European mains power

This post is about European mains power. Electricity in EU countries conforms to the European standard, coming out of the wall socket at 230 volts alternating at 50 cycles per second. While the voltage and frequency are fixed, the mains connectors and wiring practices can vary between different countries in Europe.

One thing to note on European power outlets is this: In most European countries mains outlets are not polarized, and you can put the plug in both ways, so you almost never know which wire is live and which is neutral. Typically, Europeans do not maintain consistent identification of line and neutral throughout their power system as is the practice in North America. Consistent with this practice, the Continental European plug can be rotated to either of two positions and plugged into the socket. Thus, the common electrical system in Europe is unpolarized (i.e., line and neutral are connected at random). In fact, most plug types used in Europe are not polarized. The ungrounded plugs have been non polarized, grounded outlets are either polarized or non polarized depending on country.

History of European 230V power

Europe’s power grid, the world’s most interconnected, is set at 230 volts (an EU standard since 2008). Before that the voltage standard had been 220V (most countries) or 240V (UK and Ireland).

It was the Germans who introduced 220V AC power in Europe over 100 years ago. It was around 1893 when the AC frequencies were standardized at 60Hz (US) and 50Hz (Europe). At that time there were some systems that used 120V and also 220V systems. Europe had developed its 220-volt (now 230-volt) system after learning from the American experience, and before any massive infrastructure changes would be required. Cost was the main reason Europe went with 220 volts (now 230): higher voltages allow the use of thinner wire, meaning less copper in the early days of power lines. Power companies could save money on wire by using 220 volts rather than 110. This became the model for electrical distribution in Germany and the rest of Europe and the 220-volt system (later 230-volt) soon became the European norm.

Single phase power in Europe The nominal European voltage is now 230V 50 Hz (formerly 240V in UK, 220V in the rest of Europe). European mains voltage is presently specified as being 230 V+10%/−6% (253-217V) specification will broaden to 230 V±10%, requiring electrical goods to operate correctly on a supply anywhere between 207 and 253 V. The “harmonised voltage limits” in Europe are now: 230V -10% +6% (i.e. 207.0 – 243.8V) in most of Europe (the former 220V nominal countries) 230V -6% +10% (i.e. 216.2 – 253.0V) in UK (former 240V nominal) his is really a fudge and means there is no real change of supply voltage, only a change in the “label”, with no incentive for electricity supply companies to actually change the supply voltage. To cope with both sets of limits an equipment will therefore need to cover 230V +/-10% i.e. 207-253V.

Outlet wiring

Modern European 230V (50Hz) supply feeding the mains outlet consists of 3 wires that are typically: hot, neutral, and safety ground. The 230V (50Hz) is obtained between the hot and neutral lead. The current available from the outlet depends on the maximum current rating of the breaker in mains panel that is normally 10A or 16A (in UK there are maximum 13A fuse inside mains plug). Older building can have older outlets that do not offer grounding on “safe” locations (normal rooms) and grounded outlets on “dangerous” locations (like outdoors, washing room, kitchen).

There modern colors used in house wiring in Europe are based on IEC standard: GREEN with YELLOW stripes is Ground, BLUE is Neutral, and BROWN is Live. The typical wire thickness (for live, neutral and ground) is either 1.5 mm2 (for 10A circuits) and 2.5 mm2 (for 16A circuits). The extension cords typically are built using 1.5 mm2 cable. The cables feeding equipment are typically use 1.5 mm2, 1 mm2 or 0.75 mm2 wires depending on the power equipment uses.

There is not usually hard guarantees which hole on the outlet is neutral and with is live. The hot and neutral wires are interchangeable as far as the equipment is concerned (be warned that there are some exceptions in some countries). Both are power carrying wires. In many parts of Europe (nordic counties, Germany etc), the normal 3-wire receptacle is symmetrical so that the neutral and hot wire connections can be swapped by simply rotating the plug.

There is not even guarantees that one of the side is neutral, because it is possible that in some locations both the mains outlet power carrying contacts can be “live” with 230V between them. On some countries (for example some locations in Norway and some old installations on some other countries) both current carrying wires on outlet can be “live”. In hospitals the mains outlet designed to be used for medical equipment could be powered from safety isolation transformer, so neither side is “neutral”.

In most parts of Europe the mains wiring is is wired as radial system, which means that there is a straight wire that comes from the mains panel to the fixed load or mains outlet. There can be one or more than one outlet connected to the same wire. That wiring is protected with with a breaker or fuse (typically rated for 10A or 16A depending on how much current is needed and how thick wires are installed). In modern installations there is normally a 10A or 16A breaker on the mains panel that disconnects the live wire when there is short circuit or overload and neutral side is not protects. In addition in modern installations there is usually also a ground fault protector that protects one outlet or a group of outlets. In locations where both sides of mains outlet are live, two pole breakers are used (disconnect both wires going to outlet if there is overload or short circuit). UK is a special case because there residential installations use Ring circuit wiring where the mains plugs have a built-in fuse.

Mains plugs

The standard, Class I grounded mains, plugs used in Germany, Austria, the Netherlands, Sweden, Norway, Finland, and Russia are the CEE 7/4 and CEE 7/7 plugs. Because this standard is used so commonly throughout Europe, we refer to it as the “Continental European” standard. Both styles have two 4.8mm round contacts on 19mm centers. s the “Continental European” standard. Both styles have two 4.8mm round contacts on 19mm centers. Grounding is achieved through the grounding clips on the sides of the plug body.

The CEE 7/7 plug also has a female receptacle, which permits it to be plugged into the French/Belgian sockets that have a male grounding pin.


German (type F, CEE 7/3 socket, CEE 7/4 plug, Schuko) is the most common mains power socket in Europe. The most common socket in Europe is the Schuko (Schutzkontakt is German for ‘Protective contact’). The plug has two pins, and along with the socket can be identified by the two metal earth contacts on each side. Schuko is a standard used primarily in Germany and Austria, Finland, Sweden, Norway and several other countries.

The SCHUKO is rated at 230v 16A, and has two 4.8mm x 19mm pins. The metal contacts at top and bottom of the outlet are the “Schutzkontakte”, i.e. earth. Because the plug is symmetrical, there is no way to know which line is hot and which is neutral for a device. Only earth is always the same.


A typical SCHUKO outlet has three electrical connections, which are the “hot”, “neutral”, and “grounding” wires. The hot and neutral wires are interchangeable as far as the equipment is concerned. The normal SCHUKO 3-wire receptacle is symmetrical so that the neutral and hot wire connections can be swapped by simply rotating the plug. SCHUKO plug can be connected either way around, and there is no strong convention as to whether sockets have the live wired to the left or right side of the receptacle.

The Schuko system originated in Germany. It is believed to date from 1925 and is attributed to Albert Büttner, a Bavarian manufacturer of electrical accessories At this time Germany used a 220 V centre tap giving 127 V from current pins to earth, 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.

Why it is not important where we connect our hot and neutral wire when connecting them to our Schuko plug? Is it because current flows in both directions and equipment are designed to cope it. This inherently stupid sounding power plug design from 1925 that is safe enough when certain limitations are met. While obviously not ideal, this symmetry is not a big problem so long as all appliances are built in such a way as to be still safe when the two main wires are swapped. As almost everything is being produced for a global market today, in practice this is always the case – or at least manufacturers always claim and usually provide it. It is UTTERLY ESSENTIAL that anything it is used with may be safely used with phase and neutral in either of the two possible arrangements.

The SCHUKO connector is pretty safe design. Overall though, there aren’t millions of people being electrocuted by Schuko. In fact, it’s generally one of the lowest risks out there because the plug is pretty well designed to be be safe. SCHUKO plug used in some of the most conservative and safety conscious regulatory environments, such as the Nordic region. So, it’s hardly a major risk or concern.

When you insert SCHUKO plug into the socket, the earth connector makes contact first and then the live prongs. By the time an electrical connection is made, there is almost no gap left between the socket and the plug, no room for an inquisitive toddler to put his fingers or other conductive objects. There are also safety shuttered outlets, where the shutters on SCHUKO sockets have to be pressed simultaneously in order to push them aside. Pushing only one will not make it slide away.

Schuko plugs are required for devices with metal cases, the case needs to be connected to earth ground in several places, so any electrical fault would connect line to earth or neutral to earth. SCHUKO sockets also accept non-grounded EURO plugs that are used on “dual insulated” equipment that are designed to be safe to be operated without ground.

SCHUKO design is very safe for users to use. When inserted into the socket, the Schuko plug covers the socket cavity (1) and establishes protective-earth connection through the earth clips (2) before the line and neutral pins (3) establish contact, thereby preventing users from touching connected pins. 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, Norway and Sweden, require child-proof socket shutters; the German DIN 49440-1:2006-01 standard does not have this requirement.


The second most common socket is the French type, which like the Schuko is rated at 230v 16A, and has two 4.8mm x 19mm pins. France, Belgium, the Czech Republic, Slovakia and Poland use the CEE 7/6 plug and CEE 7/5 socket with the same size and spacing of the main pins as SCHUKO but with a male protective-earth pin on the socket instead of the earth clips, and without the guiding notches at the sides. The earth connection is made by an earth pin which protrudes from the socket, and engages with a hole in the plug.

The protruding earth pin means that the plug can only be inserted one way around, but the major issue is that until 2002, there was no convention as to whether sockets had the live wired to the left or right receptacle You therefore have a 50:50 chance of it being wired “the correct way” and unlike with the Schuko socket, you cannot rotate the plug 180 degrees.

In order to bridge the differences between German and French standards, the CEE 7/7 plug was developed. It has a hole to accept the earth pin on a French socket, and side strips to connect to the earth clips on the side of German sockets. 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.

Other outlet types

Denmark and Greenland use their own 16A socket. The socket looks quite similar to a Schuko/French socket, but the grounding is different than in those (third pin on socket). Denmark also supports using French sockets and Schuko sockets.

Historically Italy has had its own specific three pin plug and socket, available in 10A and 16A versions. Many modern sockets will accept both 10A and 16A plugs. Many buildings now have the Bipasso/Schuko socket, which can be used with both Italian and Schuko plugs. Also Switzerland and Liechtenstein use their own specific three socket, available in 10A and 16A versions. Britain has it’s own set of mains outlets that are different from ones used in continental Europe.


The Europlug is a flat, two-pole, round-pin domestic AC power plug, rated for voltages up to 250 V and currents up to 2.5 A. It is a compromise design intended to connect low-power Class II appliances safely to the many different forms of round-pin domestic power socket used across Europe. It is compatible with SCHUKO, France type outlet and several other outlet types in use in Europe (except UK outlets).

The Europlug design, intended for use with socket-outlets meeting other standards, appeared first in 1963 as Alternative II of Standard Sheet XVI in the second edition of CEE Publication 7 by the contributing members. The Europlug is therefore sometimes also referred to as the “CEE 7/16 Alternative II plug” or simply as the “CEE 7/16 plug”.

It is a small size plug that allows compact power cables and mobile phone changers. Europlugs are only designed for low-power (less than 2.5 A) Class II (double-insulated) devices that operate at normal room temperature and do not require a protective-earth connection. The Europlug is designed to be compatible with mains socket types C, E, F, and K (all have 4.8 mm holes with centres spaced 19 mm apart).The Europlug is not designed to be compatible with mains sockets used in UK.

The dimensions of the Europlug were chosen for compatibility and safe use, such that with continental European domestic power sockets. The plug is designed so that a reliable contact is established when the plug is fully inserted and no live conductive parts are accessible while the plug is inserted into each type of socket: it is not possible to establish a connection between one pin and a live socket contact while the other pin is accessible.

The pins of the Europlug are 19 mm long. They consist of a 9 mm long conductive tip of 4 mm diameter with a rounded ending, followed by a 10 mm long flexible insulated shaft of not more than 3.8 mm diameter. The two pins are not exactly parallel and converge slightly; their centres are 17.5 mm apart at the tip and 18.6 mm apart at the base. The elasticity of the converging pins provides sufficient contact force for the Europlug’s current rating with a variety of socket-hole arrangements.

Europlugs are designed to be non-rewirable and must be supplied attached to a power cord. Europlugs are designed to be used with ‘double-insulated’ or ‘all-insulated’ apparatus is made which does not require earthing. Double insulation means what its name says, and all live conductors are separated from the outside world by two separate and distinctive layers of insulation. Each layer of insulation would adequately insulate the conductor on its own, but together they virtually negate the probability of danger arising from insulation failure. Typically the double insulated devices are built into insulating plastic case, but in some case also metal case is possible (for example on amplifiers, CD/DVD players and VCRs). Double insulation avoids the requirement for any external metalwork of the equipment to be protected by an earth conductor.

Three phase power

In northern and central Europe, residential electrical supply is commonly supplied with 400 V three-phase electric power, which gives 400V between phases and 230 V between any single phase and neutral. This three phase power system is called THREE-PHASE STAR; FOUR-WIRE; EARTHED NEUTRAL system. Electric power distribution throughout Finland and many parts of Europe is made by 230/400Vac, 3 phase, four wire, Multiple Earth Neutral (MEN). Typically one or three phases are brought into the customer’s premises depending on the maximum demand. Three phase power is normally available in at least Finland, Sweden and Germany being used for ovens, electric stoves, large motors and dryers. Three phase power is also typically available in places where large sound and light systems are used (around stages etc.) and in construction sites. Three phase outlets typically use industrial CEE FORM connectors for three phase temporary power output (typically 3x16A or 3x32A).

When three phase power is used (for example in industrial applications, construction sites and concert AV systems) the most common connector type is five pin CEEFORM connector.

Safety issues on lamps sockets

Edison screw (ES) is a standard lightbulb socket for electric light bulbs. It was developed by Thomas Edison, patented in 1881. Edison screw has been the most commonly used light bulb socket for general lighting for very long time. In Europe the most commonly used Edison light bulb socket sizes are E27 (ES) and E14 (Small ES, SES) with right-hand threads.

For bulbs powered by AC current, the thread is generally connected to neutral and the contact on the bottom tip of the base is connected to the “live” phase. This works for fixed installed lights, but for lamps that are plugged in to the mains outlets, you don’t know which wire going to socket will be live or neutral. Or this reason a “safer Edison” light bulb socket has been developed and is commonly used. That socket has contacts on the bottom and not connected to scree threads (that can be made of metal or plastic). Having the contacts on the bottom of the socket makes the light socket safer to handle when changing the light bulb.


The bulb starts to makes contact with live and neutral contacts on the socket bottom only when it is screwed pretty much full into the socket. The bulb is screwed in at the time so much that the user can’t anymore tough the metal threads of the light bulb.

Wire size and fuses

In continental Europe the breakers/fuse sizes used in the breaker panel are normally 10A or 16A. The wire size inside the wall is normally 1.5 mm2 for outlets protected with 10A fuse/breaker. When the circuit used 16A fuse/breaker, thicket 2.5mm2 wire is normally used to them. The grounded outlets have three wires going to them: live, neutral and ground.

The extension cords are typically built using 1.5 mm2 flexible wire, because it can handle current up to 16A without heating too much (will get somewhat warm on full 16A). Long extension cords for heavy use sometimes use 2.5 mm2 wire thickness.

The cables feeding equipment are typically use 1.5 mm2, 1 mm2 or 0.75 mm2 wires depending on the power equipment uses. The 1.5 mm2 wire is OK for full continuous 16A current, while 1.0 mm2 can handle 10A. The thin 0.75 mm2 wire can handle only 6A current. Those thinner wires are allowed and even safe even on circuit protected with 16A breaker/fuse on the conditions that the equipment being powered is protected so that it can’t take more power than the wire can handle (fuse inside rated to power it takes for example) and the mains cable when faces short circuit will trips the up to 16A fuse/breaker before the cable starts to melt.

Equipment design

All devices should be designed to expect live on both mains power carrying wires, because configurations where either one of them can be live or neutral are possible. Under the European Low Voltage Directive (which applies across the whole EU, the EEA and countries that follow CENELEC standards) all appliances brought to market have to be safe to use in either polarity.

The neutral side might not be near the ground potential. It’s also possible that you may have a neutral fault on a TN-C/TN-C-S system as used in the UK and Ireland etc, which could introduce a significant voltage on neutral. There are also installations where both mains wires can be live compared to ground (some locations in Norway, some old installations, some isolated power on hospitals).

Many appliances require an earth connection to operate safely. An earth connection ensures that if there is a fault and an external metal part becomes live, the earth wire safely conducts the electricity away, tripping the circuit breaker or blowing the fuse.

Some appliances do not require an earth connection. They are known as type 2 and will have a symbol of a square inside a slightly larger square on the appliance label. Other clues (although not 100% reliable), are a plastic case or flat 2 core cable. Those dual isolated devices appliances are typically supplied with Euro plug.

For best electrical design safety it would be best that the mains switch switches both mains power wires to guarantee that there is no voltage present in the device when the power is turned off. If a double pole switch is fit for its purpose, voltage and current ratings not exceeded, it will usually be safer than a single pole switch. There is no problem if extension cord has “switched” hot and neutral.

In practical equipment there are many devices that do not switch both lines on mains switch. his indeed means that the power supply electronics is on ground or live potential, when switched off. But I don’t see a big problem here is the device is well built. Some issue pertains to the isolation of devices from live using single pole switches, internal fuses and breaker/cut-outs.

In some cases equipment can have dual fuses (one for each incoming mains wire) to make sure that there is always fuse on the live side. The lack of polarisation might explain why some regulatory regimes in Europe are keen on double pole breakers. Majority of equipment have only one fuse in the mains input, so depending the power plug direction, it might end to be at the live or neutral side. Once single phase 230v is supplied, the lack of polarisations means that on an appliance with a single pole switch, or a device containing an internal fuse/cut-out that there is a 50:50 chance that some parts of the circuitry will still be “live” if it’s turned off or the internal fuse blows or a cut-out trips. Be careful out there!


  1. Tomi Engdahl says:

    UK law requires a suitable fuse to be fitted in each plug to protect the appliance flexible cord.

    Other European countries do not have such requirement.

  2. Tomi Engdahl says:

    So what’s wrong with adapters?

    Nothing wrong with well made adapters (from Europe to US plugs for example) that are used with devices that can handle European 230V mains power.

    This type of adapter will work OK in continental Europe. It is somewhat less safe than real European power cord because of the issues on US power plug (which I feel you can too easily touch live metal parts compared to this Schuko plug). It is as dangerous to use as US outlets just with double voltage (230V) compared to regular US outlet (110-120V). If you touch live parts, you ca get more violent shock. The US wire has normally insulation sufficient to work at 230V as well safely enough, and the protective fuse/breaker in continental Europe (10A or 16A) is of same range as US (15A or 20A). There are also some badly built adapters that can’t handle the full load before melting..

    In UK this kind of connector adapter should have built-in fuse to be safe to use because the breakers on panel are typically much higher value (30 or 32A) and the plugs need to have fuse (3-13A typically) in them to avoid disasters.

  3. Tomi Engdahl says:

    Suomessa käytetään nykyään yleisimmin ns. sukopistorasiaa (lyhenne sanasta suojakosketin), jossa on kaksi holkkia eli ”reikää” pistotulpan kosketintapeille ja sivuilla kaksi kosketinliuskaa pistotulpan suojakoskettimille. Jännitteiset osat eli vaihe ja nolla ovat holkeissa siten, että niihin ei pääse koskettamaan. Nykyaikaisissa pistorasioissa on lisäksi sulkulaitteet, jotka avautuvat, kun niitä molempia painetaan samanaikaisesti pistotulpalla. Jos vaikkapa lapsi yrittää työntää naulaa toiseen pistorasian rei’istä, sulkulaitteet pysyvät kiinni.

    Yhteenveto pistotulppien ja pistorasioiden sopivuudesta on kuvassa alla. Pääperiaate on, että vaarallinen yhteensopivuus on estetty.

    Suomessa on aikaisemmin – 1990 luvun puoliväliin saakka – asennuttu kuiviin, eristävällä lattialla varustettuihin tiloihin pistorasioita, joissa on vain kaksi reikää vaihe- ja nollajohtimille. Siihen aikaan oli myös käytössä luokan 0 (nolla) laitteita, joissa oli pyöreä pistotulppa joka sopi vain tällaiseen pistorasiaan. Tähän vanhaan pistorasiaan voidaan kytkeä kaiken tyyppiset pistotulpat. Tällaisessa asennuksessa ei ole käytössä vikasuojausta, eikä sen suojaustasoa pidetä enää riittävänä.

    Luokan II laitteissa voidaan käyttää pistotulppaa, jossa ei ole suojakosketinta, koska laitteet eivät tarvitse suojamaadoitusta. Ne voidaan kuitenkin kytkeä myös sukopistorasiaan.

    Kuluttajan asennettaviksi tarkoitettuja valaisimia varten asunnoissa voi olla valaisinpistorasiat. Suomessa nykyään käytettävät valaisinpistorasiat ja -pistotulpat ovat pohjoismaista rakennetta.

    Uudisasennuksissa käytetään vain kuvan mukaista luokan I pistorasiaa, jossa on suojamaadoitusta varten ulkoneva tappi. Vanhoissa asennuksissa esiintyy myös yksittäisiä luokan 0 pistorasioita tai ns. kruunupistorasioita, joissa on kaksi erikseen ohjattavaa vaihejohdinta ja yhteinen nollajohdin. Vanha, luokan 0 pistotulpalla varustettu valaisin voidaan liittää vain näihin.

    Teollisuudessa, rakennustyömailla ja vastaavissa tiloissa tarvitaan myös suurempia kolmivaiheisia pistorasioita eli ns. voimapistorasioita. Ne ovat rakenteeltaan pyöreitä ja niissä on viisi reikää (kolme vaihetta, nolla ja suojamaadoitus). Voimapistorasiaan sopivassa pistotulpassa on viisi piikkiä, joista suojamaadoittamiseen tarkoitettu piikki on muita paksumpi. Normaalilla 230/400 V jännitteellä kolmivaiheiset voimapistorasiat ovat punaisia.

    Sähköautojen lataamista varten on kehitetty erityinen pistorasiatyyppi. Sen perusrakenne on samanlainen kuin edellä esitetyssä voimapistorasiassa. Siinä on viisi kosketinta (kolme vaihetta, nolla ja suojamaadoitus) ja lisäksi kaksi pienempää pilottikosketinta, joita voidaan käyttää kuormituksen ohjaukseen.

    Satakunnan ammattikorkeakoulun (SAMK) STEKin rahoituksella tekemiä ohjeita tavallisellekin sähkönkäyttäjälle sallittuihin sähkötöihin.

  4. Tomi Engdahl says:

    Kolmivaihevirta estradivalaisussa
    - Case “Vihan päivät 1918″

    Tämä tutkintotyö keskittyy sähkö- ja järjestelmäsuunnittelun kannalta merkityksellisiin
    seikkoihin estradivalaisussa. Tarkoitus on selvittää sähkön signaalitie sen syntypaikasta
    generaattorilta himmentimeen ja siitä edelleen valonheittimelle.

    Estradivalaisussa käytettävien valonheittimien nimellisjännite Suomessa on lähes aina
    230 V. Valaisimet ovat toisin sanoen yksivaiheisia. Tämä tarkoittaa sitä, että ne saavat
    käyttöjännitteensä yhden vaiheen ja nollan väliltä. Usein konventionaalistaen
    valonheittimien valotehoa halutaan säätää, joten yleensä ne on kytketty himmentimeen.

    Koska estradivalaisussa tarvittava sähkön määrä on usein verrattain suuri, on järkevää
    käyttää tässäkin sähkönjakelussa kolmivaihevirtaa. Kolmivaihesyöttöjä on kolmea eri
    kokoa. Syötön sulakkeiden mukaan on mitoitettu johtimien poikkipinta-alat sekä
    liittimien kestävyys. Suomessa syöttöjen koot ovat 3 · 16A, 3 · 32A, 3 · 63A ja 3 · 125A.
    Syöttöjä suojaavien sulakkeiden koot ovat edellä mainuttuja vastaavat, jos ei syötöille
    sähkökeskuksella olla jostain syystä vaihdettu pienempiä sulakkeita. Suomessa
    käytettävät voimavirtapistorasiat ja voimavirtapistotulpat ovat CEE standardin

    On hyvä aina käydä itse esityspaikalla varmistamassa sähkösyötöt, jos on pienintäkään
    epäilystä niistä tiedon toimittaneen henkilön asiantuntevuudesta. Kannattaa myös etsiä
    käsiinsä sähkösyöttöjen sulakkeet mahdollisten ylikuormitus- ja vikatilateiden varalta.

    Sulakkeita tarkastellessa kannattaa myös muistaa,
    että 32A voimavirtasyötön sulakkeet voivat olla
    keraamiset tai automaattivarokkeet.
    Keraamiset sulakkeet ovat aina
    25 ampeeriset ja automaatit yleensä 32 ampeerisia.
    Tosin automaattisulakkeita löytyy myös 25

  5. Tomi Engdahl says:

    Perilex and pre-IEC 60309
    plugs and sockets (mainly German)

  6. Tomi Engdahl says:

    About UK power

    Ring circuit

    In electricity supply design, a ring circuit is an electrical wiring technique in which sockets and the distribution point are connected in a ring. It is contrasted with the usual radial circuit, in which sockets and the distribution point are connected in a line with the distribution point at one end.

    This design enables the use of smaller-diameter wire than would be used in a radial circuit of equivalent total current capacity. The reduced diameter conductors in the flexible cords connecting an appliance to the plug intended for use with sockets on a ring circuit are individually protected by a fuse in the plug. Its advantages over radial circuits are therefore reduced quantity of copper used, and greater flexibility of appliances and equipment that can be connected.

    The ring final circuit concept has been criticized in a number of ways compared to radials, and some of these concerns could explain the lack of widespread adoption outside the United Kingdom.

    The installation tests required for the safe operation of a ring circuit are more time-consuming than those for a radial circuit

    Regulation 433-02-04 of BS 7671 requires that the installed load must be distributed around the ring such that no part of the cable exceeds its rated capacity. In some cases this requirement is difficult to guarantee

    In a ring circuit, if any poor joint causes a high resistance on one branch of the ring, current will be unevenly distributed, possibly overloading the remaining conductor of the ring.

    Ring circuits can occasionally generate unwanted magnetic fields.


    Ringmains = Good
    The Advantages of the 32A Ring Final Circuit ©IEE/Miet 2007.

    The 230 volt ring circuit has been with us now in excess of 60 years. It was developed after the Second World War to minimise the use of copper in the massive reconstruction that followed the conflict. It was one of those simple ideas that now seems obvious, yet at the time was innovative.This installation methodology was introduced in 1947 following many years of debate which began in June 1942

    The advantages are clear. To feed a given number of socket outlets using a ring main requires less copper and fewer protective devices. The benefits, however, do not stop there. The concept of the BS 1363 fused plug allows the devices connected to the ring to be appropriately protected on an individual basis. The standard fuses available are 13A, 5A & 3A

    2.1 Domestic Premises:
    All these devices are economically catered for and protected by the 32 amp ring main and BS 1363 fused plug. It is now the trend that the devices are supplied with a molded plug fitted with the appropriate fuse.The 32A ring main has stood the test of time and is well placed to serve the needs of our homes for the foreseeable future.

    2.2 Commercial Premises:
    Designers are continuing to use ring circuits to support small power requirements in offices where the power requirements are moderate and a benefit can be gained from the use of rings. 20A or 32A radial circuits are seldom used in the UK.

    2.3 Retail Premises:
    A mixture of ring and radial circuits are used dependent on the consequences arising from circuit failure. Freezers in a supermarket are fed individually from the distribution board to minimise losses on circuit failure. Designers will generally use ring mains for non – critical circuits.

    3.0 Operational Experience:

    The UK has been using the 230 volt 32A ring system to meet the small power requirements of a wide range of buildings for over 60 years. It is sensible to look at the experience we have gained to see if the system can be improved to advantage.Experience indicates few problems. The test procedures ensure that all circuit conductors are properly connected and that no bridges exist across the ring.
    The Wiring Regulations “Onsite Guide” describes the how the tests should be carried out and also defines the parameters governing the use of the circuit,such as area to be served and number of sockets allowed. An unlimitednumber of sockets are allowed in any 100 sq m area.4.0 Potential Faults. There are potential installation faults, which are caught by the test procedures.

    4.1.1 Live or neutral cable.If either the live or neutral cable is discontinuous at any one point, the ring will still function at all outlets, but the circuit is now two parallel feeders connected to a 32A protective device.If the break is at the centre of the ring and the load is distributed evenly around the ring there would be little problem. If, however, the break is towards one end of the ring, one cable will be taking the majority of the load current and risks over load. Testing in accordance with recommended procedures will find any break in the ring and allow remedial action to be taken.

    4.1.2 Earth Continuity Cable If the earth continuity cable is disconnected at a point around the ring, there will still be earth continuity at each socket. To this extent the ring is safer than the radial circuit. Loss of an earth continuity conductor on a radial circuit may not be noticed until a shock is received.
    4.2 Bridging. If a bridge is introduced across a ring circuit, the cost efficiency of the installation is diminished and current is shared between two parallel paths.This is not dangerous in normal use but could cause problems to a nun suspecting electrician working on the circuit in the future. Again testing will identify any such error.

    Ringmains = Bad

    Ring Circuits – The Disadvantages by Roger Lovegrove Introduction

    Have we got it right or is this yet another UK outdated insular custom? In this paper I intend to show you the disadvantages of using ring circuits.

    Having read David’s paper, it seems to me that the introduction of ring circuits was almost an afterthought and that the original intention was for a socket to be used on a radial circuit. In my view it should have stopped at domestic premises.

    However, over the years people have been brainwashed into believing that 13A sockets mean ring circuits

    Ring circuits are used almost everywhere in this country, and some others:Schools – laboratories and workshops Offices both large and small Hospitals – wards and surgical/treatment areas Retail premises, although some will not have ring circuits because of additional dangers and costs. Public buildingsAs well as Domestic At this point I would like to make it clear that I am not against ring circuits, there is aplace for them in modern installations provided they are properly designed inaccordance with BS 7671, carefully installed and tested as detailed in IEE Guidancenotes 3 or the On-Site Guide. If all three were properly applied some of the disadvantages would disappear.

    Main Issues.
    Safety is the main issue and safety being important becomes one of the main disadvantages. Ring circuits are misused and abused. They are installed without proper consideration as to their purpose and loading, additional points are frequently added as spurs without considering the existing layout of the circuit.They are used for heating circuits and IT circuits again, without considering the load or the need for secure protective conductor connections or reinforced cpcs.The ring circuits cost more to install than two radial circuits. Regulations – 433-02-04BS 7671. There are only four regulations that state requirements for ring circuits.The critical regulation is 433-02-04 which is probably largely ignored because it isoften impractical to apply. This regulation requires the load to be distributed aroundthe circuit so that the current in any part of the ring does not exceed the installedrating of the cable.

    Not easy to achieve. Regulation 543-02-09Regulation 543-02-09. This regulation requires the protective conductor of a ring circuit to be wired in the form of a ring, unless it is formed by metal covering or ametal enclosure. Most people ignore the metal covering part and run separate cpcs for each circuit.

    Hence metal trunkings become half filled with green and yellow cables that are unlikely to ever see an amp in their whole existence. Disadvantage: Waste of cable and labour.Safety Many rings are wired incorrectly particularly by DIY persons. Sometimes however electricians can get it wrong.

    A lack of understanding of the system is another problem. Unless a ring circuit is wired correctly with spurs restricted to 1 double point per spur,there is an increased fire risk due to overheating of cables and connections.If there are breaks in the conductors or loose connections in terminals there are both fire and shock risks.Testing The safety of a ring circuit relies on proper testing. It is a vital part of the installation process. If the correct testing method is not fully applied defects with the circuit are unlikely to be identified and corrected. This applies to both initial testing as well as periodic inspection and testing.Testing is however a time consuming and expensive operation, hence it is very often not done fully

    If the text had said that the highest value of resistance measured between phase and neutral, or cpc, with the conductors joined at the distribution board, should be a quarter of the sum of the conductor resistances added together, and all other points would be of lesser value, it would have saved the industry a great deal of unnecessary work time and cost.
    Happily this method was changed for the 16th edition.The 16th Edition Method.The recommended and only proven method of testing involves breaking the ring,separating the conductors at either the distribution board or at a point, doing the tests and re-assembling the circuit after completing the tests. How can one be sure that the ring is complete after reassembly? Still a funny way of doing things! Is this a disadvantage? In many instances, probably most, ring circuits are not properly tested.

    ypical Faults Found

    The most dangerous fault:
    Cross connections between two ring circuits or a ring and a radial so that the over-current and fault current protection is compromised becoming as much as 60 or 64 amps, disconnection times are completely blown and circuit isolation relies on 2 devices rather than a single device. Interconnections occur usually in distribution boards but can easily occur when ring circuits cables are installed in trunkings.

    ther Faults
    Incomplete ring on one or all circuit conductors – broken loops Part of a ring missing, a link cable having been left out, resulting in two 2.5mm2
    cables being protected by a single 32 A protective device

    Loose Connections due to conductors crammed into back boxes that are too small, especially for spurs, one cable not secured and overcrowded distribution boards.
    Too many spurs on a ring, and spurs on spurs – risk of over-heating
    Spur cables too long.

    Overheating likely to cause a hot spot at a termination that may eventually burn out or cause a fire.
    Break or bad connection in the cpc due to loose screws or over zealous tightening, thus increasing Zs of the circuit so that the limiting value is
    exceeded and the 0.4 second disconnection time is not achieved.
    Incorrect polarity. All these could cause danger and are therefore serious disadvantages. They would be eliminated by applying the correct testing methods.
    Testing ring circuits can take 5 or 6 times longer than testing radial circuits, and if any of the above defects are present fault finding can take a considerable time and become very expensive. Fault finding on radial circuits is relatively simple and quick.

    Big disadvantage to the installer. Who pays in the long run?
    Disadvantages galore, can’t happen with radials Installation
    Consider the disadvantages with circuit wiring:
    A 32A ring circuit serving 100m2 uses more cable and therefore takes longer to install
    than 1 x 32 A radial circuits serving 100m2
    A 32A ring circuit serving 100m2 uses more cable and therefore takes longer to install
    than 2 x 20A radial circuits each serving 50m2 the latter having a higher loading
    capacity of 40A.
    Ring circuits wired with 3 single core 2.5 mm2 cables drawn into a straight run of
    conduit or trunking take much longer to install than radial circuits wired with 3 single
    core 4.0 mm2 cables.
    Each of these situations use less of the worlds resources of copper.
    To my mind, in offices, workshops, classrooms and laboratories the only justification
    for installing a ring circuit is where a single circuit is run completely around the room.
    If it is necessary to install all 6 conductors in a single run of conduit or trunking then 2
    radial circuits are much more practical and cost effective.
    I have discussed this with many engineers who all agree with this philosophy. I know
    that some engineers will not consider using ring circuits in commercial installations.
    Additional points. Domestic and commercial consumers have a multitude of low-current
    appliances. New installations need many sockets and flexibility is needed to
    allow furniture to be moved around and for future alterations and additions.
    Extending or breaking into a ring circuit is not a straight forward exercise.
    Many domestic ring circuits have been modified incorrectly by DIY persons
    and are no longer a ring and are probably unsafe.
    More often than not, particularly in domestic premises, additional points are installed
    as spurs from the ring or spurs from spurs, with total disregard for the existing load
    and usage. This can, depending on the load, change the balance of the circuit.

    Unless thorough testing is carried out on a new or particularly a modified ring
    circuit, wiring faults may go undetected and invalidate the basic safety
    principles of the system.
    Another potential danger and disadvantage.
    It has been said many times that if electricians are trained properly the problems
    would not exist. I do not disagree with that. An apprentice who is brought up with the
    system should understand the correct installation methods, however testing is a
    different issue.

    We have big labour problems in this country. There is a dearth of competent home
    grown time served electricians.
    Much of our labour comes from agencies and you get what you are sent. In London
    you hardly ever hear English spoken on construction sites. Electricians trained in EU
    countries other than Ireland will not have heard of ring circuits. They may be very
    good competent tradesmen in their own countries but never-the-less are not competent
    to install socket circuits in this country.
    Europeans do not understand ring circuits. This also applies to Australians, New
    Zealanders and South Africans many of whom come to this country to make a

    It is
    hardly surprising that there are problems. In these circumstances independent testing
    is essential, but is it done? It becomes expensive for the contractor and ultimately the

    IEE Guidance Notes show radial circuits in the conventional circuit arrangements.
    • 32 A ring – 7 kW – 100 m2
    • 32 A radial – 7 kW – 100 m2
    • 20 A radial – 4.5 kW – 50 m2
    In my view
    • 2 x 20A radials better than 1 x 32A ring
    A 20 A circuit to serve 50 m2 floor area and a 32 amp circuit, 100 m2. These are
    based on the maximum anticipated load in these areas not exceeding 5 kW or 7 kW
    The limiting factor in such areas is the cable length – voltage drop and the earth loop
    impedance of the circuit. Voltage drop is unlikely to be a problem neither will earth
    loop impedance because in the near future all such circuits will require RCD
    protection. The limiting factor need only be the maximum anticipated load that would
    be used in the area. It is now recommended that kitchens are treated as a separate entity and have at
    least one ring circuit. 2 x 20 A radial circuits in a kitchen will use less cable than a ring circuit and
    provide greater capacity as long as care is taken to ensure that fixed loads such
    as washing machines, driers etc are not all on one circuit.

    A tree circuit is simply a radial circuit with branches. A 20 A tree circuit wired with
    2.5 mm2 cables would be far more versatile than a straight radial circuit and probably
    far more practical.

    Typically a standard 3 bedroom domestic property could be adequately served by
    2 x 20 A 2.5 mm2 radial or tree circuits, and
    1 x 32 A 4.0 mm2 radial or tree circuit in the kitchen.

  7. Tomi Engdahl says:

    Average household items in Europe run on 230V 50 Hz AC protected with 10A or 16A breaker or fuse on mains panel. The house gets power from efficient three phase feed. The special items that need more power than available from normal single phase outlet can provide usually use three phase power that is either permanently wired (for example stoves in Finland considered to be standard feature in apartment) or use an outlet in case they need to be easily plugged in/out (stoves in countries where people are bring their own, heavy machinery on construction, industrial machines, stage lights and PA on clubs etc. )

  8. Tomi Engdahl says:

    In radial wiring
    The typical wire thickness (for live, neutral and ground) is either 1.5 mm2 (for 10A circuits) and 2.5 mm2 (for 16A circuits). The extension cords typically are built using 1.5 mm2 cable. The cables feeding equipment are typically use 1.5 mm2, 1 mm2 or 0.75 mm2 wires depending on the power equipment uses.
    The equipment have fuse or other means that protects against overload situation. The device wire is thick enough that it will withstand short circuit situations so long time that the 10A or 16A breaker/fuse on the mains panel trips. The equipment wire does not work as fuse in this system.


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