|Wednesday, 04 October 2006|
Electrical equipment frequently needs to be operated at a distance from an electrical outlet that exceeds the length of the equipment's integral electrical cord. Electrical extension cords are commonly used to supply electrical power to tools and equipment which are remote from electrical outlets and power sources. Electrical extension cords increase the range of the integral electrical cord, typically by connecting the male plug of the integral cord to the female plug of the extension cord and by connecting the male plug of the extension cord to the electrical outlet. They provide a continuous connection between power sources and devices that require electricity to function properly. Extension power cords are essential accessories for residential, industrial, and commercial use of electrical items. They free electrical devices from the requirement of only being operated within a relatively short distance of five or six feet from a power source, like a receptacle. Retractable electrical extension cord allows the cord to be extended only to the degree desired, thereby resulting in a neater appearance, improved safety and protection for the cord not currently used. After use, the cord is then retracted in a convenient manner that protects the cord and enhances appearance. Many power tools require an extension power cord to connect the power tool to an AC power source. Portable AC powered tools such as hedge trimmers or string trimmers typically have male electrical contact blades in the housing of the power tool that connect to a female electrical receptacle plug at the end of an extension power cord.
Power cords are generally small, flexible electrical cables having a plug on at least one end which is used to connect an appliance or electrical tool with a wall outlet or receptacle. These cords include one or more insulated leads which typically project from the end of the cord and extend to various points within the appliance. An extension cord consists of an adapter, into which a plug that is attached to the device can be inserted, and an encased wire that travels from the adapter to the power supply. Each adapter can have either of two basic configurations: metallic prongs that project from a circular face in a perpendicular direction male adapter) or openings that are embedded in the face (female adapter). Electric power cords for household use usually has an insulating coating covering two copper wires to protect the user from an electric shock or prevent a short circuit. Electrical conductors such as cables and electrical cords are typically coated with rubber or plastic. In the basic construction of such cables or wires, the conductor usually is the only metallic part and can be a single or multiple strand surrounded by an enveloping jacket which is usually a unitary plastic composition. Typically, power cord ends comprise male or female plugs which are adapted to cooperate in an interconnected fashion. Typically, the cords comprise a bundle of wires and insulating material (which is often covered by a sheath) with wires being attached to the plug. Tensile forces placed on the electrical cords during their use tend to cause the interconnected plugs to separate.
Electrical power cords, and other forms of electrical connections are usually plugged into some form of receptacle in a wall or other structure. A power cord usually has a male terminal block and a female terminal block and a pliable cord extending therebetween. If the plug of the power cord is imperfectly connected to the inlet of the electrical appliance, or a break occurs as a result of the power cord being pulled or pressed against a wall, the connection between the power cord and the electrical appliance is not kept normal. Various plugs and outlets are provided with connectors for forming a junction and connecting the lead wires provided in the plug's power cord. An electric plug commonly includes a plurality of conductive terminals which are sized and shaped to project into associated receptacles in an electrical outlet. With the electric plug for a power cord inserted into a properly functioning electrical outlet, current travels from the power source, into the outlet, through the plug. Power distribution boxes allow multiple power line cords from multiple devices to be plugged into a single piece of equipment in a convenient manner. A power cord reel is used to hold a power cord, enabling the power cord to be extended to a remote place. When a power cord reel is used, the electric plug of the power cord of the power cord reel is connected to power source, and then the power cord is extended out of the bobbin of the power cord reel, for enabling the power cord reel to be moved to the desired remote plate for the connection of an electric apparatus.
Corded electrical devices or connectors typically include a strain relief assembly for gripping and coupling the power cord and maintaining slack between the ends of the conductors and their respective terminals within the electrical device or connector. The cord and/or insulated leads project through the strain relief and the insulated leads are mechanically attached or soldered to electrical contacts within the electrical appliances. There are a wide variety of strain relief assemblies available for electrical devices or connectors. Many electrical devices or connectors have a pair of cord or cable clamping members for gripping and coupling the electrical cord thereto. Circuit breakers are commonly provided along the current path to protect the load against overcurrent conditions. Surge protector devices, variously known as voltage spike protectors or voltage surge suppressors, provide electronic circuitry to protect sensitive electronic equipment from high energy transient disturbances that may occur on an AC power line. The power cord lock is used to inhibit the unauthorized use of electrical or electronic equipment by precluding the plug end of the equipment power cord from being inserted into an electrical outlet, thereby eliminating power to the equipment and rendering the equipment inoperative. Typically a power cord has a covering to protect the cord or cable against the accumulation of moisture and against corrosion.