Join us in our series of blog posts as we explore why UL listed parts do not automatically make a cord UL listed (this post), the anatomy of a UL cord (which standards cover which components), and finally, what a cord must survive to become UL listed.

Does a Cord Made from UL Components Count as UL Listed?

The plug is UL. So is the jacket. The connector has the mark as well. It would be reasonable to assume that the finished product is UL listed, but the math is not so simple. UL certification is not an additive process, inherited from construction with UL listed parts. There is a difference between component listing and finished product certification.

UL Logo

What Does “UL Listed” Actually Mean?

A UL mark on a component means that that component has been evaluated against the requirements that apply to that part in isolation. It does not mean that UL has evaluated every possible combination of usage with other UL components. For example, as we explored in the recent post about C18 power cords, the C14 plug and C7 connector may both be UL, but put them together and the end result is a cord that does not live up to the UL standard because there is a requirement in UL 817 that if the plug has a ground, so too must the connector. UL certification applies to a specific configuration, not just a combination of approved parts.

Why Does Assembling a Cord Create New Questions?

UL certification is more than just the sum of the parts. While UL listed components are a pre-requisite for overall UL acceptability, combining components creates new questions that can’t be answered by looking at each component individually. For example, are the components compatible? Is the assembly wired correctly? Does the final product pass the required tests? Has the organization been audited by UL?

What Is Required for a Cord to be UL Listed?

A UL cord must be tested to make sure it is electrically sound. Polarity and continuity, dielectric voltage withstand (also known as Hi-Pot testing) and pull tests are some of the rigors that a cord must endure to be UL listed.

Additionally, the organization assembling or molding the cord must be audited by a UL inspector to make sure that the processes and end product are living up to the standards. A cord assembled in the field cannot be UL listed even if mechanically identical to a cord assembled in a UL plant.

A manufacturer of a cord has a UL file number sometimes referred to as an “E number” which is an identifier that starts with E and is followed by 5 or 6 digits. For example, StayOnline’s E number is E250704 which is visible on every product we mold in the United States. You can search for the origin of a product by using the UL Product iQ search tool.

Why Does it Matter?

Procurement specifications may require a UL Listed cord but just because all of the individual components have the familiar UL mark, the entire cord set may not actually be UL listed. The configuration must be valid, the cord must be tested, and the organization must be audited in order for the finished product to be truly UL. While seeing the UL mark on the individual components is a good starting point, be sure to ask the right questions such as what is your UL file number and is the finished product tested.

For more information, you can reach us at 888-346-4688 or by email at sales@stayonline.com.