Underwriters Laboratories has been doing business since 1894 when its founder, William Henry Merrill, opened the Underwriters' Electrical Bureau of the National Board of Fire Underwriters, notes UL.com. The first test conducted by Underwriters Laboratories was on a non-combustible insulation material for its first customer, Mr. Shields. By 1895, the company had three employees and had issued 75 reports to its customers; its annual budget was $3,000.
By 1899, Underwriters' Electrical Bureau had indexed 1,000 lab reports on cleats, circuit breakers, arc lamps, bushings, fire alarm boxes, fuses and heaters. It also had reports on flexible cords, rheostats and lamp adjusters. It published "Tin Clad Fire Doors," its first Standard for Safety publication, in 1903.
In 1907, the company certified the first motor-driven phonograph, which was followed in 1909 by a motor-driven cash register, light shield for moving pictures and vacuum cleaner. The company opened its first international office in London in 1916.
By 1960, UL had published its first Standard for Safety for smoke detectors and built its fire protection laboratory. It issued its 500th standard in 1985 for telephone equipment. As of 2015, the UL mark appears on billions of products around the world and is considered a mark of excellence, states UL.com.