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Underwriters Laboratories, Inc.

Underwriters Laboratories, Inc.

333 Pfingsten Road
Northbrook, Illinois 60062-2096
(847) 272-8800
Fax: (847) 272-8129
Web site:

Nonprofit Company
Employees: 5,258
Sales: $351.5 million (1997)
NAIC: 541380 Testing Laboratories (Except Medical, Veterinary)

Underwriters Laboratories, Inc. (UL) and its subsidiaries around the world evaluate products, materials, and systems for safety and compliance with U.S. and foreign standards. In 1998, more than 14 billion UL Marks appeared on new products worldwide. The UL staff has developed more than 600 Standards for Safety, 80 percent of which are approved as American National Standards. Testing and service fees from clients support the independent, not-for-profit organization.

A Testing Laboratory: 18941904

At the 1893 Worlds Columbian Exposition in Chicago, people flocked to the Palace of Electricity. They stared awestruck at the dazzle created by 100,000 Edison light bulbs. Chicago fire insurance authorities were more concerned about the fires that kept breaking out, igniting the cheap jute covering the structure. Were they caused by the network of electric wires and hook-ups, by this new alternating current? Why were the new fire alarm systems having such problems? They turned to William Henry Merrill, an electrical inspector, to help them.

Merrill set up a laboratory near the fairgrounds, above Fire Insurance Patrol Station Number One. The labs mission was to increase fire prevention by testing new electrical devices that could cause fires and investigating everything that affected the spread of a fire. According to This Inventive Century, ULs centennial publication, the one room held a bench, table, chairs and a few electrical measuring devices purchased for the grand sum of $350. With the financial support of the Chicago Board of Fire Underwriters and the Western Insurance Association, the lab became the Underwriters Electrical Bureau.

Merrills first test was conducted on an asbestos paper used as an insulation material, which the manufacturer claimed was nonabsorbent and noncombustible. The labs report, issued on March 24, 1984, found, in fact, that the paper did absorb water, but could not be made to burn. Although not appropriate as insulation, it was fire resistant. In the labs first year, Merrill and his staff of two completed 75 tests; in the first five years, they performed 1,000 testschecking sockets, switches, wires, and a variety of supposedly noncombustible materials. In 1898 they published the first list of approved fittings and electrical devices, including flexible electrical cord and a snap light fixture. The approved products also received distinctive labels, indicating they had been inspected and certified free from reasonable safety hazards by Underwriters Laboratories. Thus was born the UL Mark.

In 1900 the lab moved into larger quarters, and in 1901 it was chartered in Illinois as Underwriters Laboratories, Inc., taking its name from its new sponsor, the National Board of Fire Underwriters. Its purpose, according to the charter, was to maintain laboratories for the testing of appliances and to enter into contracts with the owners and manufacturers of such appliances respecting the recommendation thereof to insurance organizations.

In 1903 the National Board appropriated money to build a fireproof building north of the Chicago River, which would serve as ULs home for the next 75 years. That same year, the Laboratories began fire performance testing on wire windows and fire doors, moving beyond fittings and electrical devices, and UL wrote its very first Standard, Tin Clad Fire Doors and Shutters. The companys early motto was Fire is servant, not master, and in 1904 UL approved its first automatic fire sprinkler.

Testing Consumer Products for Safety: 190526

By 1905, UL had a budget of $300,000 and had published 7,500 reports. That year, UL issued its first label for a fire extinguisher and Merrill expanded his labs services beyond simple testing of products. To ensure that the listed fire extinguisher continued to meet safety requirements, he initiated regular inspections at the manufacturers plant. That practice soon was widened to include follow-up, onsite inspection of all approved consumer products. By 1907, UL inspectors were operating in 67 cities.

The beginning of the 20th century saw the introduction of a huge variety of new electrical appliances. UL listed the Autophone, a motor-driven phonograph with a horsepower motor in 1907, and the first modern vacuum cleaner in 1909. Some inventions failed UL tests for years until one finally was safe and durable enough to meet ULs requirements. An electric iron was introduced in 1912 and became very popular. But the early models frequently started fires when the current was on. Not until 1926, after rigorous, reasonable testing of the Steam-O-Matic, which had an automatic temperature control, did UL list its first flat iron. In 1913 UL tested the first security devices and replaced the word approved with Listed and Inspected. For consumer products, UL testing focused on three basic questions: What is the shock hazard? What is the fire hazard? What is the danger of physical injury? By testing for safety, UL helped allay public suspicions and fears of electricity.

Testing Building Materials, Airplanes, Automobiles, and Other Risky Things: 190620s

The 1906 San Francisco earthquake, which destroyed 25,000 buildings, served to further expand ULs activities, as UL helped the National Board of Fire Underwriters to develop building codes. UL also helped develop early National Electrical codes, and its engineers would help establish, and its research would be used by, numerous industry councils to develop safety codes. UL sought to help determine to what standards materials should be held. In the process, its engineers explored how a fire behaved, how fast a building would burn, and what effect a major fire would have on the structure and materials. To find those answers, it created massive furnaces.

In 1907 UL began testing roofing materials, directing the flames from 36 burners on a mock-up of a complete roof and dropping red hot discs on the material. Most roofs at that time were made of wooden shingles, but in 1916 UL gave a time rating for three kinds of roofing. In 1924 tests began on a new roofing material: asphalt.

In 1910 testing began on building columns, which were becoming important factors in building construction as more of the new skyscrapers were erected. A 1919 report presented landmark findings on the effect of fire on building columns, and the following year ULs Standard Time-Temperature Curve became a U.S. standard. That curve made it possible to give a fire rating to just about every type of construction. Also in 1920, UL began testing floors and ceilings, using two new horizontal test furnaces. In 1922 UL introduced the 25-foot-long Steiner Tunnel to determine how fast a controlled flame spreads. During ten-minute tests, engineers were able to calculate the surface burning characteristics of different products, and the Steiner Tunnel set its own standard as a testing mechanism.

Twenty-two years after establishing his lab, Merrill became the organizations first president who was a full-time UL employee. This occurred when UL became self-sustaining from the income generated by the testing fees paid by manufacturers and direct support from the insurance industry ceased. Merrill quickly established industry councils for burglary protection, casualty, electrical products, and fire protection to develop safety codes.

That same year, UL went international, opening an inspection office in London to check British products being exported to the United States. Over the next 80 years, UL would open more foreign inspection offices and develop partnerships with certifiers in other countries, ensuring that products coming into the United States met U.S. safety standards.

From safety matches (1908) to gasoline pumps (1911) to auto safety glass (1914) and locks (1915) to wooden ladders (1915) and x-ray machines (1915), UL tested and certified products beyond the direct danger of fire and electricity. In the early 1920s, UL tested and registered airplanes, issuing air worthiness certificates to 35 private and commercial planes (including a seaplane). Those certificates were required to get insurance. For two years (192123) UL also registered and Marked pilots. One example from the UL Rules of the Air registered pilots had to follow was: Airplanes shall always give way to balloons and airships whether fixed or free. ULs efforts helped support the establishment of the Civil Aeronautics Board in 1923, as the federal government assumed responsibility (and regulation) of air safety.

Also during the 1920s UL engineers continued to work with automobile manufacturers to test the parts that went into cars, from headlights to fuel systems to steering wheel locks. By 1924, UL had tested 700 automobiles. In 1923 Merrill died, and Dana Pierce became president. Pierce was president for 12 years and continued to expand the organization. UL opened a lab and office on the West Coast and another lab in Illinois, which tested high explosives and toxic gases. Consumer products Listed during Pierces tenure included the first hot-water heater for home use, several coffee percolators, portable electric saws and drills, the Pianola player piano, waffle irons, and electric dishwashers, heating pads, and fans. UL also tested the first household refrigerators, issued the first radio Standard, and increased its work with electric motors and safes and vaults.

Company Perspectives:

ULs primary focus is acceptance based on integrity. To help companies function in a global market, we specialize in acceptance.

Continued Growth: 1930s60s

Alvah Small became ULs third president in 1935, and the following year UL re-incorporated as a nonprofit corporation in Delaware. Small introduced a fleet of mobile labs, using specially equipped cars, to test products in the field. In 1941 UL began formal testing of the combustibility of plastics. With the introduction of engineered plastics in 1957, this became a major research area for the organization.

During World War II, UL tested fireplace flues and vents for temporary wartime housing and developed systems for protecting windows from bomb explosions. In 1948 Curtis Wellborn was named president. He oversaw a major expansion program, opening new facilities in Northbrook, Illinois, and Santa Clara, California, and initiating new international activities. These included the testing of European-made products in testing centers in Europe with follow-up onsite inspections.

In 1954 UL won a landmark Internal Revenue Service decision upholding its nonprofit status. Although the issue continued to be raised periodically in future decades, the decision that UL was a nonprofit organization testing for public safety has not been overturned.

One area of intensive testing during the early 1950s was televisions and their imploding picture tubes. UL had received the first submittals of TVs for testing in 1939 and, after the war, many more appeared on the scene. UL worked with manufacturers to develop protective shields and glass laminates so that the picture tube glass would not shatter. Televisions also were tested for radiation, the temperature of control knobs, overheating, stability, and durability. The latter test involved putting a 50-pound weight on the top of the set and checking that the television still operated properly. TVs earned the Mark only after passing more than 45 tests.

The introduction of new types of office machines posed new safety concerns. In 1953 UL Listed the first mainframe computer and in 1955 it certified the printed wiring (circuit) board. In 1959 UL Listed the Xerox 914 copier, which churned out six copies a minute. That year, Merwin Brandon became the organizations fifth president and UL continued to grow. In 1967 UL helped establish the Consumer Advisory Council.

In the fire protection area, UL continued to monitor and inspect fire hoses, extinguishers, and sprinkler heads. It tested and Listed smoke detectors, issuing the first Standard in 1960. The organization also began certifying that fire pumpers delivered a stream of water at 1,000 gallons a minute and would not tip when a full crew of firefighters was on board. In 1985 UL again turned to a fleet of mobile labs to test aerial and ground ladders on fire trucks.

Boats and Foreign Subsidiaries: 1970s80s

UL established its Marine Department in 1970, which became the recognized testing agency for the U.S. Coast Guard. UL began testing the buoyancy and strength of life vests in 1971 and soon moved to boats, testing some 210 types of components, from hull arrangement to lights to fuel lines.

The 1970s saw the first Standard for automatic garage door openers (1973), as well as the Listing of video game systems and videotape recorders (1975), microwave ovens (1977), the personal computer (1978), and the automatic teller machine (1979). One ATM test ensured that a skilled burglar using sophisticated tools could not penetrate an ATM within 15 minutes. Also in 1979, UL Listed the electronic grocery scanner, its first effort at evaluating lasers, and moved its headquarters from Chicago to Northbrook.

During the 1980s, UL issued its 500th Standard, the first separate Standard for telephone equipment, and opened the first UL-operated inspection centers outside the United States. Its international activities continued to grow with its Far East subsidiaries, UL International Ltd. and UL International Services, Ltd., responsible for testing products in Hong Kong and Taiwan. UL also helped companies meet international quality assurance standards by introducing an ISO (International Organization for Standardization) 9000 Registration program.

An Increasingly Global Presence: The 1990s

In 1990 Tom Castino became ULs eighth president and accelerated the organizations shift from being the provider of the U.S. national product safety mark to becoming, in his words, the leading provider of worldwide product certification and management system registration services. Instead of concentrating primarily on ensuring that products coming into the United States met UL and U.S. safety standards, Castino wanted to focus on developing a high level of global acceptance so that manufacturers with plants in various countries would be able to more easily test for UL Listings and/or certification by other countries authorities.

In 1993 UL received accreditation as a certification organization by the Standards Council of Canada. Now UL could test and certify to Canadian standards and codes for products sold in Canada, not just for those exported to the United States. UL established a special UL Mark for Canada. That same year, the organization created a new subsidiary in Japan to provide more service to its Japanese customers. By 1994, more than one-third of UL activity represented work for clients outside the United States.

UL entered into strategic agreements with foreign testing and certification organizations, making it possible for UL to conduct a single set of tests after which a product could receive certification for the United States, France, Brazil, or Mexico. In Asia, the Hong Kong laboratory of UL International Ltd. gained accreditation by the China National Accreditation Committee for Laboratories, and in the United Kingdom, ULs subsidiary received accreditation by the United Kingdom Accreditation Service. In Denmark, UL bought the Danish national testing and certification organization, Demko, when the government moved to privatize state-owned enterprises. In 1998 UL organized itself on a geographic business unit basis to provide local, full service around the globe.

But the focus on global acceptance did not mean that UL had stopped its efforts at home to meet the safety demands of emerging technologies. The organization established its first U.S. subsidiary, EMC Technology Services, Inc., to address the product design phases and testing needs of electromagnetic compatibility compliance (EMC). UL built additional testing chambers and acquired C&C Laboratory, Inc., a California-based EMC testing and services company, and made it part of the new subsidiary.

In 1999 UL expanded its monitoring services to include Internet privacy, with the Better Business Bureaus hiring UL to monitor compliance with the BBBOnline privacy seal program. UL also developed a new service to test and recognize software components and worked on the development of the 1998 Standard for Software in Programmable Components, which included requirements for the functioning of operating systems and application software.

For more than 105 years, from insulation to the Internet, Underwriters Laboratories, Inc. helped to make a safer world. Despite the introduction of more complex materials, systems, and products, it continued to follow William Merrills principles: Know by test, and state the facts. Testing for Public Safety. Our only function is to serve, not to profit.

Principal Subsidiaries

UL International Ltd. (Hong Kong); UL International Services, Ltd. (Taiwan); UL International Services, Ltd. (Singapore); UL Japan Co., Ltd.; Demko A/S (Denmark); UL de Mexico, S.A. de C.V.; UL India Private Ltd.; UL International Italia S.r.l.; UL International (U.K.) Ltd.; EMC Technology Services, Inc.

Further Reading

About ULWho We Are and What We Do, Underwriters Laboratories Inc., 1999,

After ISO 9000, Electronic Business Buyer, October 1994, p. 48.

Better Business Bureaus Hire Underwriters Labs, American Banker, August 18, 1999, p. 18.

Bezane, Norm, This Inventive Century: The Incredible Journey of Underwriters Laboratories 18941994, Northbrook, 111.: Underwriters Laboratories Inc., 1994.

Flock, Jeff, UL Safety Labs Celebrates 100th Anniversary, Cable News Network, Transcript #211-4, March 26, 1994.

Ritter, Jim, Test Fires Help UL Plan for the Real Thing, Chicago Sun-Times, October 8, 1996, p. 11.

Sutton, Larry, Safety Stamp Born in L.I. Lab, Daily News (New York), December 15, 1996, p. 1.

UL Acquires Danish Demko, Flame Retardancy News, August, 1996.

UL Launches Software Component Recognition Program, M2 Presswire, August 10, 1999.

A World of Difference Between UL Listed and UL Registered, Code Authority, Underwriters Laboratories Inc., 1997,

Ellen D. Wernick

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Underwriters Laboratories (UL)

Underwriters Laboratories (UL)

Underwriters Laboratories (UL) is the largest and best known independent, not-for-profit testing laboratory in the world. Based in Northwood, Illinois, UL conducts safety and quality tests on a broad range of products, from fire doors to CCTV cameras. The laboratory provides a full spectrum of conformity and quality assessment services to manufacturers and other organizations. It also assists jurisdictional and provincial authorities, offers educational materials to consumers, and works to strengthen safety systems around the world.

UL provides comprehensive diagnostic testing services in the following areas: fire testing; medical device testing; EPH services (food service equipment, drinking water certification, plumbing equipment); audio/video; home electronics; Source Verification and Inspection Services (SVIS); electric vehicle components and systems; EMC testing and certification; information technology equipment (ITE) industry services; and telecom industry services. It conducts tests on products in these areas to see whether they meet standards set by UL engineers in conjunction with input from manufacturers and product users, but it will also test products to see whether they meet standards set by outside entities, such as a city (in the case of building codes, for instance). In 2005, UL conducted 97,915 product evaluations in 62 laboratory facilities that it operated around the world. As of 2005, there are 20 billion products that carry the UL Mark.

In addition to its work in the U.S. market, Underwriters Laboratories maintains services for companies looking to test products for international markets. This division of UL studies international product certification standards, assists clients with the application process, helps with correspondence and translation, and can coordinate the exchange and review of test data. In order to increase its efficiency in these international realms, Underwriters Laboratories has also launched a sustained effort to establish common standards for safety requirements, testing protocols, and certifications around the world. The impetus for this effort, according to UL, is a recognition that companies seeking to establish a presence in multiple overseas markets sometimes need as many as 20 separate safety certifications for a single product, a requirement that "can cost as much as $8,000 per safety mark per product. Many companies have annual certification budgets of $5 million or more." UL hopes to first establish common standards between the United States and Canada, then turn its attention to other markets.

UL Designations

"Underwriters Laboratories, which has been in existence for more than 100 years, is very sensitive to the prevalent but mistaken belief that it approves products," wrote Robert C. Cook in Security Management. "The only entity that can actually approve or reject a product is a federal, state, or local government agencyknown generally as the 'Authority Having Jurisdiction' or AHJ." However, an AHJwhether it is a local health code inspection department or the federal Occupational Safety and Health Administrationoften requires products to be tested by Underwriters Laboratories or another lab before the agency will approve its use.

UL hands out one of three different designations to products that pass its tests: UL listed, UL recognized, or UL certified. Businesses should note that there is no such designation as "UL approved"; companies that mistakenly tout their products with such a designation will arouse the ire of Underwriters Laboratories, which will insist that the company clarify the matter immediately.

UL Listed. This designation means that the tested product meets the laboratory's standards and can be used by itself.

UL Recognized. This designation is granted to equipment components that are used in combination with other pieces of equipment to create a finished product.

UL Certified. This designation is used by UL when it has been successfully tested to the standards of an outside authority, such as a city's building code requirements.

In 2000 UL announced its intention to transition to usage of Standard Technical Panels (STPs) in its development of diagnostic processes. The STPs will include representatives from consumer protection organizations (such as the National Consumer League), manufacturers, industry trade associations (like the Association of Home Appliance Manufacturers), and regulatory authorities (including government agencies like the Consumer Product Safety Commission). According to UL, these forums will work together to establish consensus opinions on diagnostic standards and will vote on proposed standards before they are adopted.

Businesses considering enlisting the services of Underwriters Laboratories (or similar labs) should be aware that testing can be both expensive and time-consuming. Bills of several thousand dollars per product tested are not unusual in many industry sectors, and the testing procedures usually take about six months to complete, with some tests extending well beyond that time frame. But the importance of UL acknowledgment is very significant to marketplace image in many industries.


Cook, Robert C. "A Tale of UL Testing." Security Management. July 1995.

Jancsurak, Joe. "New Standards for Standards." Appliance Manufacturer. August 2000.

Strom, Shelly. "Underwriters Laboratories Gives Seal of Approval." Business Journal-Portland. 4 August 2000.

"The Underwriters Labs' Faster Seal of Approval." Business Week. 20 December 1993.

"Underwriters Labs Pursues Single Worldwide Standard." Manufacturing News. 25 August 2000.

Wingo, Walter S. "A Boom Time for Product Testing." Design News. 9 March 1992.

                              Hillstrom, Northern Lights

                                updated by Magee, ECDI

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