science

History of AC power plugs and sockets

History of AC power plugs and sockets is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand History of AC power plugs and sockets rather than just read about it. In short: Approximately 20 types of AC power plugs and sockets are in common use around the world, and many obsolete socket types are still found in older buildings. Development Early history When electricity was first introduced into houses in the 1880s, it was primarily used for lighting.

Key takeaways

History of AC power plugs and sockets belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect History of AC power plugs and sockets to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of History of AC power plugs and sockets from memory before moving on to harder problems.

Reference excerpt

Approximately 20 types of AC power plugs and sockets are in common use around the world, and many obsolete socket types are still found in older buildings.

Development

Early history

When electricity was first introduced into houses in the 1880s, it was primarily used for lighting. One common approach for other appliances (such as vacuum cleaners, electric fans, smoothing irons and curling tong heaters) was to connect to light bulb sockets using lampholder plugs. However, in Britain, there were recognisable two pin plugs and wall sockets appearing on the market as early as 1885.

British origins

As electricity became a common method of operating labour-saving appliances, a safe means of connection to the electric system other than using a light socket was needed. Thomas Tayler Smith, of London, received British patent 4162 in 1882 for an "Electric-Circuit Connection" to "enable the electric conductors conveying the current to one or more lamps, or along a flexible cord, to be rapidly and safely brought into connection with the line or main wires". Smith subsequently received U.S. patent 311,616 for the same device in 1885. According to British Author John Mellanby there were British patents for plug and sockets granted to T.T. Smith in 1883 (No. 3883) and W. B. Sayers & G. Hookham in 1884, (No. 16655). Mellanby also writes that there were two-pin designs by 1885, one of which appears in the General Electric Company catalogue of 1889. Gustav Binswanger, a German immigrant who founded the General Electric Company, obtained a patent (GB189516898) in 1895 for a plug and socket using a concentric (co-axial) contact system.

Hubbell's inventions

Several early American electrical plug and socket arrangements were invented by Harvey Hubbell. On 26 February 1903 he filed two patent applications featuring 2-pin plugs and adaptors for using his plugs with existing designs of lamp sockets and wall receptacles. Hubbell's first plug design had two round pins which differed from those already in use in Europe in that the tips of the pins had annular detents similar to those of present-day jack plugs to positively retain a plug in its socket. In one patent, U.S. patent 774,250 a plug was used with a socket which screwed into a lampholder (like the early lampholder plugs). In the other patent U.S. patent 776,326 the same type of plug was used with various three-way adaptors that could be connected to lampholders or "a receptacle of any ordinary type". Figures 2 and 4 of this patent show an adaptor plugged into what appears to be a "Chapman" receptacle. Hubbell evidently soon found the round pin design unsatisfactory as a subsequent U.S. patent 774,251 filed on May 27, 1904 shows lampholder adaptors similar to those of his first patent for use with plugs having coplanar (tandem) flat pins. Hubbell's catalogue of 1906 includes various three-way adaptors similar to those shown in the US 776,326 patent, but modified for use with the coplanar flat pin plugs. The Chapman receptacle must have been in general use at the time, as it was the only type of non-lampholder receptacle for which adaptors were supplied. The 1906 catalogue says of the Chapman adaptor: "The device avoids fastening the cords together as is necessary with the ordinary Chapman plug when used for more than one purpose." This suggests that Hubbell's original invention was prompted by his observation of the problem that arose with the use of this sort of receptacle and plug. Gradually wall sockets were developed to supplement those that screwed into lampholders. In 1912 Hubbell rotated his tandem pins by 90 degrees to arrive at the parallel flat pin configuration still widely used today (NEMA 1-15). A feature common to all of Hubbell's patented designs is the provision of detents to retain a plug in its socket. This would have been a desirable feature in the days before wall receptacles became widespread and, for many consumers, the only source of electricity was an electric light socket.

… excerpt ends here. Continue reading the full article.

Illustrations

History of AC power plugs and sockets: Early GEC 2 pin plug and socket as depicted in the 1893 GEC Catalogue — Early GEC 2 pin plug and socket as depicted in the 1893 GEC Catalogue

Worked examples

Example 1 — a first encounter with History of AC power plugs and sockets

Start with the simplest possible case. Write down what History of AC power plugs and sockets claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to History of AC power plugs and sockets before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about History of AC power plugs and sockets ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of History of AC power plugs and sockets

In research: History of AC power plugs and sockets appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses History of AC power plugs and sockets in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: History of AC power plugs and sockets is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mains power connectors, so understanding it makes those chapters shorter.
In everyday life: Look for History of AC power plugs and sockets outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study History of AC power plugs and sockets in 20 minutes

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Frequently asked questions

What is History of AC power plugs and sockets in simple terms?

Approximately 20 types of AC power plugs and sockets are in common use around the world, and many obsolete socket types are still found in older buildings. Development Early history When electricity was first introduced into houses in the 1880s, it was primarily used for lighting.

Why does History of AC power plugs and sockets matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study History of AC power plugs and sockets?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on History of AC power plugs and sockets.