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Double Schuko socket with one plug inserted. The dot in the middle of the socket is a screw head, not a third hole. Illustration of the originally two Schuko plug and socket designs from the patent specification of patent DE granted on 22 December . The right-hand column shows the design that prevailed and is in use today.
Schuko ( ) is a plug/socket system used in much (but not all) of Europe. It is a registered trademark[1] referring to a system of AC power plugs and sockets that is defined as "CEE 7/3" (sockets) and "CEE 7/4" (plugs). A Schuko plug features two round pins of 4.8 mm diameter (19 mm long, centres 19 mm apart) for the line and neutral contacts, plus two flat contact areas on the top and bottom side of the plug for protective earth (ground). The socket (which is often, in error, also referred to as CEE 7/4) has a predominantly circular recess which is 17.5 mm deep with two symmetrical round apertures and two earthing clips on the sides of the socket positioned to ensure that the earth is always engaged before live pin contact is made. Schuko plugs and sockets are symmetric AC connectors. They can be mated in two ways, therefore line can be connected to either pin of the appliance plug. As with most types of European sockets, Schuko sockets can accept Europlugs. Schuko plugs are considered a very safe design when used with Schuko sockets, but they can also mate with other sockets to give an unsafe result.
Schuko is a shortening of the German term Schutzkontakt (literally: protective contact),[1] which indicates that plug and socket are equipped with protective-earth contacts (in the form of clips rather than pins). Schuko connectors are normally used on circuits with 230 V, 50 Hz, for currents up to 16 A, although e.g. South Korea uses them at 60 Hz for historical reasons.
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The Schuko system originated in Germany. It is believed to date from and is attributed to Albert Büttner, a Bavarian manufacturer of electrical accessories.[2] Büttner's company, Bayerische Elektrozubehör AG, was granted patent DE 489 003 in for a Stecker mit Erdungseinrichtung ('plug with earthing device').[3] Büttner's patent DE 370 538[4] is often quoted as referring to Schuko, but it actually refers to a method of holding together all of the parts of a plug or socket with a single screw which also provides clamping for the wires; there is no mention of an earth connection in DE . At this time Germany used a 220 V centre tap giving 127 V from current pins to earth,[citation needed] which meant that fuse links were required in both sides of the appliance and double pole switches. Variations of the original Schuko plug are used today in more than 40 countries, including most of Continental Europe.
France, Belgium, Czechia, Slovakia and Poland use the CEE 7/6 plug and CEE 7/5 socket with the same size and spacing of the main pins but with a male protective-earth pin on the socket instead of the earth clips, and without the guiding notches at the sides. Most modern moulded Schuko plugs, and good-quality rewirable replacements, are a hybrid version ("CEE 7/7") with an aperture that accommodates the earth pin of CEE 7/5 sockets. CEE 7/6 plugs that need to be polarised are configured in such a way as to only be inserted correctly in earthed sockets, however the old CEE 7/1 2-pin unearthed socket is inherently dangerous with equipment that should be polarised, for example table lamps with an Edison screw lamp but only a single pole inline cord switch in lieu of a double pole switch. The safety of polarisation was not helped by several years of confusion when the correct connection of sockets was transposed.
Early in the 21st century, CEE 7/7 [clarification needed] became the de facto plug standard in many European countries, and in some other countries that follow CENELEC standards. European countries that do not use CEE 7/7 are:
In Italy, CEI 23-50 is the dominant standard and it also includes Schuko sockets (P 30 = CEE 7/3) and plugs (S 30 = CEE 7/4, S 31 = CEE 7/7, S 32 = CEE 7/17). Appliances are commonly sold with Schuko-type plugs (as well as Europlugs), while Italian-type plugs have become rare today and almost only power strips, cable reels and adaptors are sold with them. Some sockets (P 30 and P 40) accept both types, the remainder accepting one or the other. Schuko sockets are most commonly used for larger-rated appliances such as washing machines, and are particularly common in South Tyrol, with its cultural, economic and tourist connections with Austria.
Although Schuko has never been a standard (or the de facto norm) in Belgium or France, it is sometimes encountered in older installations in eastern regions of Belgium and Alsace.
In Ireland, Schuko was commonly installed until the s.[5][6][7] For safety reasons and to harmonize with the UK and thereby avoid having a different outlet type in Northern Ireland and the Republic of Ireland, the Republic standardized on BS (transposed into Irish Standards as IS 401 (Plug) and IS 411 (Socket outlet). Schuko has been phased out of use in Ireland and will be rarely encountered. Some hotels provide a Schuko outlet alongside BS outlets for the convenience of visitors from the Continent.
Russia, while maintaining its own mains connector standard, has it largely harmonised with the relevant European regulations since Soviet times. The original Soviet standard was mostly compatible with Europlug (the traditional Soviet plug used straight 4 mm pins with 19 mm spacing and thus Soviet sockets were able to easily accept europlugs), and has been modified to accept 4.8 mm pins, due to the large volume of imported appliances equipped with the Schuko plug. Nowadays most sold and installed sockets in Russia are Schuko ones, though they may lack a connection to earth, especially in older buildings, as this wasn't required by the Soviet wiring regulations.
Denmark gave full permission to install Schuko wall sockets in , and such sockets can be found for sale at some Danish constructionware stores,[8] but the Danish Type K remains the most common earthed socket type in Denmark by far.
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CEE 7/4 Schuko plug and CEE 7/3 Schuko socket
Schuko outlets manufactured by Busch-Jaeger Elektro . The right socket has protective shutters (gray in color) and the left does not.
When inserted into the socket, the Schuko plug covers the socket cavity (1), thereby preventing users from touching connected pins. It also establishes protective-earth connection through the earth clips (2) before the line and neutral pins (3) establish contact. A pair of non-conductive guiding notches (4) on the left and right side provides extra stability, enabling the safe use of large and heavy plugs (e.g. with built-in transformers or timers).
Some countries, including Portugal, Finland, Denmark,[9] Norway and Sweden, require child-proof socket shutters; the German DIN -1:-01 standard does not have this requirement.
Compatibility with other plug/socket types[
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Non-earthed CEE 7/1 socket (bearing Dutch standard approval) that accepts Schuko plugs
Schuko plug partially inserted in CEE 7/1 non-earthed socket, pins are in contact but exposed. There is no connection for the earthing contact.
Schuko sockets can accept two-pin unearthed Europlug (CEE 7/16) and CEE 7/17. Less safely, Schuko plugs can be inserted into many two-pin unearthed CEE 7/1 sockets and into some sockets with a different form of earth connection that will not mate with the earth contacts on the Schuko plug (e.g., some variants of the Danish socket). Many such sockets also lack the cavity required to prevent users from touching the pins whilst inserting the plug.
CEE 7/7 plug, compatible with both CEE 7/3 (Schuko) and CEE 7/5 socketsThe CEE 7/7 plug is a hybrid which includes both side earthing strips, as in CEE 7/4 Schuko, and an earthing aperture, as in the CEE 7/6 plug. It can therefore achieve an earth contact with both CEE 7/3 (Schuko) and CEE 7/5 sockets.
In Italy, Chile, Peru and Uruguay, hybrid versions of Schuko sockets (called P 30) are seen with an extra hole that will take the smaller variant of Italian CEI 23-50 plugs. There are also hybrid Schuko sockets (called P 40) with three extra holes and a wider cavity that will also accept the larger variant of Italian plugs.
Schuko sockets are unpolarised; there is no way of differentiating between the two live contacts (line which is approximately 230 V to earth and neutral which is approximately 0 V to earth) unless the voltage to earth is measured prior to use.
Although Schuko is incompatible and the pin spacing should not allow it, as the Schuko pins are slightly closer together, it is possible to dangerously force many Schuko round pin plugs (where the plastic is compliant enough) into many UK BS rectangular pin sockets, using a match or other probe to push into the earth shutter release. Due to the minimal contact area that must transmit high current, there is risk of overheating and thus fire. Where earthing is required, no earth contact will be made as Schuko plugs use side contacts for earthing rather than a third pin, and BS sockets have shutters that require the longer earth pin to be entered to open the line and neutral shutters, which prevent Europlugs and Schuko plugs from being inserted.
The IEC -1 standard was intended to address some of the issues regarding polarisation and replace Schuko, but the only countries that have adopted it are South Africa and Brazil.
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Sockets allow the connection between the utilities and the electrical system and are crucial for devices and appliances correct functioning, no matter where they are placed.There is a wide range of sockets that adapt to the standards of the country of reference: the sockets in Italy are regulated by the CEI 23-50 standard that sets the technical features of the various types of plugs and sockets and any related tables aimed at standardization. Read our in-depth analysis and discover all the different types of sockets available in Italy and abroad, their features, how to recognize them and other information!
Sockets allow the connection between the utilities and the electrical system and are crucial for devices and appliances correct functioning, no matter where they are placed.
It is the end of a system and allows the access to the energy through a specific cables system.
There is a wide range of sockets that adapt to the standards of the country of reference: the sockets in Italy are regulated by the CEI 23-50 standard that sets the technical features of the various types of plugs and sockets and any related tables aimed at standardization.
Read our in-depth analysis and discover all the different types of sockets available in Italy and abroad, their features, how to recognize them and other information!
All sockets have different features depending on their type and country of origin: Italian, Swiss, American, German and other models and all corresponding adapters.
They are constantly powered and feature holes (intended to house the plugs of the devices they will supply) to which the corresponding cables are connected.
Each country has its own standards that determine differences in current load (expressed in Ampere and corresponding to a power in Watt), shape, number of contacts and size.
Read our guide and discover all different sockets.
In North and Central America and in the Japanese archipelago you find two types of 120 Volt sockets:
They are very similar to those used in the UK, with thinner blades and can be used with universal adaptors.
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In Italy the type C socket is ordinary, powered by 1.5 mm section cables and with 2 or 3 4 mm diameter symmetrical holes. It can deliver current of up to 10 A with a maximum power of W. It is recommended not to connect energy-intensive appliances via a Schuko adapter or triple plug, thus avoiding possible overheating. The second Italian model is the L socket one, more performing than the Type C.
It is homologated for 16 amps and supports power up to 3.5kW, has larger diameter holes and is compatible with 2.5mm lead wire. You can use it for powerful appliances such as electric ovens and dishwashers.
The Schuko socket, also known as F socket, is easily recognizable through the two horizontal holes and can deliver up to 16 Ampere. In this case, the grounding hole is replaced by two lateral contacts. It is ideal for powering large household appliances, PCs, monitors and other energy-intensive devices.
It is used in Germany, Austria, the Netherlands, Spain, Sweden, Norway, Finland, Portugal, and Eastern Europe, and has now become (with the E-type socket) the European standard.
The English socket is used in the UK, the Commonwealth and former British colonies, including Hong Kong and India. It supplies 240V and features three holes arranged in a triangle: two horizontal rectangular ones and a vertical one for earthing system. It has a fuse that can be 3, 5 or 13 Ampere and protects the connected device.
The French socket is analogous to the Schuko and is Europe's second most heavily used. It features two holes, and the fundamental difference is that a male connector acts as an earthing system.
The Swiss socket has features similar to the Italian L model: it has three holes arranged in a triangle and can adapt well to Italian-type C bipolar plugs.
The Chinese and Australian socket is used also in Argentina: it has rectangular holes and two poles of the current to create a V. It supplies from 10 to 20 Ampere.
H sockets feature large holes in the centre to house the round pin version of the Type C plug. The Type H plug can be very dangerous as it lacks insulation to protect against electric shock.
It is currently being replaced in favour of a model with round pins.
In Denmark, in addition to models C, E, and F, the K socket is also used: similar to the German F socket, it features three poles, but the difference lies in the use of a third pin for the earthing system instead of the two tabs of the Schuko. The Government bodies have approved the use of the Schuko socket in Denmark, and therefore, the K model will progressively disappear.
Type D socket features three large round prongs arranged in a triangle with a nominal output of 5 Amps.
M-type plugs are used in conjunction with Type D sockets for larger appliances. That's why some plugs work with both Types D and M.
The European UNEL socket has two cylindrical contacts of 4.8 mm in diameter for the phase and neutral contacts and supports both German and Italian 3-pole plugs (including an earthing system). It can connect loads up to 16Amps in 220V alternating current circuits. The combination of UNEL plugs and sockets is very safe.
It is used in the same countries as socket A and C and is also known as Europlug: it is the Italian socket with two poles, without earth pin. It is used in many European countries and is the most widespread internationally.
Schuko socket, also known as CEE7/4, is currently used in most European countries because live parts are well protected and can connect household appliances, gardening tools and electric vehicle charging.
This socket ensures total safety: its structure makes accidental contact between the hand and the pins of the socket impossible.
It has progressively become the standard European socket as it represents the solution adopted by manufacturers for a wide range of small and large household appliances currently on the market.
The CEI 64-8 standard lays the application standard of this type of socket in kitchens and washing machines connection to completely eliminate the use of adapters.
Refrigerators, washing machines, ovens, dryers, dishwashers, appliances that absorb a lot of energy are usually powered by a Franco-German socket, which allows their use in all countries of the European Union.
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There are currently 15 different types of sockets available to which, as we have saw earlier, different letters are associated.
Schuko or C sockets are mainly used in Italy and in most European countries.
The most widespread in the world (where the mains power supply is generally between 220 and 240 volts) are the A and C models.