Most products destined for commercial, consumer and industrial applications require some sort of certification. Underwriters Laboratory and its UL Mark are highly recognized in North America and the rest of the world. The UL Mark and its variations are often the subject of questions relating to wire and cable products. In this Wire Wisdom, we look at what it takes to be able to use the UL Marks. More specifically, we look at the value that UL’s Follow-Up Services brings to users.

Certification Providers Serve Important Roles

Certification service providers typically offer a broad array of services including, but not limited to, engineering evaluation, testing, and inspections of products and systems that are sold into nearly all industries and applications globally. Without certified products, it would be difficult to standardize on electrical and electronic systems. Lack of standardization could result in serious issues with compatibility, safety, reliability and efficiency. The services and corresponding certification marks, often called “listings” and offered by certification providers, are part of a complex supply chain. The goal of the supply chain is to supply products that are safe when used as intended.

How Certification Programs Work

Many certification providers offer product certification and listings through testing, factory inspections and engineering design reviews. Typically, a product manufacturer determines that a particular product certification is needed in order to fulfill regulatory or customer requirements. The manufacturer then searches for a certification provider that can evaluate the product and provide a certification or listing mark that can be applied to the product(s). Once the certification provider completes the evaluation phase, it will then grant use of the appropriate marking to be applied to the product(s) and the manufacturer can then begin to sell the product with the new certification.

Here’s an example: the NEC (National Electrical Code) requires cords to be listed by a NRTL (Nationally Recognized Testing Laboratory) if they are to be used in certain applications. It’s important to note that certification providers are also often identified as NRTLs. In this case, one of the most common standards to which portable cords are listed is UL Standard 62 (i.e., UL 62). Sometimes, the certification provider is also the author of the standard that the product will be certified to, as is the case when someone has UL certify a portable cord to the UL 62 standard. In this example, UL not only authors or contributes to the development of the standard, it also tests and inspects manufacturers’ product to make sure they meet the standard. There are certification providers and NRTLs other than UL, and their certification programs may be slightly different. Most providers use product evaluation, testing and inspection as part of their certification program. Providers often include inspections of the manufacturing, testing and shipping facilities as part of their certification programs. However, ongoing inspections are something that not all certification providers offer.

Why Follow-Up Services is Important

Ongoing inspections are a way for the certification provider to audit the manufacturer to make sure the certified product is still made according the original design for which it was certified. If the certification provider identifies that the products are being produced outside the limits allowed by the original certification, there are a number things that can be done to protect the user/consumer of the product.

There are other systems of quality that can accomplish goals similar to UL’s Follow-Up Services program using different methods. Such quality systems are often employed in industries such as automotive and military supply. Even though nothing is foolproof, ongoing inspections and audits of processes and systems is a time-tested method of improving product quality. The advantage to users of products bearing the UL Mark is that the auditing process used in UL’s Follow-Up Services will help to increase the consistency, quality and the safety of the product they are buying.


This document was prepared by Anixter Inc., which is not affiliated with UL. UL is not responsible for the content of this publication.


Wire Wisdom by Anixter