Anatomy of an electrical outlet

Recommendation points

• History of electrical outlets
• Electrical outlet design
• Types of electrical outlets used in different countries
• Choosing an electrical outlet
• Self-installation of electrical outlets

In this article: how electrical outlets came to be; how electrical outlets are arranged; what types of power outlets are there; how to choose sockets; how to determine and calculate the amperage for an electrical outlet; how to install an electrical outlet yourself.

Our houses and apartments are equipped with several types of communications, equipped with reliable doors, electrical equipment, glass units impenetrable to street noise and dust – safety and comfort are guaranteed. However, without these devices, simple in design, the level of comfort will be far from complete, it is not for nothing that a couple of decades ago the layout of furniture in apartments and houses depended on their location. An electrical outlet is a device familiar to everyone, a plastic square or a circle with two holes for a plug. But the correct operation of household appliances and the condition of all electrical wiring depend on the correct choice of electrical outlets.!

History of electrical outlets

A century and a half ago, electricity was used only to illuminate streets and houses. Competition between electricity suppliers led to a significant reduction in tariffs for household electricity consumption, which aroused interest among manufacturers of household appliances – the first were electric fans and vacuum cleaners, which appeared in 1890, then the list of manufactured household electrical appliances grew to a hundred. The problem was that any of these electrical appliances were connected directly to the mains, i.e. it was impossible to turn off and put household appliances into the pantry, as we are doing now with a vacuum cleaner.

In 1904, American inventor Harvey Hubbel received a patent for the first electrical outlet. It should be noted that his invention had little in common with modern electrical outlets: the Hubbel socket was screwed into the bulb holder and, in fact, was an adapter – the bulb was unscrewed, a socket was screwed in its place, to which an electrical appliance was connected through a plug. The very idea of ​​such a plug-in adapter belonged to Thomas Edison, who “borrowed” it from his main competitor Nikolo Tesla – but Hubbel was the first to get a patent. Its plug-in adapters enjoyed widespread popularity in the United States until 1920-25..

Initially, all the sockets were only external – they were placed on the wall, i.e. holes in the wall for them were not cut.

The euro socket in its almost modern form was created in 1926, invented by the German engineer Albert Büttner. In Europe, this type of electrical outlets and plugs is known as the Schuko system – an abbreviation for the German name “Schutzkontakt”, translated into Russian “protective contact”. And the first socket and plug with grounding were invented by the American Philip Labre in 1927. The idea of ​​a double socket, i.e. designed to connect two plug-plugs at once, appeared at the Japanese Kanosoke Matsushita, who created it in 1918 for the Japanese market.

Initially, all the sockets were only external – they were placed on the wall, i.e. holes in the wall for them were not cut. The fact is that the insulation of electrical wires 100 years ago was extremely short-lived, the only way to timely replace a wire that was bare in places was to constantly monitor its condition. In addition, the need to enter electrical wiring inside the wall added work to the builders and was too expensive at that time..

Electrical outlet design

The basis of an electrical outlet is an element equipped with contacts for connecting to electrical wiring, terminals for powering the contacts of a plug. The metal support, which is a square plate with a cutout for the socket base, is equipped with side spacers that fix the socket in a cylindrical socket hole cut for it in the wall.

Fastening of contacts: screw – the bare ends of the wires are clamped in the contacts of the socket with screws using a screwdriver; through the quick-clamping unit – the wire is held by the terminals on the springs. It should be noted that both methods of attaching the wiring to the outlet are quite effective..

Outside, the socket is covered with a decorative insulating cover that covers the installation socket on top or covers the socket from above and on the sides – for external installation sockets. Earthed electrical outlets are equipped with an additional ground contact and terminals that make contact with the grounding pins of the plug when connected.

The base of the socket is made of ceramics or special plastics, which contain enhancing additives that increase heat resistance and strength, resistance to fire and ultraviolet radiation, and reduce static. If earlier the body and the base of the wiring elements were made of carbolite (phenolic), today this plastic is not popular – after a few years, products from it lose strength and crumble.

Unlike unsightly Soviet-style sockets, modern wiring products are not only resistant to short circuits and mechanical stress on the case, but also have an attractive design that does not contrast with the overall design of the room..

Types of electrical outlets used in different countries

If you have the impression that electrical sockets of one type are common on Earth, this is not so. Some of them are popular in many countries, but not all over the planet. By the way, the voltage of the electrical household network and the frequency of alternating current in the countries of the American continent differs from that adopted in the countries of Europe and Asia: voltage 100-127 V, frequency 60 Hz – USA, Canada, Mexico, some South American countries, Japan, Saudi Arabia; all other countries of the world – voltage 220-240 V, frequency 50 Hz. Exceptions: Peru, North and South Korea, Philippines – household voltage 220-240 V, frequency 60 Hz; Taiwan and Madagascar – voltage 100-127 V @ 50 Hz.

So, let’s look at the main types of sockets:

Type A (NEMA 1-15), designed for 15 A / 125 V – for a plug with two flat pins, rectangular cross-section without grounding contact. Since 1962, their installation has been banned in the United States and Canada, but they are still found in old buildings. Externally similar power outlets are used in Japan (local standard JIS C 8303, class II), but American-made electrical appliances with similar plugs cannot be powered from such outlets. the voltage and frequency of the current in the household electrical network in Japan is below – 100 V and 50 or 60 Hz, depending on the prefecture;

Type B (NEMA 5-15), designed for 15 A / 125 V. The holes in such sockets are U-shaped – for two flat pins located in parallel, and for a semi-oval ground contact located above them. Externally similar: Japanese JIS C 8303, class I (15 A / 100 V) and American NEMA 5-20 (20 A / 125 V);

Type C (CEE 7/16), designed for 16 A / 250 V. On the territory of the CIS, type C is better known as a euro socket. Designed for a plug with two round, 4 mm contacts, amperage up to 2.5 A and mains voltage up to 250 V. Externally similar: German-French CEE 7/17 (16 A / 250 V) with 4.8 mm holes , the most common in South Korea, as well as the Russian GOST 7396.1-89 C 1 (6 or 16 A / 250 V) with 4.5 mm holes;

Type D (BS 546), rated for 5 or 15 A / 250 V – for a three-prong plug with a diameter of 5.08 mm to 7.06 mm and an earthing pin from 7.06 to 8.71 mm. This type of socket is designed for the former colonies of Great Britain – India (local standard IA16A3) and South Africa (local standard SABS 164);

Type E (CEE 7/5), designed for 5 or 15 A / 250 V, developed in France. An electrical outlet of this type has two holes for contacts with a diameter of 4.8 mm – the grounding pin protrudes from the body of the outlet like a thorn;

Type F (CEE 7/4), designed for 16 A / 250 V – a modern modification of the German Schuko socket, equipped with grounding contacts. The socket is equipped with two grooves, lying in line with the contact holes, the grounding connectors are perpendicular to the contact holes;

Type E / F (CEE 7/7), rated for 16 A / 250 V. This type is a universal plug, suitable for both type E sockets (with a protruding earthing pin) and F sockets (with two earthing plugs);

Type G (BS 1363), rated for 13A / 230-240V, designed in the UK. The socket has three rectangular holes for contacts – two of them are located in parallel, the grounding contact is vertical. The plug has a 13 amp fuse. This type of plug is popular in England and Asia;

Type H (P.32), designed for 16 A / 250 V, used only in Israel. Since 1989, the three flat Y-shaped contacts have been replaced by rounded ones with a diameter of 4.5 mm. Similar sockets are used in Thailand (TIS 166-2549), but their contacts are smaller – 4 mm;

Type I (AS / NZS 3112), rated for 10 A / 240 V. Two flat contacts are located in relation to each other in a V-shape, the ground flat contact is above them. Used in Australia and nearby islands, as well as in Argentina (IRAM 2073). A similar type of sockets is used in China (CPCS-CCC) – its contacts are wider by 1 mm and are located in the opposite direction compared to the Australian type;

Type J (SEV 1011), designed for 10 A / 250 V, developed and used in Switzerland. Three 4mm pins – two on the same line, one just above and between them. This type of plug is diamond-shaped, so the sockets are equipped with a diamond-shaped socket;

Type K (107-2-D1), rated for 13 A / 250 V. Two 4.8 mm contact holes, the grounding hole underneath is truncated by 1/3;

Type L (CEI 23-16 / VII), rated for 10 or 16 A / 250 V. All three pins, including ground, are located on the same line. The diameter of the contacts of the plug for 10 A is 4 mm, for 16 A – 5 mm.

Type M (BS 546), rated for 15 A / 250 V, widespread in South Africa. Outwardly similar to type D, but its larger diameter contacts – 7.5 mm.

Such a variety of types of wiring products creates problems mainly for tourists – it will be impossible to use household appliances taken with them, for example, an electric razor with a plug that does not meet local standards for electrical outlets. And if the use of an adapter adapter helps to solve the problem with the mismatch of the plug connector, then a lower or higher voltage in the household power supply of a given country is a serious obstacle. Therefore, large hotel chains are trying to use only Euro sockets – as the most common on our planet..

Choosing an electrical outlet

First of all, what are the plugs for the household appliances in your home? If the Soviet model, then the euro sockets will not suit them – they are designed for contact pins of a larger diameter – 4.8 mm, while the Soviet ones have a diameter of 4 mm. Although swapping a Soviet-style plug for a Type-C plug is not difficult.

The second and no less important point is what is the current consumed by this household appliance? For most household electrical appliances, an electrical outlet designed for a current of 10 amperes will be sufficient – the maximum permissible current strength for each model of outlet is indicated on its back and in the passport. Exceptions: powerful air conditioner with a current strength of 14 A; microwave oven, whose current strength is 12 A; electric heater developing a current of 11 A; a kitchen electric stove, for which a special power outlet is required, because the current developed by this electrical appliance reaches 46 A – for these household electrical appliances, the sockets must be selected separately.

In the case of powerful electrical appliances, there is one more point – will the wiring withstand the load from them? Standard household wiring is rated for a maximum current of 10 A, i.e. with a greater load, it will simply burn out. The load on the wiring is calculated in total, according to the power of all simultaneously connected electrical appliances. If the total current exceeds 10 A, a complete / partial replacement of the wiring is required, only the sockets will not solve this problem.

You can calculate the current strength for any electrical appliance in this way: divide the power (W) indicated in its passport by the voltage of the household electrical network, equal to 220 V in the CIS.

With or without grounding? Of course, a grounded electrical outlet is much better than a regular one – there is less chance of getting an electric shock. But in most residential buildings in Russia and the CIS, the wiring is made without a ground loop, i.e. the required ground wire is simply not available. And if it is not there – what’s the point in a grounded outlet?

Screw or quick-release contacts? In my opinion, there is not much difference here – except that it is easier to install the ends of the wiring into the quick-release contacts. By the way, if the electrical wiring in the house is made with a flexible, stranded copper wire, then it is better to choose sockets with screw terminals – it will not be easy to insert a flexible wire into quick-release contacts, because it will slide out.

Sockets and switches with LEDs are good in the dark – they are easier to spot in the twilight, which is quite convenient. But they are only suitable for corridors – you should not install such wiring accessories in living rooms, because points of light on them will attract the eye like a magnet and interfere with rest.

In children’s rooms, it will be correct to install electrical outlets with automatic overlapping of contact holes – in the absence of a plug inserted into them, the holes are closed with a plastic curtain, which moves only when both contacts of the plug are inserted. In other words, the child’s attempts to put something inside such an outlet will not be successful, which is good.

There are models of outlets from which it is easy to remove the plug – at the push of a button, which is convenient for household appliances that are periodically used, for example, a microwave oven or a food processor. Most often, such electrical outlets are installed in the kitchen..

The degree of protection against moisture is important for rooms with high humidity and when installed outside the home – in these cases, power outlets with an IP of at least 44 are required. In normal household conditions, IP 22 outlets are sufficient..

The color and design of the socket housing is matched to the overall design of the room where it will be installed. Standard colors are white and “ivory” (white with a cream shade), in the line of large manufacturers the range of colors is much wider, it includes both pastel and bright shades, for example, sapphire. The shape of the case does not have to be the usual round or square – explore the products of famous brands, they have a lot to choose from.

Attention: regardless of the type of outlet chosen, it must be certified, as evidenced by a paper copy of the certificate – unfounded claims of sellers that there is a certificate, do not take on faith!

Self-installation of electrical outlets

I’ll start with the procedure for installing an internal or hidden type socket. We turn off the power supply to the apartment by turning the handle of the package switch in the switchboard – a mandatory operation carried out before the start of electrical work!

It is necessary to remove the outer cover by unscrewing the screw that secures it to the ceramic or plastic base and set the cover aside by inserting the screw into it. After making sure that the electricity is really turned off, you should remove the cover from the dismantled outlet. Loosen the spacer screws and partially remove the old electrical outlet from the wall socket, leaving it hanging from the wires. Then disconnect the wires from the contacts, remembering the order of their connection (if you are not sure – take a photo!).

If the new socket has screw contacts, loosen them with a few turns of the screwdriver, then insert the bare ends of the wiring into the corresponding clips. After tightening the contact screws or inserting the ends of the wiring into the quick-release contacts, you need to bring the base of the socket into the hole intended for it in the wall, align the position – make sure that the metal support does not protrude beyond the edges of the hole, otherwise there will be no tight fit of the socket cover to the wall plane.

Tighten the spacer screws alternately: right half, then left half, after each to the limit, make sure that the base of the socket is securely fixed in the hole in the wall. Next, a plastic cover is installed, screwed in with a screw – the socket is installed. To be sure that it is firmly installed, lightly shake the cover with your fingers. Check if there is power in the outlet – for this you need to turn on the power supply and insert a special test screwdriver or a plug from a table lamp into a new outlet. If there is no power, turn off the general power supply, remove the cover from the outlet, loosen the side braces and check if the wires are correctly connected to the connectors of the contacts and if they are connected at all.

Possible installation problems: the existing protrusions in the wall outlet are worn out and reliable fixation of the electrical outlet fails; there were no protrusions initially.

In the first case, an invoice repair kit will help – it consists of two half rings made of hard plastic, connected to each other. The diameter of the ring formed by them coincides with the diameter of the standard hole for the socket (Soviet standard – 80 mm). Theoretically, the plastic rings should be inserted into the hole for the outlet in the assembled state, but it may not fit – the joints of the half-rings between themselves often protrude beyond the required diameter. Cut the fasteners with a knife on both half rings, then place them inside the socket hole under the spacers of the outlet and, holding them with the fingers of one hand, wind the base of the electrical outlet and tighten the screws of the spacers.

If there are no fastening protrusions, a cylindrical plastic box is inserted into the socket hole, on the walls of which there are mounting protrusions for fastening the socket. There is a hole in the bottom of the box for wiring outlets – try on the box in the socket hole, make sure its edges do not protrude out of the hole. Then plug in the power outlet as described above..

An outdoor outlet or, as they say, an overhead outlet is installed, by and large, on any surface – if it is placed outside the building, then only on a vertical plane. Unscrew the screw holding the outer cover, remove it to the side. The bare ends of the wiring are inserted into the contacts of the base of the external socket and fixed. At the base of the external socket there are holes for fastening – if the mounting surface is wooden, self-tapping screws for wood are inserted there, if concrete or brick – self-tapping screws for concrete. The self-tapping screws are tightened, an external cover is attached to the top of the socket. This completes the installation. An important point: for outdoor sockets mounted outside the building, it is better to use double-braided wiring, and its outer (top) layer should be thick enough.