UL is Underwriter Laboratories Inc. in short. UL Safety Testing Institute is the most authoritative private safety testing in the United States and the largest private institution engaged in safety testing and identification in the world. It is an independent and non-profit, professional organization that tests public safety. It adopts 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; it also determines, compiles and publishes relevant standards and documents that help to reduce and prevent losses of life and property, and carry out fact-finding services.
UL is Underwriter Laboratories Inc. in short. UL Safety Testing Institute is the most authoritative private safety testing in the United States and the largest private institution engaged in safety testing and identification in the world.. It is an independent and non-profit, professional organization that tests public safety.It adopts 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; it also determines, compiles and publishes relevant standards and documents that help to reduce and prevent losses of life and property, and carry out fact-finding services. In summary, it is mainly engaged in product safety certification and operation safety certification business, and its ultimate purpose is to provide the market with a fairly safe level of commodities, and to contribute to the protection of personal health and property safety. In terms of product safety certification as an effective means to eliminate technical barriers to international trade, UL also plays an active role in promoting the development of international trade.
UL was founded in 1894. At the initial stage, UL mainly relied on the fire insurance department to provide funds to maintain its actions. Until 1916, UL was completely independent. After nearly 100 years of development, UL has become a world-renowned certification body with a complete set of strict organizational management system, as well as standard development and product certification procedures. UL is managed by a council composed of representatives from safety experts, government officials, consumers, educators, public utilities, insurance industry and standards departments, and is managed by its President and Vice President. UL currently has five laboratories in the United States, headquartered in the town of Northbrook in northern Chicago, and has established corresponding laboratories in Taiwan and Hong Kong.
Significance of the UL Certification
The significance of the UL certification mark for enterprises:
1. The entire American market attaches great importance to product safety; consumers and buyers tend to choose products with the UL certification mark.
2. UL has a history of more than 100 years. The image of safety is deeply rooted in consumers and governments. Even if you do not directly sell to consumers, the middlemen will also ask for products with the UL certification mark for products to sell well.
3. American consumers and purchasers have more confidence in the company's products.
4. The federal, state, county, and city governments across the United States have more than 40,000 political districts, all of which recognize the UL certification mark.
The applicant submits relevant company and product information.
Written application: you may request UL to test your company’s products in writing.
Company information: detailed and accurate name, address, contact person, postal code, telephone and fax of the following shall be provided both in Chinese and English.
(a) Applicant: the company that has submitted a product testing application and is responsible for all engineering service charges
(b) Listed companies: companies whose names are listed in various product catalogs published by UL
(c) Production factories: manufacturers and producers of products.
Product information: product information shall be provided in English.
(a) Product name: Provide the full name of the product.
(b) Product model: List all product models, varieties or classification numbers that need to be tested.
(c) Intended product applications: for example, homes, offices, factories, coal mines, ships, etc.
(d) Parts inventory: details of the parts which comprise the product and models (class numbers), ratings and names of manufacturers. For insulating materials, please provide names of raw materials, such as GE Polycarbonate, Lexan Type 104. When a part is UL certified or approved, please note the specific model of the part and indicate its UL file number
(e) Electrical properties: for electrical and electronic products, please provide the electrical schematic diagram (circuit diagram) and electrical performance table.
(f) Structural drawings: for most products, a structural drawing or exploded view of the product and a material inventory etc. are required.
(g) Product photographs, instructions for use, safety, etc., or product installation instructions.
Decisions are made based on the product information provided.
When product information is complete, UL engineers will make the following decisions based on the submission: the UL standards for the experiments, the test engineering cost, the test duration, the sample size, etc. UL will notify you in writing and send the official application form and follow-up service agreement to you. The charge limit indicated in the application form is the maximum engineering cost UL estimates based on the test items. Without your written authorization, the cost limit shall not be exceeded. The applicant shall make remittance and send back the application form and samples.
The UL Certification
The applicant signs the application form and follow-up service agreement and sends the form back to UL. At the same time, the applicant shall make bank remittance and send out sample at the post office or by express mail. Please make adequate explanations on the test samples (such as name and model). Please send the application form and samples separately. For each application item, UL will designate a unique Project No. The applicant shall indicate clearly the Project No. and the name of the applicant when making the remittance and sending samples and application forms for UL to check.
Upon receipt of your signed application form, remittance and test samples, UL will notify you of the completion date of the test plan. Product testing is generally performed at UL laboratories in the United States, and UL may also accept audited participating third-party test data. Test samples will be returned or destroyed as per applicant’s request.
If the product test results meet the requirements of the UL standard, UL will issue a test conformance report and a Follow-up Service Procedure. The test report will detail the test conditions, sample performance indicators, product structure and safety mark appropriate for the product. The Follow-up Service Procedure includes a product description and instructions to the UL regional inspector. A copy of the test report is sent to the applicant and a copy of the Follow-up Service Procedure is sent to each manufacturing factory.
The applicant receives the authorized use of the UL mark
The UL regional inspector shall contact the production factory in China for the Initial Production Inspection (IPI). The inspector shall check your product and its parts in the production line and warehouse inventory, so as to confirm whether the product structure and parts are consistent with the Follow-up Service Procedure. The regional inspector will also carry out a witness test if the Procedure states so. When the test results meet the requirements, the applicant will be authorized to use the UL mark.
After IPI, the inspectors will check the factory from time to time. Inspectors will check the product’s structure and conduct screen tests. The checking frequency is determined by the types of products and output, and most types of products are checked at least four times a year. The inspector conducts such inspections to ensure that products continue to be consistent with the UL requirements. Before you plan to change the product structure or parts, please notify the UL. For minor changes, it is not necessary to repeat any experiment, and UL can quickly modify the Follow-up Service Procedure so that the inspector can accept this change. When UL believes that a product change affects its safety performance, it is necessary to apply for the applicant to resubmit the sample for necessary testing.
The cost of the follow-up services is not included in the test charges.
If the product test results do not meet the UL standard requirements, UL will notify the applicant to explain the problems. After the applicant improves the product design, the product can be re-inspected. You should tell the UL engineer what improvements the product has made for their decision making 
1. UL inspection rules, certification review and follow-up inspection
2. The inspection of the UL inspector is basically a mechanical operation. Depending on the different product, the inspection is based on Bulletin, Procedure, Follow-up Inspection Instructions (FUII) (if any, it is included in the by-law) and UL standards (if required in FUII). If the inspector visits the factory and the factory is producing UL products or stocked UL products, the inspector will take samples in one of the following ways:
1. Extract each part from the production line plus a complete product extracted from the warehouse.
2. Extract each part from the warehouse plus the complete product on the production line.
3. Extract the complete product from the warehouse for disassemble.
The exact number of samples is determined by the rules, FUII, SAP (Standard Attachment) or direct orders from the UL Laboratory. Inspectors do not necessarily inspect all products at each inspection, but they will try to inspect all product categories or models within one year or at least two years.
Generally speaking, UL does not set up high requirements for the production system in a factory. Equipment are only required to be measured annually. The factory is required to preserve their own inspection records and have certain control methods for unqualified products.
At the time of inspection, the on-site representative (UL inspector) will focus on the product itself, and they will check the structure, components and assembly of the product one by one according to the above inspection basis. For parts related to product safety, the general rules specify the requirements for UL-certified products, and will indicate the manufacturer and model; for housing, shields and other injection molded parts, the general rules will specify the raw materials and size requirements. The on-site representative will check the UL mark as specified in the above items and rules.
In addition, if the specification, FUII or the standards requires on-site product testing, the site representative will ask the factory inspector to conduct the corresponding tests, while the on-site representative will witness. If the rules also require the samples to be sent to UL for follow-up tests, the factory shall cooperate with the inspector to produce the corresponding sample. After the inspector writes the sample label, provides the address and seals the sample, the factory shall send it to the corresponding UL laboratory.
If the products produced by the factory fully comply with the requirements of the corresponding UL inspection standards and there is no other violation of the Follow-up Service Procedure, the inspector will issue an Inspection Report; the factory representative should sign on the report after confirming the correctness of its content; and one test is completed. If there is a non-compliance with the inspection standard during the inspection, the inspector will issue a Variation Notice and take appropriate measures based on specific circumstances.
Removal of the UL mark
In case of unauthorized use of the UL mark, the inspector will demand removal of the UL mark; for products that do not meet the UL requirements, the inspector will ask the factory to remove the UL mark or rework for the product to meet such requirements; if the factory disagrees with the above treatment, the UL mark is temporarily kept but the shipment must stop. The inspector will inform the corresponding laboratory of the case and UL will reply to decide whether the UL mark may be retained. If minor problems occur and the product safety is not affected, the inspector will make a provisional acceptance decision and report it to the appropriate laboratory; however, if obvious standard errors occur, such as typos or unit errors, which will not affect the conformity of the product, the inspector will still issue a notice of change as part of the UL documents. Under normal circumstances, unless it is the responsibility of UL, the inspector will ask the factory to explain the non-conformity to the corresponding laboratory, and UL will respond accordingly to the explanation.
Certainly, the inspector's judgment is provisional, and the final decision is on the respective UL laboratory. If the factory disagrees with the inspection method, it can be fully reflected to the corresponding laboratory. At this time, the inspector is obliged to provide the corresponding contact person and contact method. The factory representative shall sign the notice after confirming that the contents recorded in the change notice are correct.
UL certified production inspection
The UL regional inspector shall contact the production factory in China for the Initial Production Inspection (IPI in short). The inspector shall check your product and its parts in the production line and warehouse inventory, so as to confirm whether the product structure and parts are consistent with the Follow-up Service Procedure. The regional inspector will also carry out a witness test if the Procedure states so. When the test results meet the requirements, the applicant will be authorized to use the UL mark.
After IPI, the inspectors will spot check the factory from time to time. He or she will check the product structure and conduct witness tests. The checking frequency is determined by the types of products and output, and most types of products are checked at least four times a year (The cost of the follow-up services is not included in the test charges).
Before the first batch of UL certified products are shipped, they must be authorized by UL's local provincial and provincial China Import and Export Commodity Inspection Bureau (CCIC) to send people to the factory for review. Follow-up inspection is also required every year.
Introduction to the follow-up inspections
As an integral part of UL certification, UL has established a follow-up inspection system to ensure that UL's listing and approved products continue to meet the UL standards and requirements. Follow-up inspection refers to the follow-up inspection of UL products by UL's on-site representatives all over the world at local factories. The purpose is to ensure the manufacturer’s production process, inspection process and products continue to be in compliance with the UL requirements, by inspecting the manufacturer's production process, inspection process and products referencing to the UL requirements and Follow-up Service Procedure.
Basis for follow-up inspections
After the on-site representative arrives at the factory, the inspection is mainly carried out according to the Follow-up Service Procedure. The Follow-up Service Procedure was prepared by the UL Engineering Department after testing the samples submitted for inspection. This document includes a comprehensive description of the product, including photographs, instructions, and so on. It also stipulates the various tests often performed by manufacturing factories during production, some of which require a 100% coverage of products, such as the high-voltage holding test. Some inspections can be carried out by sampling, and test items that must be spot-checked by the on-site representative at the factory site inspection are also specified. The on-site representative make judgments about whether the test results are in compliance based on the detailed information and regulations of such tests.
Product categories for follow-up inspections
The review is divided into the first review and quarterly reviews. The cost of the first review is relatively higher. The UL follow-up test is divided into R and L categories. Type L services are mainly used for products related to life safety, such as fire extinguishers, smoke detectors, fire doors, and some products with considerable output, such as electrical equipment, wires, and circuit breakers. For products belonging to category L, the manufacturer must directly order labels from UL to attach to the products. Type R services are mainly used for electrical equipment, such as electric fans, televisions, hair dryers, ovens and other products that are usually produced by corresponding assembly lines.
1. The minimum height of the registered trademark should be 3/64 inches.
2. When the outer diameter of the UL mark is less than 3/8 inch, the registered trademark symbol can be ignored if it is not clearly readable with naked eyes.
3. The mark can be directly and fixed on a stable product by stamping, molding, ink printing, screen printing or similar methods.
4. Obtaining the mark: the manufacturer can reprint or obtain it from a UL authorized dealer.