Industrial and multiphase plugs and sockets provide a connection to the electrical mains rated at higher voltages and currents than household plugs and sockets. They are generally used in
polyphase system
A polyphase system is a means of distributing alternating-current (AC) electrical power where the power transfer is constant during each electrical cycle. AC phase refers to the phase offset value (in degrees) between AC in multiple conducting ...
s, with high currents, or when protection from environmental hazards is required. Industrial outlets may have weatherproof covers, waterproofing sleeves, or may be interlocked with a switch to prevent accidental disconnection of an energized plug. Some types of connectors are approved for hazardous areas such as coal mines or petrochemical plants, where flammable gas may be present.
Almost all three-phase power plugs have an
earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
(ground) connection, but may not have a
neutral
Neutral or neutrality may refer to:
Mathematics and natural science Biology
* Neutral organisms, in ecology, those that obey the unified neutral theory of biodiversity
Chemistry and physics
* Neutralization (chemistry), a chemical reaction in ...
because three-phase loads such as motors do not need the neutral. Such plugs have only four prongs (earth, and the three phases). An example of a socket with neutral is the L21-30 (30 A) and the L21-20 (20 A) both of which have five pins (earth, neutral, and X, Y, Z phases).
While some forms of power plugs and sockets are set by international standards, countries may have their own different standards and regulations. For example, the colour-coding of wires may not be the same as for small mains plugs.
Concepts and terminology
Generally the plug is the movable connector attached to an electrically operated device's mains cable, and the socket is fixed on equipment or a building structure and connected to an energised electrical circuit. The plug has protruding pins or, in US terminology, blades (referred to as ''male'') that fit into matching slots or holes (called ''female'') in the sockets. A plug is defined in IEC 60050 as an ''accessory having pins designed to engage with the contacts of a socket-outlet, also incorporating means for the electrical connection and mechanical retention of flexible cables or cords'', a plug does not contain components which modify the electrical output from the electrical input (except where a switch or fuse is provided as a means of disconnecting the output from input). In this article, the term 'plug' is used in the sense defined by IEC 60050. Sockets are designed to prevent exposure of bare energised contacts.
To reduce the risk of users accidentally touching energized conductors and thereby experiencing
electric shock
Electrical injury is a physiological reaction caused by electric current passing through the body. The injury depends on the density of the current, tissue resistance and duration of contact. Very small currents may be imperceptible or produce ...
, plug and socket systems often incorporate safety features in addition to the recessed slots or holes of the energized socket. These may include plugs with insulated sleeves, recessed sockets, sockets with blocking shutters, and sockets designed to accept only compatible plugs inserted in the correct orientation.
The term ''plug'' is in general and technical use in all forms of English, common alternatives being ''power plug'',
''electric plug'',
and (in the UK) ''plug top''.
The normal technical term (in both British and International English) for an AC power socket is ''socket-outlet'',
but in non-technical common use a number of other terms are used.
In British English the general term is ''socket,'' but there are numerous common alternatives, including ''power point'', ''plug socket'',
''wall socket'',
and ''wall plug''.
In American English ''receptacle'' and ''outlet'' are common, sometimes with qualifiers such as ''wall outlet'', ''electrical outlet'' and ''electrical receptacle'', all of these sometimes to be found in the same document.
Electrical sockets for industrial, commercial and domestic purposes generally provide two or more current carrying (live) connections to the supply conductors. These connections are classified as poles. A pole will be either a neutral connection or a line
Neutral is usually very near to earth potential, usually being earthed either at the distribution board or at the substation. Line (also known as ''phase'' or ''hot'', and commonly, but technically incorrectly, as ''live'') carries the full supply voltage relative to the neutral (and to earth).
Single phase sockets are classified as two pole (2P) and provide a single line contact and a neutral contact. In addition, a protective earth (Ground in American terminology) contact is usually, but not always, present, in which case the socket is classified as two pole and earth(2P+E).
Three phase sockets provide three line contacts, they may also include either or both of a neutral and protective earth contact. The designations of the three contacts may vary. The IEC standards use the Line designations L1, L2 and L3. NEMA standards use the Phase designations X, Y and Z.
Sockets intended for use with the American
split Phase
A split-phase or single-phase three-wire system is a type of single-phase electric power distribution. It is the alternating current (AC) equivalent of the original Edison Machine Works three-wire direct-current system. Its primary advantage is th ...
distribution system may have two line contacts and neutral. In this case the line designators X and Y are used. They may also include a protective earth contact.
Europe
IEC 60309 system
In Europe, the most common range of heavy commercial and industrial connectors are made to IEC 60309 (formerly IEC 309) and various standards based on it (including BS 4343 and BS EN 60309-2). These are often referred to in the UK as CEE industrial, CEEform or simply CEE plugs, or as "Commando connectors" (after the MK Commando brand name for these connectors).
The maximum voltage rating of IEC 60309 connectors is 1000 V DC or AC; the maximum current rating is 800 A; and the maximum frequency 500 Hz. Plugs are available in P+N+E (unbalanced single phase with neutral), 2P+E (balanced single phase), 3P+E (3 phase without neutral), and 3P+N+E (three phase with neutral). Current ratings available include 16 A, 32 A, 63 A, 125 A and 200 A.
Voltage rating and other characteristics are represented by a colour code (in
three-phase
Three-phase electric power (abbreviated 3φ) is a common type of alternating current used in electricity generation, Electric power transmission, transmission, and Electric power distribution, distribution. It is a type of polyphase system empl ...
plugs the stated voltage is the phase-phase voltage, not the phase-neutral voltage). Plugs have the earth pin of a larger diameter than the others, and located in different places depending on the voltage rating, making it impossible to mate, for instance, a blue plug with a yellow socket. Since the different current ratings have different overall sizes, it is also not possible to mate different pin configurations or current ratings. For example, a 16 A 3P+E 400 V plug will not mate with a 16 A 3P+N+E 400 V socket and a 16 A P+N+E 230 V plug will not mate with a 32 A P+N+E 230 V socket.
Yellow 2P+E, blue P+N+E, yellow 3P+E, red 3P+E, and red 3P+N+E are by far the most common arrangements. Blue P+N+E sockets (generally 16 A, although 32 A is becoming more common) are used as standard by
British
British may refer to:
Peoples, culture, and language
* British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies.
** Britishness, the British identity and common culture
* British English, ...
and
Danish
Danish may refer to:
* Something of, from, or related to the country of Denmark
People
* A national or citizen of Denmark, also called a "Dane," see Demographics of Denmark
* Culture of Denmark
* Danish people or Danes, people with a Danish ance ...
campsite
A campsite, also known as a campground or camping pitch, is a place used for overnight stay in an outdoor area. In British English, a ''campsite'' is an area, usually divided into a number of pitches, where people can camp overnight using te ...
s and
yacht
A yacht is a sailing or power vessel used for pleasure, cruising, or racing. There is no standard definition, though the term generally applies to vessels with a cabin intended for overnight use. To be termed a , as opposed to a , such a pleasu ...
marina
A marina (from Spanish , Portuguese and Italian : ''marina'', "coast" or "shore") is a dock or basin with moorings and supplies for yachts and small boats.
A marina differs from a port in that a marina does not handle large passenger ships o ...
s to provide 240 V domestic mains power to frame-tents, trailer-tents, caravans, and boats; they are also used elsewhere in Europe for the same purpose, though in some countries the local domestic plug is also widely used. Static caravans generally use the similar 32 A version because of the requirement to power electrical cooking and heating appliances. The blue P+N+E 16 A version carrying 240 V is also used in
shopping mall
A shopping mall (or simply mall) is a North American term for a large indoor shopping center, usually anchored by department stores. The term "mall" originally meant a pedestrian promenade with shops along it (that is, the term was used to refe ...
s and their peripherals to power 'temporary' stalls not incorporated within a lock-up shop, there is also use in domestic gardens within
Britain
Britain most often refers to:
* The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands
* Great Britain, the largest island in the United King ...
to power garden equipment, barbecues, and temporary lighting. The yellow 2P+E 16 A version carrying 115 V is used extensively on the
London Underground
The London Underground (also known simply as the Underground or by its nickname the Tube) is a rapid transit system serving Greater London and some parts of the adjacent ceremonial counties of England, counties of Buckinghamshire, Essex and He ...
railway system to power temporary usage of heavy-duty fans; it is also frequently used by tradesmen within the UK, built into a portable transformer box that is powered from a standard 13 A 240 V mains supply, to run heavy-duty power-tools designed to operate at 115 V.
A small number of marinas provide 230 V single-phase power through a red three-phase connector (breaking the relevant standards in the process). This goes some way to ensuring that only boats that have paid the required fee (and thus obtained an appropriately made-up adaptor cable) are able to use the electricity.
For more detailed information, see the main article
IEC 60309
IEC 60309 (formerly IEC 309 and CEE 17, also published by CENELEC as EN 60309) is a series of international standards from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purpo ...
.
Entertainment industry
Throughout Europe, a common use of industrial power connectors is in the entertainment and broadcast industries.
In this industry the above-mentioned
IEC 60309
IEC 60309 (formerly IEC 309 and CEE 17, also published by CENELEC as EN 60309) is a series of international standards from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purpo ...
connectors are referred to as ''CEEform'' (or just CEE) connectors. 230 V single-phase (blue) and 400 V three-phase (red) connectors between 16 A and 125 A ratings are used.
Where more current carrying capacity is required, such as between generator sets and distribution boards, VEAM
Powerlock
Powerlock is a range of single-pole electrical connectors used for temporary high-current, low-voltage (up to 1000 V AC) applications, similar to but considered safer than camlock connectors. Originally developed by Litton Veam in the mid-199 ...
s or Cam-Loks may be used. These connectors are single pole so five are required to accommodate all three phases, neutral and ground. Powerlocks have a rating of 400 A or 660 A at 1 kV. Cam-Lok E1016 Series are rated at 600 V 400 A.
Powerlocks are identified with the European harmonized colour code, they are also annotated as follows:
*
*
*
*
*
Cam-Loks are also available in these colours.
Where it is necessary to run separate feeds through
multicable
{{Globalize, date=February 2018
In stage lighting, a multicable (otherwise known as multi-core cable or mult) is a type of heavy-duty electrical cable used in theaters to power lights. The basic construction involves a bundle of individual conduc ...
, the
Socapex
Socapex is a brand of electrical connectors, known in the entertainment industry primarily for their 19-pin electrical connectors, commonly known as Socapex connectors, and used in film, television, and stage lighting to terminate the ends of a ...
19-pin connector is often encountered on theatre and studio lighting rigs.
UK: Lewden plugs
Lewden plugs and sockets are metal bodied waterproof plugs and sockets made by Lewden. The pin arrangements of the smaller single phase varieties are the same as
BS 1363
Plugs and sockets for electrical appliances not hardwired to mains electricity originated in the United Kingdom in the 1870s and were initially two-pin designs. These were usually sold as a mating pair, but gradually de facto and then officia ...
and
BS 546
Plugs and sockets for electrical appliances not hardwired to mains electricity originated in the United Kingdom in the 1870s and were initially two-pin designs. These were usually sold as a mating pair, but gradually de facto and then officia ...
plugs and sockets. These plugs and sockets will mate with normal plugs and sockets of the same pin arrangement but they are only waterproof when a Lewden plug is used in a Lewden socket and the screw ring is properly tightened (sockets have a metal cover that screws on to waterproof them when not in use).
UK: BS 196
In 1930, the BS 196 standard for industrial plugs and sockets was introduced. The plugs are available in 5 A, 15 A and 30 A variants, with various configurations of keyways and pins to cater for different voltages. BS 196 plugs have now been superseded by BS 4343 ( CEE type) connectors in most modern applications.
Sweden, Germany and Netherlands: Perilex plugs
Perilex plugs and sockets are 5-pin 3-phase connectors. The system provides 400 V 3P+N+ PE and exists in 16 A and 25 A versions. In Sweden, the 16 A is generally used for stoves and to some extent for other heating devices in kitchens.
In the Netherlands, Perilex is also used to connect fans with wired speed control (Switched L2 and L3 pins), but fans may not use three phase power
Sweden: Semko 17 plugs
Semko 17 were 3/4-pin 3-phase connectors, with (4-pin) or without (3-pin) a neutral connector. Earth were provided via the shield. The connectors were available in different sizes, 16 A with rounded corners; 25 A and 63 A were rectangular. These connectors were used mainly in industrial and agricultural installations. Manufacturing and selling of Semko-17 connectors with metal shells was prohibited in 1989. A few years later manufacturing and selling of all Semko-17 connectors were prohibited. Existing connectors may be used but not by any employee (prohibited by "Arbetsmiljöverket"). The reason for the prohibition is that Semko-17 had several safety issues. The ground connection can become oxidized and when the shells are made of metal any ground fault goes right through the hands of a person connecting/disconnecting a male and a female cable connector (unless the person wears insulating gloves). Incorrect use of the ground connector as a neutral was not uncommon. Perhaps the worst issue is that in some connectors the ground screw could rust so severely that the ground wire comes loose and in the worst case make contact with a line (phase) wire nearby.
Switzerland: SN 441011
The Swiss standard ''SN 441011'' (until 2019 ''SN SEV 1011'') ''Plugs and socket-outlets for household and similar purposes''. defines a hierarchical system of plugs and sockets including both single and three phase connectors. Sockets will accept plugs with the same or fewer number of pins and the same or lower ratings. Single phase Swiss plugs and sockets are described in the main article
SN 441011
SN 441011, until 2019 SEV 1011, is the Swiss national standard for AC power plug for domestic use and similar purposes. The plug ''SN 441011 Type 12'' and the socket ''SN 441011 Type 13'' are also known internationally as Type J.
Details
Th ...
.
The type 15 plug and socket has 3 round pins of 4 mm diameter, plus 2 flat pins (for L2 and L3). It is designed for three phase applications and is rated at 10 A, 250 V/440 V. The socket will also accept types 11 and 12 plugs, and the
Hubbell Incorporated
Hubbell Incorporated is an American company that designs, manufactures, and sells electrical and electronic products for non-residential and residential construction, industrial, and utility applications. Hubbell was founded by Harvey Hubbell a ...
to this day, although the term tends to be used generically to refer to NEMA twist-locking connectors manufactured by any company. Twist-locking connectors all use curved blades that have shapes that conform to portions of the circumference of a circle. Once pushed into the receptacle, the plug is twisted and its now-rotated prongs latch into the receptacle. To unlatch the plug, the rotation is reversed. The locking coupling makes for a very reliable connection in commercial and industrial settings.
Like non-locking connectors, these come in a variety of standardized configurations and follow the same general naming scheme except that they all begin with an ''L'' for ''locking''. The connector families are designed so that 120 V connectors, 208/240 V connectors, and various other, higher-voltage connectors can not be accidentally intermated.Hubbell Twist-Lock Wiring Devices and Safety Enclosures /ref>
Stage pin connectors
A ''
stage pin connector
A stage pin connector, also known as a grounded stage pin (GSP) or grounded pin connector (GPC), is a standard cable type for theatrical lighting in North America and in many countries in the theatre world.Richard Cadena, ''Electricity for the En ...
'' (SPC), or ''grounded stage pin'' (GSP), is a connector used primarily in the
theatre
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...
industry for
stage lighting
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts.
applications in the United States. Stage pin connectors are generally used for conducting dimmed power from a
dimmer
A dimmer is a device connected to a light fixture and used to lower the brightness of the lighting, light. By changing the voltage waveform applied to the lamp, it is possible to lower the luminous intensity, intensity of the light output. Alt ...
to
stage lighting
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts.
instruments, although occasionally they can power other equipment.
The primary advantage of the stage pin connector over the NEMA 5-15 connector (commonly known as an Edison connector in the theatre industry) is its increased durability and resistance to damage due to its more robust construction and the ability to compensate for wear with a pin splitter. Having a distinct connector designated for dimmable power also helps prevent confusion of dimmed and non-dimmed circuits which could lead to equipment damage. Even the smallest stage pin connectors are rated for 20 A, which translates to 2.4 kW at 120 V, compared to the 15 A and 1.8 kW of the NEMA 5-15. In applications where cables are on the floor, the low profile of the connector allows for connections that are only slightly higher than the cables they connect.
California 50 A Connector
In North America for moderate current requirements the 50 A California-style connector, also known as CS6364 and CS6365 is commonly used. It features a
twist-lock
A twistlock or twist lock, together with matching corner castings, as defined in norms including ISO 1161:1984, form a standardized (rotating) connector system, for connecting and securing intermodal, and predominantly ISO-standard internatio ...
design with a metal sleeve full protecting the blades on the male connector and a center ground spike on the female connector to aid in centering.
California connectors are commonly used at outdoor events, shows and conventions and at construction sites. The connector gets its name from being developed as a safer connector during the early days of Hollywood film studios in California. The first high-current connectors used in the studios were stage pin (also referred to as "paddle plugs") used in theaters, which were not grounded. The California plug, however, is grounded by the outer steel shroud. This also helped protect the male contact pins from damage from the constant dragging of cables around a set throughout the day. The grounded shroud helps absorb the arc-flash if the connector is plugged or unplugged while energized. The original paddle plugs were known for dangerous arc-flashes, especially in the older DC-powered theaters in the early years of electrical stage lighting.
For example, a three phase plug which requires a neutral connection cannot be inserted into a socket outlet which does not provide for such a connection. However, a plug which does not require a neutral connection can be inserted into a socket outlet which provides such a connection, although the neutral connection would not be utilized in that situation.
For
stage lighting
Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts.
use, a common plug is the 32-A 5-pin connector with a neutral pin. Motor loads that don't need the neutral use a four-pin connector. Larger requirements may use powerlock or camlock connectors. In the IT industry, the
IEC 60309
IEC 60309 (formerly IEC 309 and CEE 17, also published by CENELEC as EN 60309) is a series of international standards from the International Electrotechnical Commission (IEC) for "plugs, socket-outlets and couplers for industrial purpo ...
system is sometimes used.
Australia
In Australia, New Zealand and many associated South Pacific island nations, the AS/NZS 3123 standard is used. In this series, multiple sizes of three-phase round-pin socket are standardized by current rating and neutral circuit. Each socket within a group accepts plugs in the same group up to its rating, but excludes plugs with a higher current rating, from a different group, or with a neutral pin (if there is not one in the socket). Multiphase plugs and sockets are rated at up to 500 V and all include an earth connection. These plugs and sockets are usually IP56 rated if fitted correctly. A screw collar helps hold plug and socket together.
In the single-phase standard
AS/NZS 3112
AS/NZS 3112 is the harmonised Australian and New Zealand standard for AC power plugs (male) and sockets (female). The standard is used in Australia, Argentina, New Zealand, Fiji, Tonga, Solomon Islands, Papua New Guinea and several other Pacifi ...
used in residential environments, plugs of lower current rating may be inserted into single phase socket outlets of higher current rating but not vice versa. While this feature is somewhat reflected with multiphase sockets, it is further limited to only plugs within the same group. For example, there is one group that consists of 32 A, 40 A and 50 A connectors, and another group of 50 A, 63 A and 80 A connectors. The 32 A plug can be connected to any of the 32 A, 40 A or 50 A sockets in the first group, however it cannot be connected to any of the 50 A, 63 A or 80 A sockets in the second group. The standard notes that there are two different, incompatible 50 A connectors that are not interchangeable as they are physically different sizes.
Compatibility is grouped like this, such that larger sockets in one group can take the same plug or any smaller plugs from that group only:AS/NZS 3123 /ref>
Each of the three phase plugs and sockets are available as 4-pin (without neutral) or 5-pin (with neutral). A plug without a neutral pin can be inserted into a socket carrying neutral, but the reverse is not possible as the neutral pin blocks insertion into a socket that does not have a hole for the neutral conductor.
From this it can be seen that, for example, installing a 32 A, 250 V socket will only be compatible with a 32 A plug and it will not be possible to insert 10 A or 20 A plugs.
Within each size group, the plugs and sockets are keyed with certain "lugs" protruding on the outside of the plugs. Higher current plugs have more lugs to prevent them from being inserted into a lower current socket outlet, while still allowing them to be inserted into a socket outlet of the same size group rated for a higher current. For example, a 32 A 4-pin plug without neutral can plug into a 50 A 5-pin socket with neutral available.
However a 10 A 5-pin plug cannot fit a 32 A 5-pin socket, as the plugs are in different groups and not only are their diameters different, but the position of the conductors also varies by a few degrees (for example the group 7/8 32 A plug has its L and N pins at 9 o'clock and 3 o'clock, while the group 1/2 20 A plug has its L and N pins at 10 o'clock and 2 o'clock instead.)
There are also metal clad plugs and sockets that go up to 63 A ratings, at a significantly higher cost.
See also
*
Domestic AC power plugs and sockets
AC power plugs and sockets connect electric equipment to the alternating current (AC) mains electricity power supply in buildings and at other sites. Electrical plugs and sockets differ from one another in voltage and current rating, shape, si ...
*
Double insulated
Appliance classes (also known as protection classes) specify measures to prevent dangerous contact voltages on unenergized parts, such as the metallic casing, of an electronic device. In the electrical appliance manufacturing industry, the followi ...
*
Electricity
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
*
Electrical power
Electric power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second. Standard prefixes apply to watts as with other SI units: thousands, millions and billions of ...
*
Ground and neutral
Ground and neutral are circuit conductors used in alternating current electrical systems. The ground circuit is connected to earth, and neutral circuit is usually connected to ground. As the neutral point of an electrical supply system is often ...
*
Protective multiple earthing
An earthing system (UK and IEC) or grounding system (US) connects specific parts of an electric power system with the ground, typically the Earth's conductive surface, for safety and functional purposes. The choice of earthing system can affec ...
*
SAE J1772
SAE J1772, also known as a J plug or Type 1 connector after its international standard, IEC 62196 Type 1, is a North American standard for electrical connectors for electric vehicles maintained by SAE International under the formal title "SAE Sur ...
- Single phase AC and optional DC
Electric Vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...
charging
*
Type 2 connector
The IEC 62196-2 Type 2 connector (often referred to as Mennekes for the company that designed it) is used for charging electric vehicles, mainly within Europe, as it was declared standard by the EU. Based on widespread red IEC 60309 three phase pl ...
- Three phase AC and optional DC
Electric Vehicle
An electric vehicle (EV) is a vehicle that uses one or more electric motors for propulsion. It can be powered by a collector system, with electricity from extravehicular sources, or it can be powered autonomously by a battery (sometimes cha ...