August 1955 Popular Electronics
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
Underwriter's Laboratory (UL) is an entity that seems
to have been around forever. A lot of people - maybe most people - assume that it
is a government entity. In fact, it is a non-profit organization sponsored by the
Board of Fire Underwriters (later changed to American Insurance Association,
APCIA). Its roots are traceable back to the Chicago World's Fair in 1893. Concern
over the potential fire hazard of Edison's light bulbs was the impetus for the effort.
Another aspect of the UL that a lot of people don't know is that the UL label of
approval is no guarantee that the device works properly, only that is passes standards
of safety as it relates to fire hazards. This article in the August 1955 edition
of Popular Electronics magazine gives a brief history.
Behind the U.L. Label
Television sets are subjected to a thorough going-over by Underwriters'
Laboratories. Inc. engineers. Special attention is paid to shock hazards and to
overheating problems. Cabinets are pounded and safety glass hit with steel balls
An enclosed heavy-duty switch is tested in one of U.L.'s many
laboratories. Equipment such as this is operated repeatedly under excessive loads
before it is approved and given the U.L. label. It is important to point out that
U. L. approval does not guarantee quality of performance. The testing is concerned
primarily with the safety aspects of equipment. Thus, the label on an approved radio
receiver, for instance, does not imply that it will perform better than one not
so approved. It does mean, though, that the chance of setting a house on fire is
negligible if the approved model is used.
Automatic flatiron is dropped four times during continuous operation
test of 500 hours. Temperatures of various parts as well as operation of the thermostat
are also checked.
These are only a few of the authorized labels used by U.L. to
designate approved equipment. An item bearing such a label has met specifications
and passed severe tests.
By E. D. Morgan
Equipment is tested, dropped, pounded, and burned before it is rated as safe
and tagged with the Underwriters' okay.
A familiar sight on much electrical and electronic equipment used today is an
Underwriters' Laboratories label. Exactly what is implied by the use of this label,
however, is often misunderstood.
Underwriters' Laboratories, Inc. is a non-profit organization sponsored by the
National Board of Fire Underwriters. Its function is to test and inspect materials
and equipment to prevent loss of life and property from fire, crime and casualty
hazards. To do this adequately, it subjects devices to grueling tests. Only the
hardiest designs survive and earn the right to the coveted label of acceptance.
No conceivable method of testing is overlooked. Much of the test equipment is
of U. L.'s own design and they dream up diabolical plans to subject samples to the
meanest treatment possible. They try to anticipate all of the mistakes that could
be made by a consumer. Appliances are left on for weeks and electric heater cords
are twisted and untwisted thousands of times.
Television cabinets get a thorough pounding before they receive U. L. approval.
A large picture tube can be a deadly weapon when broken, as it hurls tiny fragments
of glass in all directions. To insure against injury, the safety screen on the front
must be capable of withstanding such shattering. A pound-and-aquarter steel ball
is hurled at the set to determine its fitness for this purpose.
Electronic equipment is often used by U.L. technicians. Here, the split-second
operation of a burglary detection system is photographed. Accuracy is assured by
using a cathode-ray oscilloscope, a beat-frequency generator, and various meters.
To determine whether a safe is fireproof and burglar-proof, U. L. employs its
own staff of "arsonists" and "safecrackers." These men are masters at their trades
and tackle a new item with drills, sledges, torches, and explosives. Just to make
sure, the safes are dropped onto concrete from a second-story level, then placed
in a 2000° F furnace for an hour or so. If the internal temperature goes high enough
to turn valuable papers brown, what is left of the safe is returned to the maker
Fire doors are tested in large gas furnaces where flames lick at them until they
are red-hot. Then a fire hose is intermittently played on the other side of the
door. Acceptable fire barriers must pass the fire endurance as well as the hose
U. L.'s Growth
The organization had its unique start when bulbs were installed at the first
Chicago World's Fair in 1893. These became the Fair's chief attraction - as well
as its greatest hazard. Fires, started by the not-yet-perfected lamps and wiring,
were commonplace. This led a group of New England insurance interests to authorize
William H. Merrill, a young engineer, to investigate the situation. He responded
to each fire alarm at the fairgrounds. If the cause were electrical, he would try
to locate the defective device and determine why it failed.
Because of Merrill's insistence on thorough testing before the lamps were installed,
and correcting their faults before offering them to the public, Underwriters' Laboratories,
Inc. was born the following year. Merrill was its first president.
Since then, U. L. has mushroomed. Over 375,000 products have been found acceptable
under its rigorous standards. Testing laboratories are located in Chicago, New York
and San Francisco, with representatives in nearly 200 cities insuring that the standards
are upheld at the factories. The work is financed solely by charges made to manufacturers
for the inspection of their equipment.
Annual lists are published giving the manufacturers' names and their approved
products. Four main lists are prepared which cover: electrical equipment; fire protection
equipment; gas, oil and miscellaneous appliances; and accident hazard, automotive
equipment and burglary protection.
Good will and impeccable honesty is the main stock-in-trade of this organization.
U. L. never solicits business, but industry has learned that it is well worth the
effort to make sure its products deserve the U. L. label.
Posted August 26, 2011