The Ultimate UL Guide

What Does UL Mean? UL Standard Accreditation
What Do Approved, Listed and Recognized Mean? What Are the Differences Between UL Listed and UL Recognized?
How Do I Know Whether a Product Needs Recognized or Listed? Difference Between UL and ETL
What Do Other UL Logo Markings Mean? Why Use UL Rated Products?

Ensuring each application meets requirements is one of the most important things for industrial businesses. Not only do the applications need to work appropriately and safely, but the individual pieces incorporated into the application need to meet several requirements to ensure the safety of employees, customers and the public.

One of the primary things most will look for when inspecting a control panel or machine is an indication that each individual part of an installation meets certain standards.

UL is probably the most commonly sought safety certification mark when it comes to electrical equipment, with the UL Listing Mark recognized as the most common certification mark seen and accepted by code authorities worldwide.

Businesses concerned about meeting requirements for their industrial applications need to understand the full meaning of each of these marks, as well as the differences among them and which marks will work for certain industrial applications. This guide will clarify each of these points for you.

UL Common mark

What Does UL Mean?

The acronym “UL” stands for Underwriters Laboratories. The word “underwriters,” in this context, indicates a group of individuals who assess the risk of a product and validates the acceptability of the risks associated with the product according to their internal set of standards.

This American company is a product safety testing and consulting organization that standardizes safety certifications for numerous products. The UL Mark, therefore, indicates the UL group’s approval of the marked product under associated safety testing protocols.


Underwriters Laboratories was originally established in 1894 as the Underwriters’ Electrical Bureau, a branch of the National Board of Fire Underwriters. The company, founded by William Henry Merrill, started out as an electrical safety consulting firm, testing and designing equipment while uncovering the hazards associated with the growing world of electronics.

The organization grew throughout the 20th century, changing its name to its current iteration and developing safety tests and standards that would become popular throughout the electronics industry. Today, Underwriters Laboratories is a not-for-profit organization headquartered in Illinois with offices maintained across 46 countries.

With more than a century of history in the field, Underwriters Laboratories is possibly the most recognized and respected third-party safety certification organization in the industry.

The primary goal of UL is to ensure each product they evaluate is safe to put in the public marketplace. Among their many services, UL provides safety testing, inspection, certification, validation, auditing, advising and training services for a wide range of clients. Manufacturers, retailers and policymakers alike turn to UL for their expertise in the field.

UL indicates their approval of a product by allowing vetted organizations to use a specific UL mark in their marketing and packaging. During each given year, UL evaluates billions of products to determine if they deserve a UL mark, and over 10 billion qualify and enter the marketplace with a UL mark on their packaging or casing.

However, not all these marks are created equal. UL has several different standards for different product categories, and it rates products within these categories at different tiers. UL can certify the quality of product in the field when requested.

UL Standard Accreditation

UL is accredited across several countries as a standards certification organization and is recognized both in the electronics industry and at a federal level. A few of the organizations that recognize UL include:

  • OSHA. UL is a Nationally Recognized Testing Laboratory, which means that UL is one of the few companies approved to perform safety testing by the US Occupational Safety and Health Administration.
  • ANSI. UL is accredited in the US by the American National Standards Institute as an audited standards designator.
  • SCC. UL marks are accepted in Canada as of 2013 since they are accredited by the Standards Council of Canada. This means UL is a nationally recognized Standards Development Organization, or NDO, that helps to develop Canada’s set of national standards.

Organizations That Recognize UL

What Do Approved, Listed and Recognized Mean?

When considering products boasting UL marks for an industrial application , there are a few different UL ratings that are more commonly seen than others. These include UL Approved, UL Listed and UL Recognized. These are explained in more detail below:

  • UL Approved. Many companies claim in their advertising and on their packaging that their product is UL Approved. While this is a common phrase for advertising, this term isn’t an appropriate reference to their UL mark. “UL Approved” isn’t a mark provided by UL – usually companies using this phrase mean that their product is either UL Recognized or UL Listed.
  • UL Listed. The UL Listed Mark is the most common certification mark found on industrial electronics and products. This is also the mark most commonly accepted by code authorities. Products Listed by UL are usually complete appliances, like computer equipment, heaters and electrical panelboards. It’s also commonly seen on emergency and safety equipment, like fire extinguishers, personal flotation devices, smoke detectors and even bullet resistant glass.

UL Listed Mark

In most cases, products seeking UL Listing tend to be intended for installation by national safety codes like the National Electrical Code® or otherwise have something to do with workplace safety. Products that carry this UL Listed Mark have been tested and investigated by UL using applicable performance requirements.

The results of this testing show the UL Listed product provides a safe and code-compliant installation when installed according to the manufacturer’s instructions. In this case, a safe installation means that the installation has been found to be reasonably free of the risk of fire, electric shock and other hazards to public health.

  • UL Recognized. The UL Recognized mark is another common mark, though it is found on slightly different products than the UL Listed mark. UL Recognition only applies to products that are components or are otherwise incomplete or limited in their performance capabilities. In other words, these products are intended to be used as part of a larger installation or product and don’t alone constitute a final product.

Often, these components require additional installation precautions to be deemed completely safe, like housings or protective casing. A common example of such a component is an appliance wiring material, which is used as a part of a larger whole, rather than an appliance in itself.

Components verified with this mark have been deemed by the UL as meeting similar safety requirements as UL Listed products when used according to the manufacturer’s instructions and intentions.

What Are the Differences Between UL Listed and UL Recognized?

Most individuals confuse UL Listed marks with UL Recognized marks, thinking they mean the same thing. Even industrial business owners fail to realize the differences between the two, lumping them both under the incorrect “UL Approved” umbrella. However, several key differences between these two ratings must be understood, especially by organizations looking to build regulation-compliantapplications.

These differences include the following:

  • Component v. Appliance. UL Listed approvals are usually applied to complete products and appliances, though they can apply to components under very rare circumstances. On the other hand, UL Recognized marks are only ever applied to components.

UL Listed Approvals

  • Relationship to Industry Standards. UL Listed requirements tend to follow stricter industry and national safety standards as compared to UL Recognized requirements. This is one of the reasons why it is more common to see UL Listed approval marks on products intended for installation in harsh environments.
  • Ease of Achievement. Between the types of applicable products and the industry standards those products need to follow, UL Listed marks are much harder to obtain than UL Recognized marks. UL recognized approvals are easier to attain both because of the looser requirements and because manufacturers can pick and choose which components of a product they want to be recognized, rather than have a product rated as a cohesive whole.

How Do I Know Whether a Product Needs Recognized or Listed?

Each product  is different, so choosing between a UL Listed and a UL Recognized product for any single application requires close consideration. Three of the primary things to consider when assessing the needs of an installation are:

  • Application. The environment in which your installation will operate plays a large role in which type of UL-rated product you want. Because of the more stringent requirements associated with the rating, UL Listed products tend to be a better choice for installations in harsher environments. Additionally, these products have been assessed as a whole, rather than in parts, and have been proven to be safe in most foreseeable applications.

UL Recognized products may still be a decent choice, provided they are used and protected appropriately for the application. However, implementing such precautions may require additional planning.

  • Completion. UL Recognized marks only ever apply to components, and these components may need additional protections to make them appropriate for your application. This may include a protective casing to keep the component shielded from damage from dust, liquids and physical impact.

UL Recognized

Sometimes, a product may contain a UL recognized component, in which case the product as a whole needs to be assessed to see if it needs to be protected or adjusted. Though similar considerations may be necessary to make a UL Listed product fit your particular application, you’ll likely need to do less to bring one of these products up to code.

  • Standards. As previously discussed, UL Listed products must meet stricter standards than UL Recognized components. For certain applications where the installation must meet strict industry standards, this distinction may play a large role. If high standards are a concern for an application , a UL Listed product may be a better choice than a UL Recognized one.

What Do Other UL Logo Markings Mean?

Though UL Listed and UL Recognized are the two most common ratings you’ll see on most products, there are several others you can find that differ based on their requirements and applicable products. These ratings include the following:

  • UL Classification. This mark means Underwriters Laboratories tested and evaluated samples of the product in question, looking at the safety of particular properties of the product. While this UL Classification does assess these properties according to the same standards for safety as those marks previously discussed, it’s important to consider the particular properties the UL assessed.

Manufacturers of UL Classified products will usually pick and choose which properties of a product they want UL classification for, so researching the scope of the UL’s study may be important to determining the appropriateness of the product for a specific application. This UL Classification mark may be seen on both components and complete appliances, usually accompanied by a disclaimer listing the properties studied.

  • UL Performance Verification. This UL rating means Underwriters Laboratories tested and evaluated samples of the product against a particular performance standard. Typically, these performance standards are national or international industry performance standards, manufacturer’s internal standards or the UL’s requirements like the UL XTR Structured Cabling Program.

This UL Performance Verification mark will usually be accompanied by a statement indicating the scope of the verification and which standards the UL evaluated the sample against. Again, this mark may be seen on both complete appliances and incomplete components accompanied by the particulars of the performance verification process.

  • UL Functional Safety Listing. The Functional Safety Listing Mark means that Underwriters Laboratories evaluated samples of the marked product to determine if the product met the UL’s safety requirements in addition to a published functional safety standard.

While the UL’s safety requirements state the product must pose no feasible risk of fire or hazard, a functional safety standard requires the product completes its intended function. Typically, this investigation involves evaluating the product’s circuits and assessing them according to process safety ratings regarding software, hardware, environmental stress factors and safety lifecycle management.

Functional safety standards usually fall into one of the following safety level classifications — Safety Integrity Level (SIL), Automotive Safety Integrity Level (ASIL), Performance Level (PL) or Class. The product is then assessed accordingly and their safety standard determined. This is indicated in conjunction with the Functional Safety Listing Mark, usually on the packaging or in the product disclaimer. Like a UL Listing, this rating is usually applied to complete appliances rather than components.

Safety Standards

  • UL’s Functional Safety Recognition. Underwriters Laboratories also provides a UL Functional Safety Component Recognition mark, which acts similarly to a UL Functional Safety Listing in that it evaluates a component for functional safety in addition to existing UL safety requirements.

The difference is similar to the difference between a UL Listing and a UL Recognition — a UL Functional Safety Recognition is awarded to components and materials to be used in an end product, rather than an end product itself. End products fall under the jurisdiction of the UL Functional Safety Listing Mark.

Simultaneously, this mark is very different from a UL Recognition in that the component in question is intended for a particular application rather than a broad one. If you see this mark on a component’s packaging, it will usually be accompanied by details of the functional safety standard with which the component was assessed.

  • Regional Marks. UL standards are used across the world, with variations on the above marks seen in each of the 46 countries in which they are applied. A few examples of region-specific UL Marks include the C-UL Mark for Canada, the UL-BR Mark for Brazil, the UL-AR Mark for Argentina, the S-Mark for Japan, the D-Mark for Denmark, the UL GS-Mark for Germany and the UL-MX NOM Mark for Mexico.

All these marks live up to the same standards as the American UL marks but are given out by different branches of the UL organization.

Difference Between UL and ETL

While UL is one of the most widely recognized safety testing laboratories in the nation, it is not the only one. Several other laboratories are available that are recognized by code authorities and standardization organizations and are similarly reputable. One of these recognized laboratories is ETL, which stands for Electrical Testing Laboratories.

UL and ETL are both Nationally Recognized Testing Laboratories (NRTL), meaning they meet federal OSHA requirements for product testing and certification. In fact, both have been around for over a century — ETL was founded by Thomas Edison in 1896, soon after William Henry Merrill founded Underwriters Laboratories.

Difference Between UL and ETL

Both laboratories meet the requirements of OSHA Nationally Recognized Testing Laboratories in that they provide independent third-party safety and quality assessments and certifications for manufactured products. They both undergo regular audits to ensure their third-party status and continuous dedication to safety assurance.

They even assess products according to similar, widely accepted product safety standards and require regular follow-up inspections with certified manufacturers to verify the continued compliance of assessed products and practices.

Essentially, the only major differences between these two organizations are their marks. Some of the particulars, like product re-certification requirements, differ between the two certification types, but these are concerns for product manufacturers rather than users.

Code authorities recognize both entities as equally valid, and both are accepted in the United States, Canada and other countries across the world. They even provide similar ratings for products, and many companies will seek an assessment from both entities for the sake of customer assurance.

Why Use UL Rated Products?

Product certification is an essential part of building a compliant electrical application . However, some industrial businesses still question why they should seek out products with UL Marks and similar certifications. UL ratings are important because:

  • Third Party Certification. UL marks and other related certifications are provided by third party certifiers, meaning the marked product has undergone unbiased safety assurance assessments. This will often include periodic, unannounced on-site inspections at the product manufacturer’s factory to ensure their processes protect the safety of their customers.

Without this third-party safety assurance, there’s no guarantee the product purchased lives up to industry standards.

  • Differentiated Ratings. Because no two UL ratings mean the same thing, businesses know what to expect from each rating, and what rating they should seek for each application. This means much more than a broad-sweeping certification that might not offer the same details about the product’s safety compliance.
  • Product Transparency. One of the best things about UL certifications is the ability to confirm them. UL provides an Online Certifications Directory, which includes a full list of names of companies authorized to use the UL Mark on or in connection with their products, along with the types of marks they are allowed to use.

In many cases, the UL reference number will be listed on the product packaging for easy confirmation. This means businesses can rest assured that their purchase is truly backed by UL requirements.

UL and Your Business

UL Marks are some of the best resources at your disposal for identifying quality products for industrial applications. With a basic understanding of what each mark means and what marks to seek for each particular installation, businesses can find exactly what they need.


If you need help with your industrial installation or are wondering what UL mark you need, Global Electronic Services can help. We will get your facility and pertinent installations up and running as quickly and inexpensively as possible, with an emergency repair line staffed by highly trained representatives who are available all day every day. Whether you need an installation, repair or simply some advice, you can count on us. Contact Global Electronic Services today to get started by calling 877-249-1701.

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