Power cord

For a musical interval played on an electric guitar, see Power chord.

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.^[1] 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.

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 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 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.

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. 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 supplies, 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

Energy portal

• Chart of plugs for each country
• Extension cord, extension lead
• Power strip
• Power supply

References

1. ^ NEMA - Flexible Cords Section