Understanding UL Certification for Electrical Components

When it comes to electrical safety in the U.S., one name stands above the rest—UL. UL stands for Underwriters Laboratory (now UL Solutions), originally founded as the Underwriters Electrical Bureau by William Merrill Jr. after the Chicago Underwriters Association decided, together with the Western Insurance Union, to support his idea for an electrical testing laboratory. Its roots lie in the efforts of fire underwriters to assess fire risk and improve product safety. UL has built a reputation for establishing nationally recognized safety standards in the U.S.

Short for Underwriters Laboratories, UL is a globally recognized safety organization that sets the standards for how electrical components are tested, marked, and approved. UL evolved from an electrical testing laboratory focused on developing and maintaining nationally recognized safety standards. Whether you’re a manufacturer, contractor, or sourcing agent, understanding UL certification is not optional—it’s essential.

​In this blog, we’ll break down what UL certification is, what it covers, and what you need to know to stay compliant and competitive.

UL electrical certification means a product has been tested by UL (Underwriters Laboratories) and meets specific safety standards. These tests cover electrical shock risks, fire hazards, and even mechanical failure.

UL doesn’t manufacture anything. Instead, it acts as an independent third party that checks products for safety. If a product passes, it gets the UL mark—a symbol that tells buyers, inspectors, and regulators that the product has been properly vetted. The UL mark is a certification mark that signifies the product has met rigorous safety standards.

For manufacturers, this certification can make or break a product’s ability to enter certain markets or pass inspections. For consumers and businesses, it offers peace of mind. Certified products help ensure consumer safety and demonstrate compliance with regulatory requirements.

​Obtaining UL certification helps manufacturers mitigate risk and deliver confidence to customers and regulators.

UL offers several types of UL certifications, depending on how a product is made and used. UL certifications include UL Listed, UL Recognized, and UL Classified, each with its own certification mark.

UL Listed certification is indicated by the UL Listed symbol or UL Listed mark, which appears on consumer-ready products. This mark signifies that the product has undergone extensive testing for safety, longevity, and performance as a stand-alone item.

UL recognized certification, also known as UL recognition, applies to individual components within larger systems, such as machinery or factory equipment. UL recognized certification is indicated by the UL Recognized Component Mark or component mark, and UL recognized stamps are used to show that these components meet specific safety standards. Unlike the UL Listed mark, the UL Recognized Component Mark is not used for finished products but rather for parts intended to be integrated into larger assemblies.

​When reviewing the symbols and requirements, it is important to distinguish between the UL Listed mark, which is for fully certified consumer products, and the UL Recognized Component Mark, which is for components within larger systems.

This is the most common. It means the product meets safety standards for its intended use. UL Listed certification is indicated by the UL Listed symbol, UL Listed mark, or UL Listed logo, which appear on products that have undergone rigorous testing. Products with the UL Listed seal or UL label have been tested to ensure they are free from reasonably foreseeable risks of electric shock. Common products with UL Listed certification include fire extinguishers and smoke alarms, which are essential for consumer safety. The presence of the UL logo on a product signifies it has undergone rigorous testing and meets industry safety standards. You’ll see this on things like power strips, circuit breakers, and wiring harnesses.

Used for components rather than full products—think switches, relays, or internal wiring. These parts are tested for use inside larger assemblies. UL recognized certification is indicated by the UL Recognized Component Mark or component mark, and UL recognized stamps are used for components within larger systems. Common UL recognized components include circuit boards and power supplies, which are tested during the manufacturing process to ensure safety and efficiency. Using UL recognized components can help companies implement more sustainable practices in their manufacturing process, supporting safer, greener, and more sustainable practices overall.

These products are certified for specific hazards or performance claims. UL Classified is a type of product certification focused on certifying products for particular hazards or performance attributes. For example, a fire-rated electrical panel might be UL Classified for flame resistance but not for other safety standards. Certifying products for functional safety is especially important in applications where system performance and risk mitigation are critical.

Less common in electrical but used in data cabling and communication systems. It means UL tested the performance to make sure it meets certain benchmarks—not just safety. This type of certification can also be considered a form of system certification, as it evaluates the performance and compliance of entire systems rather than just individual components.

​Each certification level has its own symbol and requirements. Using the wrong one—or faking a mark—can lead to major consequences.

UL has written thousands of individual standards, but some are more important to wire harnesses and electrical components than others. These standards are considered applicable standards and industry standards for electrical components, and UL's safety standards are recognized as nationally recognized standards in the U.S. and Canada. They outline how products are built, tested, and labeled.

​Here are a few key UL standards:

These standards go deep. They cover everything from dielectric voltage withstand tests to crush resistance. If you’re in wire harness manufacturing, working with a UL-certified assembler ensures your product meets these safety benchmarks right from the start.

These two standards are often confused, but they serve different purposes. Both UL 508A and UL 891 are referenced in regulatory requirements and are used by inspectors to verify compliance and confirm compliance with safety standards.

This standard is about the design, construction, and labeling of control panels used to operate machinery or systems. It covers issues like overcurrent protection, spacing between components, and wire routing.

​If you’re making or buying a panel that controls motors, fans, or industrial equipment, UL 508A is the one to follow. Personnel certification may also be required for those installing or maintaining UL 508A certified control panels, as it validates practitioners' skills and qualifications to ensure safety and compliance.

UL 891 applies to switchboards used in commercial and industrial power distribution. These are big electrical panels that distribute large amounts of power inside a building.

They require a higher level of testing because they handle higher voltages and currents—think 480V and above.

​Bottom line:

Using the wrong one? That’s a recipe for failed inspections or dangerous installations.

No—but many should be.

​UL certification is not required by law in most cases. However, it often becomes mandatory because:

While it’s technically legal to sell some products without UL certification, doing so can limit where and how you can sell. Plus, skipping certification exposes you to liability if something goes wrong.

​If you’re unsure whether your product needs UL, it’s best to consult with a compliance expert—or better yet, work with a contract manufacturer that understands the rules and handles it for you. Working with experts can help you identify regulatory gaps and ensure your business processes meet applicable standards for UL certification.

UL certification isn’t permanent. Once a product is certified, it still needs to be made exactly the same way it was during testing.

​A few things that can void a UL mark:

UL performs unannounced factory audits to make sure manufacturers are following the rules. If you get caught making changes without retesting, UL can pull your certification—and you may have to recall products already in the field.

​That’s why many top manufacturers use UL-certified wire harnesses and components—they don’t want to risk downstream failures or voided marks.

In the United States, there’s no single required electrical certification from the federal government. However, most local jurisdictions use the National Electrical Code (NEC) as their guideline. The NEC often references UL standards.

​Because of this, the following are commonly “required” by code inspectors, building departments, and AHJs (Authorities Having Jurisdiction):

UL certification is also important for building materials and food safety equipment, which must meet specific safety standards to ensure regulatory compliance.

​Other certifications—like CSA (Canada), ETL, or CE (Europe)—may also be accepted in some areas, but UL is the most widely used and trusted in the U.S.

Yes, but it’s risky—and often short-lived.

​Here’s what happens when you skip UL:

If you’re selling direct-to-consumer online, you might get away with it temporarily. But you’ll face chargebacks, negative reviews, and compliance takedowns if something fails or injures someone.

For B2B manufacturers, skipping UL is usually a deal-breaker. OEMs, facility managers, and engineers know what’s at stake. If your product isn’t marked, they’ll move on.

​UL certification isn’t just about safety. It’s about trust, credibility, and access to markets. Obtaining UL certification can also help ensure brand loyalty by showing your commitment to safety and quality.

UL certification is more than a stamp on a label—it’s a signal that your product was built the right way and won’t cause problems down the line.

Whether you’re sourcing wire harnesses, designing a control panel, or building an entire electrical system, UL standards help protect your business, your customers, and your reputation.

If you’re unsure how UL fits into your supply chain, partner with a contract manufacturer who understands it inside and out. At Sterling Technologies, we build to UL standards every step of the way—because safety isn’t something you leave to chance.