are often constructed using such components. The requirements for the safe construction and protective devices of a control cabinet are specified in the UL 508A . Only when these requirements are met can the control cabinet be certified in accordance with this UL standard. While the use of UL Recognized Components significantly simplifies the assembly process, it is not, strictly speaking, a prerequisite for successful UL listing of the end product.
What does the use of UL Recognized Components mean for the end customer or exporter?
An exporter who, for example, wishes to ship a piece of equipment or a machine to the U.S. or Canada and, for this purpose, orders a UL-certified control cabinet from a control cabinet manufacturer, must primarily ensure that the control cabinet as a whole bears a UL Listing Label. This means that the product has what is commonly referred to as UL certification. If, however, such a label is missing and only the individual components are marked as “UL Recognized,” UL itself recommends treating the control cabinet as an unlisted product.
Zusammenfassung
Components and parts that have been evaluated by UL and are intended for further processing by the manufacturer are referred to as UL Recognized Components. The use of Recognized Components simplifies the manufacturing process, as it is immediately apparent that they meet UL’s requirements. However, components bearing the UL Recognized Components label may only be used by manufacturers who are themselves UL-certified or who have the control cabinet UL-certified after completion.
