An extension cord is a type of electrical wiring used to extend the length of a power cord. A standard extension cord consists of one or more metal wires protected by a plastic or PVC insulation coating. One end of the cord features an input plug for electrical devices, while the other features a pronged-plug that can be inserted into a wall outlet. These cords allow users to power objects located far from an electrical outlet, or even objects located outdoors.
Extension cords come in many lengths and sizes to suit the needs of different users. Generally, buyers choose a short cord for convenience and ease of use on small jobs, while long cords may be needed for projects located far from a power outlet. Contractors and others who use an extension cord frequently may purchase several cords in varying lengths to accommodate different types of projects. Thicker cords typically contain thicker wires, leaving them capable of transferring higher electrical loads. Thinner cords, on the other hand, contain fewer wires, and are designed to handle lighter power loads.
Each extension cord is designed specifically for use indoors or out. A cord rated for outdoor use can safely be used indoors, but an indoor cord should never be used outside. Cords with an industrial rating are designed to withstand use around oil, chemicals, or other materials likely to cause corrosion.
Before choosing an extension cord, buyers should check the electrical plug to determine which cords will work with different types of appliances. Some basic lighting and appliances utilize a two-prong outlet, while microwaves and other large appliances require a three-prong outlet. This third prong acts to ground the cord, so cords with missing grounding prongs should not be used. Some specialty applications may even require an extension cord with a twist-lock connector, or other specialized prong design.
In addition to basic extension cord designs, some cords include special features that add convenience and versatility. While most cords power only a single appliance, some contain a special power strip that can be used to power two or more fixtures. This power strip often comes with its own on-off switch to help save power when the appliances are not in use.
Wireless extension cords offer a convenient alternative to traditional cords. To operate these units, users plug the base of the cord into any wall outlet. The base transmits power to a receiver unit using microwaves or radio waves. Users can then plug items into the receiver to power them without the use of wires.