UL588 has traditionally covered Decorative Lighting Strings limited to an installation and use not exceeding 90 days. In recent years, there has been increased interest and popularity of string lights used year-round for decoration or illumination on a patio and other outdoor gathering places.

Since these products are not intended for task lighting and are used and wired similar to other parallel-connected lighting strings currently covered under UL588, it made technical sense to also cover these string lights under UL588. String lights are defined as follows: A parallel-connected string of discrete lamps interconnected through lengths of cord, and terminating in an attachment plug. The string lights are permitted to be optionally provided with a load fitting (cord connector), a controller, or other features as described in the standard.

Series-connected string lights are not included in this revision of UL588 based on the similarity to lighting strings currently covered under UL588 that are limited to seasonal and holiday use and the potential risk of confusion in the market and possible misuse of seasonal-use lighting strings.

As all-year use string lights are intended for a longer installation and use than previously permitted by UL588, additional requirements addressing this use were developed. These additional requirements include increased minimum American wire gauge (AWG) size and insulation thickness of the wire, additional flexing, more rigid strain relief testing and different safety instructions and markings.

Consensus on the new requirements was reached by the UL588 Standards Technical Panel (STP) and was published September 15, 2017. To distinguish these products from Seasonal Use Lighting Strings, a new category, “String Lights for All-year Use,” was created under DGZW.

For questions regarding this update, please contact Anthony Tassone at Anthony.T.Tassone@ul.com.