Power cord
Encyclopedia
A power cord, line cord, or mains cable is a 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 is a light weight ungrounded two wire cord used for small loads such as a table or floor lamp. The term cord set is also used to distinguish those cords that include connectors molded to the cord at each end.
Cord sets, like power cords, or extension cords, are a means of connecting a main power supply to a piece of electrical equipment or appliance. 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 plug is connected to the piece of equipment or appliance while the male plug connects to the electrical receptacle or outlet.
In North America, NEMA power cords (National Electrical Manufacturers Association) are the standard for electrical plugs, cord voltage capabilities and receptacle configuration. 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. Cord sets are used in any application which requires the existence of electrical energy to operate, such as office space, industrial operations, medical machinery, commercial appliances, etc. 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 electrical current up to hundreds of feet away from an outlet.
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 may have a retaining clamp, a mechanical device that prevents an appliance coupler from inadvertently being pulled or shaken loose. Typical application areas with stricter safety requirements include medical technology
, stage and lighting technology as well as IT.
Worldwide, more than a dozen different types of connectors 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. Note that the same types of appliance-side connectors are used with both 110 V and 230 V power cables, so care must be used when moving appliances between countries with different voltage standards — substituting a power cord that matches local power outlets will result in an incorrect voltage being applied to the appliance or equipment. Some devices have a slide-switch to adapt to different voltages, or wide-ranging power supplies. Unless explicitly labelled as capable of handling local voltages, this is very likely to damage or destroy the appliance.
, 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.
Cable
A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...
that temporarily connects an appliance to the mains electricity
Mains electricity
Mains is the general-purpose alternating current electric power supply. In the US, electric power is referred to by several names including household power, household electricity, powerline, domestic power, wall power, line power, AC power, city power, street power, and grid power...
supply via a wall socket or extension cord
Extension cord
An extension cord, power extender, or extension lead is a length of flexible electrical power cable 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...
. The terms are generally used for cables using a power plug to connect to a single-phase alternating current
Alternating current
In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....
power source at the local line voltage—(generally 100 to 240 volts, depending on the location). The terms power cable
Power cable
A power cable is an assembly of two or more electrical conductors, usually held together with an overall sheath. The assembly is used for transmission of electrical power...
, mains lead, flex or kettle lead are also used. A lamp cord is a light weight ungrounded two wire cord used for small loads such as a table or floor lamp. The term cord set is also used to distinguish those cords that include connectors molded to the cord at each end.
Cord sets, like power cords, or extension cords, are a means of connecting a main power supply to a piece of electrical equipment or appliance. 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 plug is connected to the piece of equipment or appliance while the male plug connects to the electrical receptacle or outlet.
In North America, NEMA power cords (National Electrical Manufacturers Association) are the standard for electrical plugs, cord voltage capabilities and receptacle configuration. 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
Voltage converter
A voltage converter changes the voltage of an electrical power source. It may be combined with other components to create a power supply.-AC and DC:...
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. Cord sets are used in any application which requires the existence of electrical energy to operate, such as office space, industrial operations, medical machinery, commercial appliances, etc. 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 electrical current up to hundreds of feet away from an outlet.
Features
Power cables may be either fixed or detachable from the appliance. In the case of detachable leads, the appliance end of the power cord has a socket rather than a plug 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 fusesFuse (electrical)
In electronics and electrical engineering, a fuse is a type of low resistance resistor that acts as a sacrificial device to provide overcurrent protection, of either the load or source circuit...
for overcurrent protection, a pilot lamp to indicate voltage is present, or a leakage current detector
Residual-current device
A Residual Current Device is a generic term covering both RCCBs and RCBOs.A Residual-Current Circuit Breaker is an electrical wiring device that disconnects a circuit whenever it detects that the electric current is not balanced between the energized conductor and the return neutral conductor...
. Power cords for sensitive instruments, or audio/video equipment may also include a shield
Shielded cable
A shielded or screened cable is an electrical cable of one or more insulated conductors enclosed by a common conductive layer. The shield may be composed of braided strands of copper , a non-braided spiral winding of copper tape, or a layer of conducting polymer. Usually, this shield is covered...
over the power conductors to minimize electromagnetic interference
Electromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
.
A power cord may have a retaining clamp, a mechanical device that prevents an appliance coupler from inadvertently being pulled or shaken loose. Typical application areas with stricter safety requirements include medical technology
Medical technology
Medical Technology encompasses a wide range of healthcare products and is used to diagnose, monitor or treat diseases or medical conditions affecting humans. Such technologies are intended to improve the quality of healthcare delivered through earlier diagnosis, less invasive treatment options and...
, stage and lighting technology as well as IT.
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 over-rated 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 connectors are used for fixed building wiring
Electrical wiring
Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. This article describes general aspects of electrical wiring as used to provide power in buildings and structures, commonly referred to as building wiring. This article is intended to...
. 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. Note that the same types of appliance-side connectors are used with both 110 V and 230 V power cables, so care must be used when moving appliances between countries with different voltage standards — substituting a power cord that matches local power outlets will result in an incorrect voltage being applied to the appliance or equipment. Some devices have a slide-switch to adapt to different voltages, or wide-ranging power supplies. Unless explicitly labelled as capable of handling local voltages, this is very likely to damage or destroy the appliance.
Power supplies
Cord sets must be distinguished from plug-in wall mounted power suppliesWall wart
The AC adapter, AC/DC adapter or AC/DC converter is a type of external power supply, often enclosed in what looks like an over-sized AC plug. Other names include plug pack, plug-in adapter, adapter block, domestic mains adapter, line power adapter, or power adapter...
, where the connector also contains a transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
, 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
- Chart of plugs for each country
- Extension cord, extension lead
- Power stripPower stripA power strip is a block of electrical sockets that attaches to the end of a flexible cable and allows multiple electrical devices to be plugged in. As such it can be considered a type of trailing socket though that term is more often used for single and double cable mounted sockets...
- Power supplyPower supplyA power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy to electrical energy...