Power cord

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Power cord, with plug at end, plugged into a Japanese outlet with ground post, for a washing machine. OutletPlug.jpg
Power cord, with plug at end, plugged into a Japanese outlet with ground post, for a washing machine.
North American power cord with IEC 60320 C13 appliance connector and NEMA 5-15 wall plug. U.S. power cord IEC 320.agr.jpg
North American power cord with IEC 60320 C13 appliance connector and NEMA 5-15 wall plug.

A power cord, line cord, or mains cable is an electrical cable that temporarily connects an appliance to the mains electricity supply via a wall socket or extension cord. The terms are generally used for cables using a power plug to connect to a single-phase alternating current power source at the local line voltage (generally 100 to 240 volts, depending on the location). The terms power cable , mains lead, flex or kettle lead are also used. A lamp cord (also known as a zip cord ) is a light-weight, ungrounded, single-insulated two-wire cord used for small loads such as a table or floor lamp.

Contents

A cord set includes connectors molded to the cord at each end (see Appliance coupler). Cord sets are detachable from both the power supply and the electrical equipment, and consist of a flexible cord with electrical connectors at either end, one male, and one female. One end of the cord set is attached to a molded electrical plug; the other is typically a molded electrical receptacle to prevent the possibility of having an exposed live prong or pin which would cause electric shock. The female connector attaches to the piece of equipment or appliance while the male plug connects to the electrical receptacle or outlet.

Features

Power cables may be either fixed or detachable from the appliance. [1] In the case of detachable leads, the appliance end of the power cord has a female connector to link it to the appliance, to avoid the dangers from having a live protruding pin. Cords may also have twist-locking features, or other attachments to prevent accidental disconnection at one or both ends. A cord set may include accessories such as fuses for overcurrent protection, a pilot lamp to indicate voltage is present, or a leakage current detector. Power cords for sensitive instruments, or audio/video equipment may also include a shield over the power conductors to minimize electromagnetic interference.

A power cord or appliance coupler may have a retaining clamp, a mechanical device that prevents it from inadvertently being pulled or shaken loose. Typical application areas with stricter safety requirements include medical technology, stage and lighting technology, and computing equipment. For specialty equipment such as construction machinery, sound and lighting equipment, emergency medical defibrillators and electrical power tools, used in locations without a convenient power source, extension cords are used to carry the electric current up to hundreds of feet away from an outlet.

In North America, the National Electrical Manufacturers Association develops standards for electrical plugs and receptacles and cables. [2]

International power cords and plug adapters are used in conjunction with electrical appliances in countries different from those in which they were designed to operate. Besides a cord with one end compatible to receptacles or a device from one country and the other end compatible with receptacles or devices from another country, a voltage converter is usually necessary, as well, to protect travelers' electronic devices, such as laptops, from the differing voltages between the United States and places like Europe or Africa.

North American lamp cords have two single-insulated conductors designed for low-current applications. The insulator covering one of the conductors is ribbed (parallel to wire) for the entire length of the cord, while the other conductor's insulator is smooth. The smooth one is hot and the ribbed one is neutral. [3]

Connectors

IEC 60320 power cables come in normal and high-temperature variants, as well as various rated currents. The connectors have slightly different shapes to ensure that it is not possible to substitute a cable with a lower temperature or current rating, but that it is possible to use an overrated cable. Cords also have different types of exterior jackets available to accommodate environmental variables such as moisture, temperature, oils, sunlight, flexibility, and heavy wear. For example, a heating appliance may come with a cord designed to withstand accidental contact with heated surfaces.

Worldwide, more than a dozen different types of AC power plugs and sockets are used for fixed building wiring. Products sold in many different markets can use a standardized IEC 60320 connector and then use a detachable power cord to match the local electrical outlets. This simplifies safety approvals, factory testing, and production since the power cord is a low-cost item available as a commodity. Since the same types of appliance-side connectors are used with both 120 V and 230 V power cables, the user must ensure the connected equipment will operate with the available voltage. Some devices have a slide-switch to adapt to different voltages, or wide-ranging power supplies.

Standards

National electrical codes may apply to power cords and related items. For example, in the United States, power cords must meet UL Standards 62 [4] and 817. [5]

Power supplies

Cord sets must be distinguished from AC adapters, where the connector also contains a transformer, and possibly rectifiers, filters and regulators. Unwary substitution of a standard mains-voltage connector for the power supply would result in application of full line voltage to the connected device, resulting in its destruction and possible fire or personal injury.

See also

Related Research Articles

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<span class="mw-page-title-main">Mains electricity</span> Type of lower-voltage electricity most commonly provided by utilities

Mains electricity or utility power, grid power, domestic power, and wall power, or, in some parts of Canada, hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to homes and businesses through the electrical grid in many parts of the world. People use this electricity to power everyday items by plugging them into a wall outlet.

<span class="mw-page-title-main">IEC 60320</span> Set of standards for AC power connectors used on domestic appliances on the appliance side

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<span class="mw-page-title-main">Power strip</span> Electrical component

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<span class="mw-page-title-main">Gender of connectors and fasteners</span> Male components insert into female components

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In electrical engineering, ground and neutral are circuit conductors used in alternating current (AC) electrical systems. The neutral conductor returns current to the supply. To limit the effects of leakage current from higher-voltage systems, the neutral conductor is often connected to earth ground at the point of supply. A ground conductor is not intended to carry current for normal operation of the circuit, but instead connects exposed metallic components to earth ground. A ground conductor only carries significant current if there is a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. Circuit protection devices may detect a fault to a grounded metal enclosure and automatically de-energize the circuit, or may provide a warning of a ground fault.

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<span class="mw-page-title-main">Extension cord</span>

An extension cord (US), extension cable, power extender, drop cord, or extension lead (UK) is a length of flexible electrical power cable (flex) with a plug on one end and one or more sockets on the other end. The term usually refers to mains extensions but is also used to refer to extensions for other types of cabling. If the plug and power outlet are of different types, the term "adapter cord" may be used. Most extension cords range from around 2 to 30 feet in length although they are made up to 300 feet (91.44 m) in length.

<span class="mw-page-title-main">AS/NZS 3112</span> AC power plug and socket used in Australia and New Zealand

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, New Zealand, Fiji, Tonga, Solomon Islands, Papua New Guinea and several other Pacific island countries, plus in Argentina and China. The International Electrotechnical Commission (IEC) "world plugs" Web site calls this plug Type I.

<span class="mw-page-title-main">NEMA connector</span> Power plugs and receptacles used in North America and some other regions

NEMA connectors are power plugs and sockets used for AC mains electricity in North America and other countries that use the standards set by the US National Electrical Manufacturers Association. NEMA wiring devices are made in current ratings from 15 to 60 amperes (A), with voltage ratings from 125 to 600 volts (V). Different combinations of contact blade widths, shapes, orientations, and dimensions create non-interchangeable connectors that are unique for each combination of voltage, electric current carrying capacity, and grounding system.

<span class="mw-page-title-main">Power entry module</span>

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<span class="mw-page-title-main">Portable appliance testing</span> Procedure in which electrical appliances are routinely checked for safety

In electrical safety testing, portable appliance testing is a process by which electrical appliances are routinely checked for safety, commonly used in the United Kingdom, Ireland, New Zealand and Australia. The formal term for the process is "in-service inspection & testing of electrical equipment". Testing involves a visual inspection of the equipment and verification that power cables are in good condition. Additionally, other tests may be done when required, such as a verification of earthing (grounding) continuity, a test of the soundness of insulation between the current carrying parts, and a check for any exposed metal that could be touched. The formal limits for a pass/fail of these electrical tests vary somewhat depending on the category of equipment being tested.

<span class="mw-page-title-main">AC power plugs and sockets: British and related types</span> AC power plug type

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 official standards arose to enable the interchange of compatible devices. British standards have proliferated throughout large parts of the former British Empire.

There are approximately 20 types in common use around the world, such as AC power plugs and sockets, and many obsolete socket types which are still found in older buildings.

References

  1. Skalak, Richard; Chien, Shu (1987). Handbook of bioengineering. McGraw-Hill. ISBN   9780070577831.
  2. NEMA - Flexible Cords Section Archived 2011-11-03 at the Wayback Machine
  3. Merle Henkenius; Popular Mechanics Dec 1987 How to Repair an Incandescent Lamp:Installing an in-line switch; p.130; (retrieved 3/23/12)
  4. UL 62 (2010-05-18). "Flexible Cords and Cables" . Retrieved 2017-01-25.{{cite web}}: CS1 maint: numeric names: authors list (link)
  5. UL 817 (2001-03-16). "Standard for Cord Sets and Power-Supply Cords" . Retrieved 2017-01-25.{{cite web}}: CS1 maint: numeric names: authors list (link)