Mains voltage

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World map of grid voltages and grid frequencies (as of 2015)
World map of the population's access to the low-voltage network (as of 2017) as a measure of electrification
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  • 60.1% -80%
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  • The electrical voltage made available by the energy suppliers in the power grids , which is used to transmit electrical power, is referred to as mains voltage . In the narrower sense, mains voltage is often understood to mean the level of the alternating voltage in the low-voltage networks, in contrast to the voltages in the high-voltage network .

    Low voltage


    The network voltage provided by the energy supplier (in Germany: distribution network operator ) at the network connection point is characterized by its. IEC 60038 (in Germany: DIN EN 60038 VDE 0175-1)

    In Europe, further characteristics of the voltage (frequency, height, curve shape and symmetry of the external conductor voltages) are specified in EN 50160 .



    Structure of the low-voltage network

    The mains voltage is usually distributed to the consumers in the low- voltage network with the following configurations in TN systems :

    • the three outer conductors (colloquial phases ) (L1, L2 and L3),
    • a neutral conductor (N) and
    • a protective conductor (PE = protective earth or potential earth )


    • the three outer conductors (phases) (L1, L2 and L3) and
    • a PEN leader . In this case, the neutral conductor and protective conductor are combined in a single conductor.

    In Europe, the mains voltage is 230 V ± 23 V with a mains frequency of 50  Hz ± 0.2 Hz.

    In three-phase systems , the effective value of the sinusoidal AC mains voltage between an outer conductor and the neutral conductor is 230  V , and between two outer conductors approx. 400 volts.

    North and South America

    In Canada, the USA, Mexico and some northern states in South America, the nominal value of the mains AC voltage is 120 V (previously 110 V). For larger consumers such as air conditioning systems, double the mains voltage of 240 V (previously 220 V) is also common. The mains frequency is 60 Hz. The low-voltage networks in these countries are implemented as a single-phase three-wire network; three-phase alternating current is often not available for smaller consumers; if it exists, the voltage is 208 or 415 V.

    In Brazil, depending on the region, 110 V, 127 V or 220 V are offered, each with 60 Hz. The southern countries Chile, Argentina, Bolivia, Paraguay and Uruguay have 220 V at 50 Hz.


    In the Japanese power grid , the line voltage of 100 V (regional 50 Hz or 60 Hz) has the lowest value in the world. in Taiwan the mains voltage is 110 V, in China, Hong Kong and Thailand it is 220 V (50 Hz). Like Europe, India has a 230 V network (at 50 Hz).


    Until 1987 the mains voltage was in much of Europe, including Germany, Austria and Switzerland , while it was in the United Kingdom . The voltage of , which has been valid in Europe since then , was specified as the standard voltage in the international standard IEC 60038 : 1983.

    From 1987 onwards there was a changeover in several stages . Since 2009 the line voltage has been allowed to be between 207 and 253 volts.

    Electrical loads specified for 220 volts could also be operated with the consideration of the tolerances valid from 1987 to 2009 without seriously violating the tolerance conditions: At the maximum voltage was 242 V. At the maximum voltage was 243.8 volts. This no longer applies since 2009, as the maximum voltage is now 253 V.

    With the minimum voltage, the tolerance band was not and is not violated: While 198 volts were permitted earlier, it is now at least 207 volts.

    Increasing the voltage by around 5% leads to an increase in performance in many devices. For devices whose function is based on the ohmic resistance , e.g. B. fan heater or kettle , the consumption increases quadratically in relation to the voltage increase, i.e. by about 10% of the power. In many cases, the amount of energy to be paid for remains roughly the same, since a kettle, for example, heats up the given amount of water faster and switches off earlier due to its higher performance.

    In the case of incandescent lamps , this increase is somewhat lower due to the usual PTC characteristics of the filaments. However, higher voltage also means lower energy losses on the lines if the same power is transmitted. In the case of incandescent lamps, however, a higher filament temperature leads to a shortening of the (statistically probable) operating time.

    Mains voltage fault

    The sinusoidal curve of the mains voltage is increasingly disturbed by non-linear consumers. These include gas discharge lamps , rectifiers, dimmers ( thyristor and triac controllers), frequency converters , compact fluorescent lamps and switched-mode power supplies without reactive power compensation (power factor correction, PFC).

    On January 1, 2001, an EMC standard came into force that stipulates regulations on the permissible low-frequency interference spectrum (harmonics) for electronic consumers from 75 watts.

    Also asynchronous motors cause net impurities, called Nutenpfeifen. It is created by the subdivision of the squirrel cage and the resulting AC voltage fed back into the network with a higher, speed-dependent frequency.

    The grid frequency is the requirements of today according to European interconnected system very strictly adhered to so that they can be used as a reference value, for. B. to control electrical clocks or for voltage-controlled inverters for feeding in solar power.

    Protection against contact

    Touching conductors carrying mains voltage can be life-threatening. The mains voltage is above the safety extra-low voltage or safety extra-low voltage . For this reason, protective measures against electric shock when touching live lines must be taken for both the supply lines and the devices operated with mains voltage .

    This includes protective insulation , protective grounding and protective separation , which prevent accessible conductive parts (e.g. housing) from assuming dangerous voltages in the event of a defect.

    Sockets must be secured against touching the live parts. To protect children, there are also child safety devices that are intended to prevent objects from being inserted into the openings of sockets .

    Medium voltage

    Larger consumers such as industrial companies or hospitals are usually connected directly to the medium-voltage network with voltages of 10 kV ( kilovolt ) or 20 kV via one or more in-house transformer stations .

    High voltage

    Even in high-voltage networks, standardized voltages are almost always used. The voltages 220 kV and 380 kV are mainly used in the extra high voltage network in Europe. The high-voltage network is usually operated at 110 kV, but there are also 60 kV networks (especially in large cities with older cable systems).

    In other areas, other voltage levels are sometimes common: in Russia there are extra-high voltage networks with 1150 kV, 750 kV, 500 kV and 330 kV, while the voltages in the extra-high voltage networks in the USA are 765 kV, and in Canada 735 kV, 500 kV and 345 kV be. A value of 132 kV is common for high-voltage networks in the USA.

    In the medium-voltage network, in addition to 20 kV, especially in urban areas, because of the older cable systems there, 10 kV are also common. In the high-voltage direct current , there is no standardized voltages.

    In traction current supply networks, the standard voltage in Germany and Austria is 110 kV, in Switzerland 66 kV and 132 kV.

    Traction current

    Catenary (16 Hz, 15 kV) of German design at Thayngen train station, Switzerland (2018) World icon

    Numerous tensions have prevailed in railway operations themselves ( overhead lines ). The following five systems dominate mainline railways (see list of traction current systems ):

    • Single-phase alternating voltage 50 Hz, 25 kV
    • Single-phase alternating voltage 60 Hz, 25 kV
    • Single-phase alternating voltage 16⅔ Hz, 15 kV (only Germany, Austria and Switzerland [all: with a few exceptions, since 1995: 16.7 Hz]; Norway, Sweden)
    • DC voltage 3 kV
    • DC voltage 1.5 kV (including France and the Netherlands [new high-speed lines: 50 Hz, 25 kV])

    The voltage is not standardized on trams and underground trains. In Germany, Austria and Switzerland, DC voltages of 500 V to 750 V are mostly used here.

    See also


    • CENELEC: EN 60038: 2012-04 CENELEC standard voltages . Beuth publishing house.
    • CENELEC: EN 50163: 2004-11 Railway applications - Supply voltages for railway networks . Beuth publishing house.

    Web links

    Commons : Mains electricity  - collection of pictures, videos and audio files

    Individual evidence

    1. Access to electricity (% of population). In: World Bank Open Data. World Bank , 2019, accessed October 28, 2019 .
    2. 0.2 Hz corresponds to the tolerance window that can be compensated by primary control.
    3. Voltage tolerances in the energy supply ( memento of the original from September 27, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Dipl.-Ing. Thomas Flügel at the Charité University Hospital, Division VII C 1 Electrical Engineering, viewed on December 7, 2006. @1@ 2Template: Webachiv / IABot /
    4. Short version of EN 50160 ( memento of the original from March 26, 2013 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed November 12, 2014. @1@ 2Template: Webachiv / IABot /
    5. Directive 85/374 / EEC (PDF) of the Council of 25 July 1985 on the approximation of the legal and administrative provisions of the member states on liability for defective products. This guideline also declared electricity to be a product for whose faults the producer can be held liable (see also Product Liability Act ).