Electrical Wiring Safety Standards and Color Coding Quiz

Electrical Wiring: Safety Standards and Color Coding

• Electrical wiring is the installation of cabling and devices such as switches, sockets, and light fittings in a structure.

• Wiring is subject to safety standards for design and installation.

• Allowable wire and cable types and sizes are specified according to the circuit operating voltage and electric current capability.

• Wiring safety codes vary by locality, country, or region.

• Wiring installation codes and regulations are intended to protect people and property from electrical shock and fire hazards.

• In Australia and New Zealand, the AS/NZS 3000 standard specifies requirements for the selection and installation of electrical equipment.

• In European countries, national standards follow an identical system of sections and chapters.

• In the United Kingdom, wiring installations are regulated by the IEE Wiring Regulations, BS 7671: 2008, which are harmonized with IEC 60364.

• In North America, the US National Fire Protection Association has published the National Electrical Code (NEC) since 1897.

• Color coding of wires is mandatory in a typical electrical code.

• In the United States, color-coding of three-phase system conductors follows a de facto standard.

• Materials for wiring interior electrical systems in buildings vary depending on the requirements of the building.Overview of Electrical Wiring: Copper and Aluminum Conductors, Raceways and Cable Runs, Bus Bars, Electrical Panels, and Historical Wiring Methods

• Residential electrical service usually consists of three twisted conductors, with one being a bare neutral conductor and the other two being insulated conductors for both two 180-degree out of phase 120 V line voltages.

• Copper conductors are preferred over aluminum conductors due to their high electrical conductivity, tensile strength, ductility, creep resistance, corrosion resistance, thermal conductivity, and ease of installation.

• Aluminum wire was used in North American residential wiring from the late 1960s to mid-1970s due to the rising cost of copper. However, it requires larger conductors than copper.

• Bus bars are used for high currents distributed through a building, and each live conductor of such a system is a rigid piece of copper or aluminum, usually in flat bars.

• Electrical panels are easily accessible junction boxes used to reroute and switch electrical services, and the term is often used to refer to circuit breaker panels or fuseboxes.

• Squirrels, rats, and other rodents may gnaw on unprotected wiring, causing fire and shock hazards, which is especially true of PVC-insulated telephone and computer network cables.

• The earliest standardized method of wiring in buildings in North America from about 1880 to the 1930s was knob and tube (K&T) wiring.

• Armored cables with two rubber-insulated conductors in a flexible metal sheath were used as early as 1906.

• Rubber-insulated cables become brittle over time due to exposure to atmospheric oxygen, so they must be handled with care and are usually replaced during renovations.

• About 1950, PVC insulation and jackets were introduced, especially for residential wiring.

• The simplest form of cable has two insulated conductors twisted together to form a unit, and such non-jacketed cables with two or more conductors are used only for extra-low voltage signal and control applications such as doorbell wiring.

• Metal moulding systems with a flattened oval section consisting of a base strip and a snap-on cap channel were more costly than open wiring or wooden moulding but could be easily run on wall surfaces.