Industrial and multiphase power plugs and sockets

They are generally used in polyphase systems, 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.

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).

To reduce the risk of users accidentally touching energized conductors and thereby experiencing electric shock, plug and socket systems often incorporate safety features in addition to the recessed slots or holes of the energized socket.

[9] Electrical sockets for industrial, commercial and domestic purposes generally provide two or more current carrying (live[10][11]) connections to the supply conductors.

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).

[16] Sockets intended for use with the American split Phase distribution system may have two line contacts and neutral.

Blue P+N+E sockets (generally 16 A, although 32 A is becoming more common) are used as standard by British and Danish campsites and yacht marinas 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 malls and their peripherals to power 'temporary' stalls not incorporated within a lock-up shop, there is also use in domestic gardens within Britain 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 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.

Where more current carrying capacity is required, such as between generator sets and distribution boards, VEAM Powerlocks or Cam-Loks may be used.

Where it is necessary to run separate feeds through multicable, the Socapex 19-pin connector is often encountered on theatre and studio lighting rigs.

The Swiss standard SN 441011 (until 2019 SEV 1011) Plugs and socket-outlets for household and similar purposes.

[19] defines a hierarchical system of plugs and sockets including both single and three phase connectors.

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 Europlug.

These have been replacing the American-style for some time and are much more likely to be found in food processing, data centers, healthcare, entertainment, and other industries.

Locking type connectors are found mostly in industrial applications and are not common in residential and light commercial use.

[citation needed] Twist-locking connectors all use curved blades that have shapes that conform to portions of the circumference of a circle.

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.

Having a distinct connector designated for dimmable power also helps prevent confusion of dimmed and non-dimmed circuits which could lead to equipment damage.

[24] California connectors are commonly used at outdoor events, shows and conventions and at construction sites.

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.

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.

In this series, multiple sizes of three-phase round-pin socket are standardized by current rating and neutral circuit.