1. Introduction to UL Certification

UL certification was established by Underwriters Laboratories, Inc., and is one of the most authoritative safety certification systems worldwide. As a non-profit private safety testing and certification organization, UL is committed to evaluating the safety performance of products during use through scientific testing methods and strict standards. Its core coverage includes electrical, electronic, mechanical, building materials and other fields, especially setting an industry benchmark in preventing safety risks such as fire and electric shock.

UL certification is not only a core access credential for the North American market (the United States and Canada) but also widely recognized globally. Currently, UL has formed a standard system covering more than 1,000 product categories, and its certification results are listed as a necessary condition for shelving by major e-commerce platforms such as Amazon and Walmart and offline retail channels, becoming an important endorsement of product safety performance.

2. Introduction to UL Certification Marks

UL marks are divided into three categories according to service types, which cannot be mixed; otherwise, they will be regarded as counterfeit products. The specific categories and application scenarios are as follows:

Listed Mark: Applicable to complete products and field-replaceable devices, such as IT equipment, AV equipment, refrigerators, vacuum cleaners, etc. Products must pass full UL testing to prove no fire and electrical hazard risks before using this mark, which is the most common UL mark type for end consumer goods.
Recognized Mark: Targeted at components and materials, such as switches, power supplies, printed circuit boards, transformers, flame-retardant plastics, etc. Such products must meet specific approval conditions and ensure compatibility with finished product standards when used for assembling finished products. It is an important safety certification mark for upstream components in the industrial chain.
Classified Mark: Used for products with special performance in commercial/industrial environments, such as building materials, fire protection equipment, marine equipment, etc. Certification evaluation is based on relevant laws and regulations, focusing on the risk and applicability of products in specific scenarios.

In addition, the UL mark also includes the cUL version for the Canadian market. Synchronized testing can meet the standard requirements of both the United States and Canada simultaneously, simplifying the cross-border market access process.

3. Significance of UL Certification for Enterprises

The value of UL certification for enterprises runs through multiple dimensions such as market access, brand building, and risk control, specifically reflected in:

Breaking Market Barriers: As a mandatory safety certification in the North American market, the UL mark is a "pass" for products to enter mainstream channels such as Amazon and Walmart. Products without certification will face the risk of being removed from shelves or banned. At the same time, the recognition of UL certification in regions such as Singapore and Australia is constantly improving. For example, the UL 9540A energy storage standard has been incorporated into local mandatory requirements, helping enterprises expand the global market.
Enhancing Brand Trust: UL's century-old accumulated safety credibility can effectively enhance consumer confidence. Research shows that products with UL marks have an average premium capacity increase of 10%-15% in the terminal market, and the user repurchase rate is significantly higher than that of non-certified products.
Reducing Operational Risks: Through UL's strict testing and factory inspections, enterprises can detect product design defects in advance (such as insufficient insulation and substandard flame retardant grade), avoiding recall, litigation, and brand reputation losses caused by safety accidents.
Optimizing Supply Chain Management: The UL Recognized Mark can help enterprises screen compliant component suppliers, ensure uniform safety standards upstream and downstream of the industrial chain, and reduce the risk of batch product non-conformity caused by component problems.

4. UL Certification Process

The UL certification process covers the entire cycle of application, testing, factory inspection, certification acquisition, and maintenance. The standard cycle is approximately 24 weeks (including testing + factory inspection). The specific steps are as follows:

Preliminary Preparation and Application: Enterprises clarify the product category and applicable UL standards (such as UL 62368-1 for audio-visual equipment, UL 1012 for power adapters), submit the application form and technical materials (circuit diagrams, BOM lists, user manuals, etc.). After evaluation by UL engineers, the testing standards, costs, sample quantity, and cycle are determined.
Product Testing: Samples are sent to UL laboratories or their authorized third-party laboratories (required to have ISO 17025/ILAC qualifications) for testing. Core items include: electrical safety testing (withstand voltage, leakage current), mechanical safety testing (structural strength, electric shock prevention), environmental testing (high and low temperature, humidity), and abnormal condition testing (short circuit, overload simulation). If the test fails, the enterprise needs to adjust the design or replace materials according to the rectification report and retest.
Factory Inspection: After passing the test, UL conducts the Initial Production Inspection (IPI) to evaluate the production line, quality control system, and raw material traceability capabilities. After obtaining the certification, annual Follow-Up Service (FUS) inspections are required. Most products are inspected at least once a quarter to ensure the consistency between mass-produced products and test samples.
Certification Issuance and Mark Usage: After passing the factory inspection, UL issues the certification certificate and authorizes the enterprise to use the corresponding UL mark. Enterprises must strictly follow the mark usage guidelines and shall not modify the style or scope without authorization.
Post-Certification Maintenance: The validity period of the certificate depends on the product type and needs to be updated regularly; enterprises must notify UL in advance before changing the product structure or components, and major changes require re-testing.

5. Relevant Standards and Directives (Key Updates in 2025)

UL standards are continuously iterated to adapt to technological development. The following key standard updates in 2025 have a significant impact on enterprises:

Information Technology and Audio-Visual Equipment (UL 62368-1:2025): Globally mandatory implementation from July 31. Core changes include: components must comply with the new standard (no longer accepting IEC 60950-1/IEC 60065 old standard components), lithium battery safety extended to non-portable equipment, and new testing requirements for liquid cooling systems ≥1 liter (for data center equipment).
Battery and Energy Storage Systems (UL 9540A:2025): Refines the definition of thermal runaway "propagation" (no external energy transfer is required, only exhaust does not count as propagation), adds testing for lead-acid/nickel-cadmium/high-temperature/flow batteries, uses "test wall" instead of NFPA 286 test room for residential energy storage, and has been incorporated into mandatory standards in Singapore and Australia.
Cleaning Equipment (UL 1776): Amazon compliance requires test reports to be issued by ISO 17025/ILAC laboratories. Test contents include electrical safety, hose burst strength, IPX4+ waterproof rating, and battery overcharge protection (when applicable), covering high-pressure cleaners and battery-powered cleaning equipment.
Robots (UL 3300): The first safety standard for commercial/consumer robots, evaluating multi-directional motion safety, human-machine interaction collision prevention, and fire/electric shock prevention design, applicable to service, education, and entertainment robots.
Printed Circuit Boards (UL 796/796F): Adds requirements for copper cladding and Via spacing, and strengthens material fire testing (such as the minimum PI film thickness and adhesive thickness matching).

6. Notes

UL certification compliance directly affects enterprise market access and operational safety. The following matters should be focused on:

Response to Standard Updates: Timely track the standard expiration time. For example, UL 1598C lighting certificates will expire after September 8, 2025. Enterprises need to plan product upgrades and re-certification in advance to avoid sales impact due to certificate suspension.
Avoid Common Failure Points: Structurally ensure that insulation materials reach UL 94 V0 flame retardant grade and PCB electrical clearance meets requirements; component selection must be compatible with the new standard (such as UL 62368-1:2025 prohibits old standard components).
Mark Usage Specifications: Strictly mark the mark according to UL guidelines, and shall not reduce, deform or confuse it with other marks; Listed, Recognized, and Classified marks cannot be mixed, and illegal use will face legal liability.
Factory Inspection Preparation: Daily retention of raw material purchase records, test reports, and production process documents to ensure that UL inspectors can trace product compliance; conduct internal self-inspections at least once a quarter to rectify potential problems in advance.
Cost and Time Efficiency Optimization: Adopt the strategy of "pre-test + series model certification", use third-party laboratories to identify problems in advance, and sharing test reports for the same series of products can reduce repeated costs by more than 30%; the cycle can be shortened to 1 week for scenarios requiring only test reports (such as UL 1776).