Before industrywide standardization came along to internationalize electrical nomenclature and specify ranges for manufactured tolerances of electrical components, manufacturers likely created their own ingress-protected plugs and sockets for consumers who needed protection from water and dust.
A Brief History of IEC and IP Ratings
In the late 1870s, electrical inventors, scientists and engineers had already understood for some time that a common electrical nomenclature needed to be standardized if electrical products made in industrialized countries could be exported to other industrialized countries. At the time, a mix of nomenclature for measurements and ratings for an influx of components were slowing the advancement of electrical products worldwide.
When the International Electrical Congress convened in St. Louis at the World's Fair in 1904, numerous exhibits inside the Palace of Electricity demonstrated various voltages whether direct current (DC) or alternate current (AC) and various frequencies. Today, predominantly two frequencies are used worldwide (50Hz and 60Hz) and rarely is “frequency” found in an agency’s standards, whereas amps and voltages are prevalent there.
Subsequently, in London in 1906, the International Electrotechnical Commission (IEC) was founded with Sir William Thompson (Lord Kelvin) named as its first president. Representatives from the United States, Austria, Belgium, Canada, France, Germany, Great Britain, Holland, Hungary, Switzerland, Spain, and Japan participated. Denmark, Norway, and Sweden were also members of the commission but were not present at the meeting.
From a page of the commission’s original document: ". . . steps should be taken to secure the cooperation of the technical societies of the world by the appointment of a representative commission to consider the question of standardization of the nomenclature and ratings of electrical apparatus and machinery." The new commission now had its anvil to hammer out international standards that would simplify electrical component trade between nations. In 1906, electricity and its components were on the move, and much of society was eager to have both in their homes.
Seventy Years Later . . .
It wasn’t until 1976 that the IEC published its first ingress protection ratings (Technical Committee 70) in the IEC 60529 standard, which explains the numeric degree of protections on a scale from “X” meaning no protections to “9k” meaning protection from powerful, close-range and high-temperature jetting water. The committee’s initial draft was hammered out in Stresa, Italy, in 1971, the second in Zurich in 1972, and the final draft in Paris in 1974 before its ratification in 1976.
One of the main reasons for the IP-rating system was to verify the claims of manufacturers that their electrical components were as waterproof as they claimed—e.g., outlets, inlets—to ensure consumer safety, but prior to the commission’s founding there were few if any independent agencies. In other words, engineers, purchasers, and consumers needed to know exactly what they were buying.
