Does it have the UL symbol?
A local resident checks for the UL symbol on a spool of holiday tree lights at a hardware store in Grand Forks, N.D. UL stands for Underwriter Laboratories, which is an independent, not-for-profit product safety testing and certification organization. Grand Forks Air Force Base Instruction 32-2001, Section 4.22.4. states, electric string lights and wiring shall be UL rated for their intended use and shall be in good condition. (U.S. Air Force photo/Staff Sgt. Luis Loza Gutierrez)