An extension cord , power extender , drop cable , or lead extension is the length of a flexible power cord (flex ) with a plug on one end and one or more sockets at the other end (usually with the same type as the plug). This term usually refers to the main extension (domestic air conditioner) but is also used to refer to extensions for other cable types. If the plug and socket have a different type, the term "adapter cable" can be used. Most extension cables range from about two to thirty feet in length even though they are made up to 300 feet in length.
Video Extension cord
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The term "extension cable" has been in use since at least 1925.
Extension cables come in different colors, lengths, thicknesses and service tasks. In general, the more power required by the tool, the thicker the cable needs (meaning larger cables inside). Cables to be used outdoors, in wet areas, around oils, or exposed to sun for a long period of time should be selected for those specific conditions. The extension roll is a rolling extension, usually to the end of the socket, which in some cases has more than one socket (often 2 or 4). Another type of rolling extension is hanging near the end of the plug and allows the user to pull the cable out by grasping the end of the socket.
Some extension cables also incorporate safety features such as polarized plugs and electrical outlets, ground terminals, "power-on" indicators, melt-out links, or even current-loss devices (also known as ground-fault circuit interfaces or GFCI).
Some cables contain several female connectors that are adjacent to one another; others have female connectors that are spaced along the cord. The cables generally contain earthed or non-ungrounded connectors. While a diode male connector can be forced into an unsigned female socket, it is not safe.
Variations
The power strip is a block on the end of the power cord with a number of sockets (usually 3 or more), often arranged in a row. The term is also used to refer to all short extension cable units ending in the power strip.
The removable power cable is similar but much shorter, and is designed to connect the appliance to an electrical outlet. Couple of ladies with entry tool.
Maps Extension cord
Rule
The National Electrical Code (USA)
In the United States the domestic voltage is 120 V, and the National Electric Code (NEC) prohibits the use of extension cables in circuit 20 A unless they have 16 AWG or larger diameter (for example, 14 AWG or 12 AWG).
Like other flexible cables, NEC also prohibits its use when attached to a building's surface, hiding inner structures (walls, floors, ceilings), above suspended ceilings, or through holes or other holes (windows, doors) in the structure. NEC does contain exceptions though very limited.
In the United States, Underwriters Laboratories declares that cable extension is in accordance with NEC. The main standards are UL 817 for all extension cords, and UL 62 for the electrical wiring itself. The US Public Service Administration also maintains the standard for extension cords, J-C-1270, which references the UL standard and provides additional criteria.
NEC tries to reduce the potential fire hazard by requiring that there is a container within 6 feet (1.8 m) of any point along the wall in the dwelling, reducing the need for extension cords. However, even at home with more containers than the Code requires, there will sometimes be a need for extension cords.
Europe
In Europe and elsewhere where normal domestic stresses are around 230 V there may be less risk of causing fires through overheating of wires for given power due to lower currents. But most of the European cable extension cables now include automatic cut-out flows to avoid wiring misuse. This requires manual resetting if the overcurrent is pulled through the cable. (American multi-plug cables also include such devices, but a single or triple-stop channel cable does not.)
Dangers
Historical studies of fire incidents have shown that most structural fires are caused by extension cords that have been damaged or overloaded.
Extension cable insulation, especially a two-wire, light-duty cable, is easily damaged by being pinched, crushed, or peeling. Cables can also be damaged at plug connections and sockets with excessive drawn, which sometimes happens when people pass through. Overloading can cause extension cords to heat up to the point where the insulation is melted or carbonized. Heating equipment can also cause heat damage to cable insulation, melt, or burn it.
If the internal metal wires are damaged, as with the wires being smashed in the door, then where the unbroken part of the cable is narrower than most of the wires, this can form a high resistance point. A hot spot may develop because the resistance of the narrower wire portion is higher than that of the other wire, and thus tends to concentrate the power of dissipation there.
Animals can chew the cable and remove some insulation. In these cases if the damage is not addressed and the cord is not repaired or taken out of service, the damage may cause a short arch or circuit between the wires, which can ignite nearby material. Open wires from extension cords with damaged insulation can also present a shock hazard to humans and animals.
Security
Wires running across the floor must be sealed with the appropriate device to protect it from physical damage. However, they should not be covered with carpet or carpet, as this can result in serious fire hazards.
To avoid the need for long roll over, using roll extension or to cut the cable to size, extension cords are sold in prefabricated lengths from 1 to 150 feet (30 cm to 45 m). Each umbilical cord increases the electrical resistance, which in turn lowers the power the cable can provide. Therefore, the longer the cable, the larger the conductor diameter necessary to minimize the voltage drop (the smaller wire gauge number for larger diameter wire). Because of this, it is best to use the exact cable as long as it is needed and nothing more.
The extension rolls can only carry a full measured current when completely extended. This is because the wires on the reel are not exposed to air causing the loss of power, (the result of series resistance), does not disappear. Extension cords used when rolled or rolled in rolls can be a serious shock and a fire hazard. The heat generated from the resistance can not disappear and is even trapped between the rolled wires, which lead to fire or shock. In addition, ESFI recommends never to use additional cables covered by carpets or blankets, or run through ceilings or walls, as heat may not be able to disappear properly.
Primary content
Extension cables sold in the United States may contain lead in a PVC insulation sheath. California Proposition 65 (1986) requires manufacturers to warn consumers when products contain toxic chemicals. Many extension cables carry warning labels that advise consumers to wash their hands after handling them.
The European Directive, RoHS, limits the use of hazardous materials such as lead in the manufacture of electrical products such as extension cables. Some manufacturers have moved to RoHS compliance but currently there is no widespread movement in the US to stop manufacturing lead-filled products.
Maintenance
The attention required to safely use extension cords includes extension cords away from where they are likely to be damaged, using the shortest cable that will serve each intended purpose, and check the cables periodically for damage or signs of overloading (melting deformation, embezzlement in color, or "burn" or "electric" smell).
Periodic inspections are essential for long-lasting straps, for example behind furniture, where damage may be missed and by accidental coincidental conditions for fire or electric shock incidents occur (for example, some dust or paper falls close arc wire, or liquid spills occur and flows into the open wire).
Another dangerous modification to the extension cord is to remove the third branch to fit the socket, resulting in the earthing tree deletion, as well as the loss of hot/neutral branches.
signal cable extension
Extension cords sometimes refer to cables that increase the length of the signal transmission cable or a combination of signal/power cables (for example, a USB cable). They are more likely to be called "extender" or "extender cable" or "cable extender". The extenders have one male and one female connector.
The passive USB extension cable does not meet the USB standard and is therefore prohibited to carry the USB logo. The only cable structure recognized by the official USB standard is one with plugs A and plug B (either regular or mini-B) at both ends. This restriction is intended to prevent cable length greater than the maximum permitted by the USB standard so as not to be assembled and to avoid the accumulation of resistance in the connection beyond the design limit of USB, to ensure consistent plug and play operation of the USB System without the need for the user to calculate the cable length or enforce technical rules.
The purpose of USB is to make sure that any standard compliant cable can be used to connect two compatible devices, and the connection will work, without question. For this purpose, the USB standard limits the maximum length of a compatible USB cable (and thus logo) (up to about 15 feet), and up to this length, the user is expected to purchase a cable longer than extending the shorter cable. they already have. For longer cables, a USB hub is required. However, if one chooses to eliminate the aspect "requires no technical knowledge required" and thinks as an engineer, it is possible to use a passive USB extension cable to assemble cables that are close to 15 feet and use them without problems. Although not standard, this extender cable is readily available from many sources.
Another class of USB extensions is actually a USB hub with a fixed cable length permanently installed. This conforms to the USB standard, if not more than the limited number connected together. However, they require power from a USB connection and so can reduce the power available to the device at the "B" end.
See also
- IEC 60320
- MCX connector (antenna)
- Portable cable
References
External links
- Extension Cables at Underwriters Laboratories Inc
- Solution for lack of sockets? BBC News article
Source of the article : Wikipedia
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