American UL certification introduction
　UL is an independent, non-profit, professional private organization that conducts tests for public safety. UL is short for Underwriter Laboratories Inc. UL Safety Testing Institute is the most authoritative in the United States, and is also the largest civilian organization engaged in safety testing and identification. It uses scientific testing methods to study and determine whether various materials, devices, products, equipment, buildings, etc. are harmful to life and property and the degree of harm; Determine, compile and distribute appropriate standards and information that can help to reduce and prevent loss of life and property, and conduct fact-finding operations. In short, it is mainly engaged in product safety certification and operating safety certification business, its ultimate goal is to get a fairly safe level of goods for the market, for the personal health and property safety to be guaranteed to contribute. In terms of product safety certification as an effective means to eliminate technical barriers to international trade, UL also plays a positive role in promoting the development of international trade.
　UL was founded in 1894, the initial stage of UL main in the fire insurance department to provide funds to maintain operations, until 1916, UL was fully independent. Over time, the organization has been recognized by the country and the world. UL certification is a voluntary certification, exported to the United States can not do UL certification, but your products do not mark the UL mark, people will not buy your products. After nearly 100 years of development, UL has become a world-renowned certification body, with its own set of strict organizational management system, standard development and product certification procedures. UL is governed by a board of directors consisting of safety experts, government officials, consumer, education, utilities, insurance, and standards representatives, with the President and Vice President handling the day-to-day work. UL currently has five laboratories in the United States, headquartered in Northbrook, north of Chicago, as well as laboratories in Taiwan and Hong Kong. The cost of UL certification is higher, because the cost of the product at the time of testing has included the insurance premium. If there is an accident in the United States, the loss will be paid by the insurance company.

　　Explanation of UL certification terms

　　"AL" LISTING，CLASSIFICATION OR RECOGNITION
　　A listing or recognition service that is requested and authorized by the applicant to be established in the name of a party other than the applicant (listed person)

　　AGENT
　　An individual or enterprise entrusted by the applicant to engage in activities with UL on behalf of the applicant

　　APPEALS PROCEDURE
　　If the customer has a disagreement with the results of the engineering test or follow-up inspection, it can be discussed with the relevant engineer or field representative without fear of jeopardizing the later conclusion. If a satisfactory answer is not received at this level, the customer can appeal to a higher level, up to the President. APPENDIX

Part of the detailed regulations, which include the responsibilities of plant and field representatives and the requirements for relevant testing. Tests performed on samples sent to UL may also be described.

　　APPLICANT   
　　Businesses or individuals who request testing of their components, products, or systems from UL. Legally, this party will be responsible for the costs of the testing and tracking services and will have rights to all information related to the results of the testing. See also Agent.

　　AUTHORIZATION PAGE
　　File on the first page of the Tracking Service Factory inspection Instructions to authorize the corresponding tracking inspection service (Class L or Class R) and the permitted certification mark

　　CATEGORY CONTROL NUMBER (CCN)
　　UL Specifies the character representation of different product categories in the UL listing, recognition, and classification service. For example, AVLV2 indicates electronic wire; QOWZ stands for portable light fixture. In general, XXXX is a listed product, XXXX2 is an approved product, XXXX7 indicates a listed product that meets Canadian standards, and XXXX8 indicates an approved product that meets Canadian standards.

　　COMPONENT
　　A part of a product, in addition to participating in the testing of the entire product as part of the complete product, needs to be tested separately for its performance and/or structure. Parts can be listed, approved, or non-listed parts.

　　CONDITION OF ACCEPTABILITY
　　These items are listed in the report of approved or non-listed parts, but are not used as a basis for inspection by the field representative. These items, based on the results of the tests, indicate the limitations and conditions for the use of the part and the complete product. For example, in the report of a certain switch, it may be indicated in the "Applicable Conditions" that the product is only suitable for currents up to 1A or temperatures up to 125C.

　　CONTROL NUMBER  
　　One of the four possible components of the UL certification mark, as specified by UL. Depending on the product category and the type of tracking service, the control number may change periodically.

　　FACTORY IDENTIFICATION
　　An identification mark adopted by manufacturers who produce the same product in different factories is used to distinguish the factory in which a product is produced.

　　FACTORY INSPECTION
　　A review conducted by a UL field representative for monitoring purposes under the UL Tracking Service Program at a manufacturer's facility where the listed (or other) products are actually manufactured.