When it comes to components and fully designed products, there are always many questions about UL ratings. This article will cover some important information about UL (for example, which components typically have UL Recognition certificates, which products tend to have UL Listing certificates, etc.), and discuss some misconceptions about UL.

Before reading this article, it is recommended to take a look at the topic comparing UL Listing and UL Certification: The Difference Between "UL Listing" and "UL Certification" .

Manufacturers need to consider three factors when choosing UL listing or UL certification.

• The first is the application and the environment it will be used in. If the application will be used in a harsh environment, UL listed products are generally recommended because these products are tested as a whole unit.

• The second consideration is additional planning and protection when selecting components. UL-certified components may require further measures to protect against dust, water, and impact. If your planned system only requires component protection and not necessarily UL compliance, using UL-certified materials may be sufficient.

• Finally, there is the number of standards required in your design. If there are many standards that align with UL standards, it is better to use UL listed products that meet your needs rather than UL certified individual components.

The following is a non-exhaustive list of common components that may have UL certification filings:

• Single and multi-conductor wire: Some jacket materials are more flammable and UL 94 generally applies in these cases.

• Class X and Class Y safety capacitors: These types of capacitors have fairly high voltage ratings and can present a risk of fire or electric shock (sparking) if used improperly or if the device fails.

• Certain batteries: Batteries are often used in home electronics, so UL certification may apply.

• Heat shrink or other cable protection

• fuse

• breaker

• Any device specifically designed for circuit protection: for example, gas discharge tubes, inrush current limiters, surge suppression ICs, and TVS components.

• Certain power management ICs

Generally speaking, any material that is built to a high standard or provides power will usually have a UL certification.

Example:

• Gateways and routers

• Soldering Iron and Soldering Station

• Wall-mounted and benchtop power supplies

• printer

• PLC

• Circuit breakers: Some circuit breakers can be considered complete products

• VFD

• Industrial Power Supplies

Some evaluation boards and professional boards may have UL listing or UL certification documents. If you are unsure, it is best to check their datasheets.

If any component or product doesn't fit the descriptions I've discussed, it likely doesn't have UL documentation and likely never will. It turns out some materials don't even have the specifications for UL standards. Some products simply aren't designed to be safe enough to pass UL testing. For more information on UL certification, see the original article.