UL Listed vs. UL Certified (or Recognized) Industrial Electronics

The electronics world knows “UL” stands for excellence, but do you as a product maker or OEM buyer know its true definition(s) and impact?

UL (which actually stands for Underwriters Laboratories) Solutions is the world’s top electronic product safety and certification agency. For example, the UL 508A certification for control panels verifies that the products have passed stringent safety requirements. 

Gray areas exist around UL distinctions and regulations. Some sellers, and even buyers, throw around “UL Certified” in reference to electronic products. Then there’s the UL Listed and UL Recognized labels.

The distinctions are important because they affect how a product or component can be used and what extra steps might be necessary for safety. Let’s prepare you so that you can:

• Clarify compliance and safety requirements
• Put the right components and products put into your operation
• Improve communication of your needs to the manufacturer
• Make overall better purchasing decisions
  
  

What Does UL Listed Mean?

The UL Listed designation signifies the product has passed UL’s safety tests for use in most environments. This label generally refers to finished, standalone products or systems for direct use by consumers or in industrial settings as part of a larger system.

UL Listed products are marked with a famous symbol you’ve probably seen on consumer goods with an external power supply. Common UL Listed goods include:

• Heaters & furnaces
• Electrical appliances
• Computer equipment
• Smoke & CO₂ detectors

The method of testing is the main point of difference between Listed and Recognized. UL only lists products for which it can test and verify performance of the specific function, in its exact end-use environment. 

Wondering how to get UL listed? A product has to pass testing in:

• Insulation (materials, barriers, etc.)
• Grounding (general, terminal size, circuit conductors, etc.)
• Corrosion protection
• Live part securement/support

UL Listed status is tougher to attain because it involves more testing. The UL Listed label creates peace of mind, more accountability for accidents, and a sense of protection that products without the certification don’t provide. 

Application scenarios for these products include:

• Indoor use: The ability to protect from falling dirt, water, noncorrosive liquids, airborne contaminants, and splashing or seeping oil and coolants. 
• Indoor or outdoor use: Protection against falling dirt, windblown dust, rain, temporary submersion, and the formation of ice. These tests also determine if the product will continue operation while covered in ice or exposed to hose-directed water.
  
  

What Does UL Recognized Mean?

Instead of the big picture, UL Recognized status focuses on the smaller things in industrial life. UL Recognized credentials specifically apply to components that are typically part of a larger, UL Certified electronic device.

You can spot UL recognition by the backward “RU” marking on the component. However, the general public will rarely see this label.

Recognition in this case indicates the component has been tested and approved for use in specific conditions or within certain parameters – but not as-is. When using UL Recognized components, the buying manufacturer must still perform additional testing to ensure the complete system or product meets UL standards.

For UL recognition, testing is done on various internal parts for products. These can include: 

• Wires & cables
• Connectors & terminals
• Transistors
• Pressure controllers
• Power supplies
• Display technology
• Diodes
• Mass flow controllers
• Circuit boards

Even on the inside, safety matters. If an inspector seeking the cause of a fire discovers a non-UL internal panel component (i.e. circuit breaker), it could result in you losing your insurance claim.

What Does UL Certified Mean? | Control Panel Manufacturing

There’s a lot of confusion about control panels and other assemblies carrying “UL Certified” marketing lingo. 

UL Certified is a broad term meant to indicate a product has met the safety and quality standards of Underwriters Laboratories. It does not specify a detailed scope of certification like UL Listed and UL Recognized do.

Note that the placement of a UL Certified sticker on a device doesn’t guarantee the safety of the entire assembly. It could simply apply to the enclosure.

In a way, you should view UL Certified status at the manufacturer level. Because certification is about the intrinsic safety of the broader system, it’s on the panel buyer to verify that each component is UL Listed or Recognized for an application. 

Referring to a Panel Manufacturer as Certified

A more specific application of the “UL Certified” term is in control panel building. A UL Certified panel manufacturer operates a shop that’s certified to build to UL 508A standards. 

What’s that mean? UL 508A verifies that panels meet the highest standards of protection against fire, electrical, and other industrial hazards. This reduces liability for industrial facilities in case of an incident and ensures the facility meets standards set by other regulatory agencies such as OSHA. UL 508A indicates to customers and inspectors alike that the panel has undergone rigorous testing.

However, that does not mean every panel the shop puts out is UL-approved. Around 80% of panels sold by UL 508A-certified shops or contractors are not certified.

To make sure you’re working with a capable panel shop, ask:

• Can you construct panels according to UL standards?
• Are the components used UL Recognized for this specific application?
• Do you have on-site verification steps in place to uphold safety standards?
  
  

Is UL Necessary for Your Industrial Electronics?

UL Certified is a broader term than UL Listed. Because of this, manufacturer websites, Amazon listings, and seemingly everywhere else in between muddy the terminology. Sometimes you’ll see it written as UL Listed, UL Recognized, and even UL Classified.

There’s no law on the books requiring products sold in the U.S. to be labeled, whether by UL or another recognized lab. However, the safety standards that most companies follow are the ones outlined by UL.

There are several industries, however, that require certification by a recognized lab on products that fall within the purview of certain safety codes. Retailers, therefore, prefer to sell UL-Listed products, which means manufacturers seek this approval to facilitate product sales. 

On the consumer level, these industries range from:

🚀 Aerospace
⚡ Energy
🛍️ Consumer goods
🚗 Automotive

If you sell products or require panels regularly within one of these industries, UL best practices can keep your workers and buyers safe and satisfied.

On the panel level, applications that demand UL quality include:

• Manufacturing & industrial
• Data centers
• Energy & utilities
• Transportation

However, you also carry a degree of accountability. Again, if you want a UL-approved panel, you need to specify that in your RFQ. You’re also responsible for:

• Proper installation, maintenance, and operation within its intended use and environment
• Any modifications after purchase
• Documentation
  
  

UL-Listed vs. UL-Certified (and UL-Recognized) | Final Thoughts

Different types of equipment and controllers may require unique UL labels. This speaks to the complexity of UL standards and the need for expertise in navigating them.

Specific to control panels, responsibility for UL 508A certification and adherence primarily falls on the manufacturer. It must design, assemble, and test the panels using UL Listed components, following proper wiring practices, and adhering to specific construction criteria. Don’t forget your own responsibilities during and after the sales process.

In other words, education and preparation are key. To learn more about designing and speccing a UL-friendly industrial panel, download our free e-book: