The anatomy of wire includes the:
1. - A material, usually a metal such as copper, which allows electrical current to pass from a source to its load. The diameter of a conductor determines the amount of current it can carry. The larger the conductor, the more current. While copper is usually the conductor of choice, other metals including aluminum, gold, steel and brass are also conductors. (Click to learn why copper is the conductor of choice.)
2. - Insulation provides physical and electrical separation of conductors and minimizes the free flow of electrical charge from the conductor. It guards against interference and maximizes electrical signal strength, and as such, always consists of non-conductive material to resist the flow of electricity. While insulators can be solid, liquid, or gas, we’ll concentrate on solids.
- Plastics: Plastic insulators come in a wide range of options from polyvinylchloride (PVC) to polyurethane and polyethylene. These insulators come in a wide variety of thicknesses and rigidities and can be used in many different applications and environments.
- Fluoropolymers: These insulators are great for high-temperature applications because of its superb electrical properties like high dielectric strength, low dielectric loss and low dielectric constant.
- Rubber: Rubber insulation like ethylene propylene, silicone and neoprene are popular choices due to their long life, flexibility and ability to withstand high temperatures.
3. – Any current-carrying conductor, including wire and cable, radiates an electromagnetic field. Some wires and cables include shielding to reduce electrical noise and electromagnetic radiation that may interfere with current or signal transmission. A shield is a layer of aluminum foil or woven mesh braid that surrounds the insulation. Foil provides complete coverage of the conductors while braided shields provide 70-95% coverage, which is sufficient for most applications.
4. – The jacket protects the internal components of a wire; provides differentiation in its physical appearance; and provides flame, mechanical, thermal, chemical and environmental protection to the conductors and components. The two leading types of jackets are thermoplastic and thermoset. The former is more common, while the latter is generally used in specialty applications.
- (commonly made of PVC, polyethylene, polyurethane, polypropylene) is light weight, easily colored, and usually cost-effective. It will melt at high temperature. (Think “plastic.”)
- (commonly made of rubber, neoprene, silicone) is useful in extreme environments; unlike thermoplastic compound, will not re-melt after extrusion. (Think “set.”)
5. – A wire that is wrapped around or part of a shield within a cable that reduces the resistance from any point on the shield to ground. A drain wire serves to complete an electrical circuit from the shield, thereby carrying extraneous electrical noise to ground and away from the circuit or system the shield is intended to protect.