UL's product certification and testing services can be mainly divided into listing, approval and classification.
1. Listing (LISTED):
Generally speaking, listing is only applicable to complete products and various devices and equipment that can be replaced or installed on site by qualified personnel. The various products that belong to UL's listing service include: household appliances, medical equipment, computers, commercial equipment, and various electrical products used in buildings, such as power distribution systems, fuses, wires, switches and other electrical components. Products listed by UL can usually be marked with UL's listing mark on each product. Usage of the listing mark.
2. Recognized (Recognized):
Recognition service is a project in UL's service. The products identified by it can only be used as components and raw materials on UL listed, graded or other recognized products. Recognized products are not complete in structure, or have certain restrictions on use to ensure the expected safety performance. In most cases, the follow-up service of recognized products belongs to Class R. Approved products belonging to the L category include electronic wire (AVLV2), processed wire (ZKLU2), wire harness (ZPFW2), aluminum wire (DVVR2), and metal flexible tube (DXUZ2). Approved products are required to carry the approval mark.
3. Classification:
The classification service only evaluates specific hazards of products, or evaluates products that implement other standards other than UL standards (including internationally recognized standards such as IEC and ISO standards). Generally speaking, most classified products are not products used by consumers, but products used in industry or commerce. The classification mark in the UL mark indicates that the product has certain restrictions and specified ranges when it is certified by UL. For example, for chemicals such as solvents used in industry, only the range of fire that may occur when it reaches the ignition temperature is evaluated. The grading service and listing service for some products are the same, but generally only one or several aspects of the product are evaluated. For example, in the United States, equipment such as medical X-ray diagnostic equipment must comply with US laws and regulations on radiation emissions and beam accuracy. However, because UL only classifies X-rays, it only evaluates its mechanical properties, electrical properties and other non-radiation properties.
