UL standards, involving almost all types of products, it is the basis for identification of products. UL 500 standard was published, of which 70% of American National Standards Institute (ANSI) adopted as American National Standards.

1) UL standard structures

In general, UL standard in the structure can be divided into:
(1) standard range of products involved;
(2) The structure of the product requirements;
(3) The raw materials used in the product requirements;
(4) components used in the product requirements;
(5) UL laboratory samples test equipment requirements and test methods;
(6) of the factory test equipment manufacturer requirements and test methods;
(7) product signs and instructions required.

2) UL standard revision

UL standard is a continuous improvement document. UL standard revision required by the industrial sector, users, UL engineers or other interested parties proposed.

Industry modify the program: When the need to modify some elements of UL standards, the requirements of the product will have a corresponding change, for, UL has developed formal procedures for industry changes.

Each of the UL standards in his part to change the effective date will be announced. At the effective date of inspection services are UL track the product must be in accordance with the requirements of the new changes accordingly, so the date change from the standard of play between the effective date of announcement left plenty of time to change their own factory UL tests products and submit again.

Formal request through the change to the implementation of revised procedures for the industrial sector. The program includes: sending formal notice to the applicant to change the start date, identified by the UL engineer the product in accordance with the same methods to help the applicant check the product need to change elements, and modify the UL in the factory prior to the effective tracking of inspection documents.

After the commencement of the new standard, UL inspection representative will visit manufacturers, according to a request for amendment to change the corresponding part of the review.