Electrical wiring is an electrical installation of cabling and associated devices such as switches, distribution boards, 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, with further restrictions on the environmental conditions, such as ambient temperature range, moisture levels, and exposure to sunlight and chemicals.
Associated circuit protection, control and distribution devices within a building's wiring system are subject to voltage, current and functional specification. Wiring safety codes vary by locality, country or region. The International Electrotechnical Commission (IEC) is attempting to harmonise wiring standards amongst member countries, but significant variations in design and installation requirements still exist.
Wiring installation codes and regulations are intended to protect people and property from electrical shock and fire hazards. They are usually based on a model code (with or without local amendments) produced by a national or international standards organisation, such as the IEC.
In Australia and New Zealand, the AS/NZS 3000 standard, commonly known as the "wiring rules", specifies requirements for the selection and installation of electrical equipment, and the design and testing of such installations. The standard is mandatory in both New Zealand and Australia; therefore, all electrical work covered by the standard must comply.
In European countries, an attempt has been made to harmonise national wiring standards in an IEC standard, IEC 60364 Electrical Installations for Buildings. Hence national standards follow an identical system of sections and chapters. However, this standard is not written in such language that it can readily be adopted as a national wiring code. Neither is it designed for field use by electrical tradesmen and inspectors for testing compliance with national wiring standards. By contrast, national codes, such as the NEC or CSA C22.1, generally exemplify the common objectives of IEC 60364, but provide specific rules in a form that allows for guidance of those installing and inspecting electrical systems.
In Germany, DKE (the German Commission for Electrical, Electronic and Information Technologies of DIN and VDE) is the organisation responsible for the promulgation of electrical standards and safety specifications. DIN VDE 0100 is the German wiring regulations document harmonised with IEC 60364.
The first electrical codes in the United States originated in New York in 1881 to regulate installations of electric lighting. Since 1897 the US National Fire Protection Association, a private non-profit association formed by insurance companies, has published the National Electrical Code (NEC). States, counties or cities often include the NEC in their local building codes by reference along with local differences. The NEC is modified every three years. It is a consensus code considering suggestions from interested parties. The proposals are studied by committees of engineers, tradesmen, manufacturer representatives, fire fighters and other invitees.
Since 1927, the Canadian Standards Association (CSA) has produced the Canadian Safety Standard for Electrical Installations, which is the basis for provincial electrical codes. The CSA also produces the Canadian Electrical Code, the 2006 edition of which references IEC 60364 (Electrical Installations for Buildings) and states that the code addresses the fundamental principles of electrical protection in Section 131. The Canadian code reprints Chapter 13 of IEC 60364, but there are no numerical criteria listed in that chapter to assess the adequacy of any electrical installation.
Although the US and Canadian national standards deal with the same physical phenomena and broadly similar objectives, they differ occasionally in technical detail. As part of the North American Free Trade Agreement (NAFTA) program, US and Canadian standards are slowly converging toward each other, in a process known as harmonisation.
In the United Kingdom, wiring installations are regulated by the Institution of Engineering and Technology Requirements for Electrical Installations: IEE Wiring Regulations, BS 7671: 2008, which are harmonised with IEC 60364. The 17th edition (issued in January 2008) includes new sections for microgeneration and solar photovoltaic systems. The first edition was published in 1882. In 2018 the 18th edition of the wiring regulations BS7671:2018 was released and came into force in January 2019.
In a typical electrical code, some colour-coding of wires is mandatory. Many local rules and exceptions exist per country, state or region. Older installations vary in colour codes, and colours may fade with insulation exposure to heat, light and ageing.
As of March 2011, the European Committee for Electrotechnical Standardization (CENELEC) requires the use of green/yellow colour cables as protective conductors, blue as neutral conductors and brown as single-phase conductors.
The United States National Electrical Code requires a bare copper, or green or green/yellow insulated protective conductor, a white or grey neutral, with any other colour used for single phase. The NEC also requires the "high leg" conductor of a High-leg delta or "bastard-leg" system to have orange insulation.
The introduction of the NEC clearly states that it is not intended to be a design manual, and therefore, creating a colour code for ungrounded or "hot" conductors falls outside the scope and purpose of the NEC. However, it is a common misconception that "hot" conductor colour-coding is required by the Code.
In the United States, colour-coding of three-phase system conductors follows a de facto standard, wherein black, red, and blue are used for three-phase 120/208-volt systems, and brown, orange, and yellow are used in 277/480-volt systems. In buildings with multiple voltage systems, the grounded conductors (neutrals) of both systems are required to be identified and made distinguishable to avoid cross-system connections. Most often, 120/208-volt systems use white insulation, while 277/480-volt systems use grey insulation, although this particular colour code is not currently an explicit requirement of the NEC.
The United Kingdom requires the use of wire covered with green/yellow striped insulation, for safety earthing (grounding) connections. This growing international standard was adopted for its distinctive appearance, to reduce the likelihood of dangerous confusion of safety earthing (grounding) wires with other electrical functions, especially by persons affected by red-green colour blindness.
In the UK, phases could be identified as being live by using coloured indicator lights: red, yellow and blue. The new cable colours of brown, black and grey do not lend themselves to coloured indicators. For this reason, three-phase control panels will often use indicator lights of the old colours.
|Flexible cable (e.g., extension, power, and lamp cords)|
|Region or country||Phases||Neutral||Protective earth/ground|
|Argentina, European Union, South Africa (IEC 60446)|
|Australia, New Zealand (AS/NZS 3000:2007 3.8.1, 3.8.3)||, (previously), "any colour other than green, yellow, green/yellow, black or light blue"||, (previously)||,|
, green/yellow striped
|United States, Canada (120 V)||
|, ; |
, green/yellow striped
|United States, Canada (240 V)||Line 1, Line 2||
(Needed only if 120 V also is required.)
|, ; |
, green/yellow striped
|Fixed cable (e.g., in-, on-, or behind-the-wall cables)|
|Region or country||Phases||Neutral||Protective earth/ground|
|Argentina; China; European Union (IEC 60446) from April 2004; the United Kingdom from 31 March 2004 (BS 7671); Hong Kong from July 2007; Singapore from March 2009; Russia since 2009 (GOST R 50462); Ukraine, Belarus, Kazakhstan||, ,||[b]|
|India, Pakistan; United Kingdom, prior to 31 March 2004 (BS 7671); Hong Kong, prior to 2009; Malaysia and Singapore, prior to February 2011||, ,|
|Australia, New Zealand (AS/NZS 3000:2018 3.8.1, table 3.4)||
||[c]|| (since about 1980 - Stranded Wire)|
(since about 1966 - Stranded Wire)
Stranded Wire - no insulation; sleeved at the ends (previously)[d]
|Brazil||, , ,|
|United States[e]||, , for 120, 208, or 240 V
, , for 277, or 480 V
| for 120, 208, or 240 V
for 277, or 480 V
required for isolated systems
|Canada[e]||, for single-phase systems
, , for three-phase systems
|, for isolated single-phase systems
, , for isolated three-phase systems
|, for isolated systems|
|Boxes (e.g., translucent purple) denote markings on wiring terminals.
Materials for wiring interior electrical systems in buildings vary depending on:
Wiring systems in a single family home or duplex, for example, are simple, with relatively low power requirements, infrequent changes to the building structure and layout, usually with dry, moderate temperature and non-corrosive environmental conditions. In a light commercial environment, more frequent wiring changes can be expected, large apparatus may be installed and special conditions of heat or moisture may apply. Heavy industries have more demanding wiring requirements, such as very large currents and higher voltages, frequent changes of equipment layout, corrosive, or wet or explosive atmospheres. In facilities that handle flammable gases or liquids, special rules may govern the installation and wiring of electrical equipment in hazardous areas.
Wires and cables are rated by the circuit voltage, temperature rating and environmental conditions (moisture, sunlight, oil, chemicals) in which they can be used. A wire or cable has a voltage (to neutral) rating and a maximum conductor surface temperature rating. The amount of current a cable or wire can safely carry depends on the installation conditions.
Modern non-metallic sheathed cables, such as (US and Canadian) Types NMB and NMC, consist of two to four wires covered with thermoplastic insulation, plus a bare wire for grounding (bonding), surrounded by a flexible plastic jacket. Some versions wrap the individual conductors in paper before the plastic jacket is applied.
Special versions of non-metallic sheathed cables, such as US Type UF, are designed for direct underground burial (often with separate mechanical protection) or exterior use where exposure to ultraviolet radiation (UV) is a possibility. These cables differ in having a moisture-resistant construction, lacking paper or other absorbent fillers, and being formulated for UV resistance.
Rubber-like synthetic polymer insulation is used in industrial cables and power cables installed underground because of its superior moisture resistance.
Insulated cables are rated by their allowable operating voltage and their maximum operating temperature at the conductor surface. A cable may carry multiple usage ratings for applications, for example, one rating for dry installations and another when exposed to moisture or oil.
Generally, single conductor building wire in small sizes is solid wire, since the wiring is not required to be very flexible. Building wire conductors larger than 10 AWG (or about 6 mm²) are stranded for flexibility during installation, but are not sufficiently pliable to use as appliance cord.
Cables for industrial, commercial and apartment buildings may contain many insulated conductors in an overall jacket, with helical tape steel or aluminium armour, or steel wire armour, and perhaps as well an overall PVC or lead jacket for protection from moisture and physical damage. Cables intended for very flexible service or in marine applications may be protected by woven bronze wires. Power or communications cables (e.g., computer networking) that are routed in or through air-handling spaces (plenums) of office buildings are required under the model building code to be either encased in metal conduit, or rated for low flame and smoke production.
For some industrial uses in steel mills and similar hot environments, no organic material gives satisfactory service. Cables insulated with compressed mica flakes are sometimes used. Another form of high-temperature cable is a mineral insulated cable, with individual conductors placed within a copper tube and the space filled with magnesium oxide powder. The whole assembly is drawn down to smaller sizes, thereby compressing the powder. Such cables have a certified fire resistance rating and are more costly than non-fire rated cable. They have little flexibility and behave more like rigid conduit rather than flexible cables.
The environment of the installed wires determine how much current a cable is permitted to carry. Because multiple conductors bundled in a cable cannot dissipate heat as easily as single insulated conductors, those circuits are always rated at a lower "ampacity". Tables in electrical safety codes give the maximum allowable current based on size of conductor, voltage potential, insulation type and thickness, and the temperature rating of the cable itself. The allowable current will also be different for wet or dry locations, for hot (attic) or cool (underground) locations. In a run of cable through several areas, the part with the lowest rating becomes the rating of the overall run.
Cables usually are secured with special fittings where they enter electrical apparatus; this may be a simple screw clamp for jacketed cables in a dry location, or a polymer-gasketed cable connector that mechanically engages the armour of an armoured cable and provides a water-resistant connection. Special cable fittings may be applied to prevent explosive gases from flowing in the interior of jacketed cables, where the cable passes through areas where flammable gases are present. To prevent loosening of the connections of individual conductors of a cable, cables must be supported near their entrance to devices and at regular intervals along their runs. In tall buildings, special designs are required to support the conductors of vertical runs of cable. Generally, only one cable per fitting is permitted, unless the fitting is rated or listed for multiple cables.
Special cable constructions and termination techniques are required for cables installed in ships. Such assemblies are subjected to environmental and mechanical extremes. Therefore, in addition to electrical and fire safety concerns, such cables may also be required to be pressure-resistant where they penetrate a vessel's bulkheads. They must also resist corrosion caused by salt water or salt spray, which is accomplished through the use of thicker, specially constructed jackets, and by tinning the individual wire stands.
In North American practice, an overhead cable from a transformer on a power pole to a residential electrical service usually consists of three twisted (triplexed) conductors, with one being a bare neutral conductor, with the other two being the insulated conductors for both of the two 180 degree out of phase 120 V line voltages normally supplied. The neutral conductor is often a supporting "messenger" steel wire, which is used to support the insulated Line conductors.
Electrical devices often contain copper conductors because of their multiple beneficial properties, including their high electrical conductivity, tensile strength, ductility, creep resistance, corrosion resistance, thermal conductivity, coefficient of thermal expansion, solderability, resistance to electrical overloads, compatibility with electrical insulators and ease of installation.
Despite competition from other materials, copper remains the preferred electrical conductor in nearly all categories of electrical wiring. For example, copper is used to conduct electricity in high, medium and low voltage power networks, including power generation, power transmission, power distribution, telecommunications, electronics circuitry, data processing, instrumentation, appliances, entertainment systems, motors, transformers, heavy industrial machinery and countless other types of electrical equipment.
Aluminium wire was common in North American residential wiring from the late 1960s to mid-1970s due to the rising cost of copper. Because of its greater resistivity, aluminium wiring requires larger conductors than copper. For instance, instead of 14 AWG (American wire gauge) copper wire, aluminium wiring would need to be 12 AWG on a typical 15 ampere lighting circuit, though local building codes vary.
Solid aluminium conductors were originally made in the 1960s from a utility grade aluminium alloy that had undesirable properties for a building wire, and were used with wiring devices intended for copper conductors. These practices were found to cause defective connections and potential fire hazards. In the early 1970s new aluminium wire made from one of several special alloys was introduced, and all devices — breakers, switches, receptacles, splice connectors, wire nuts, etc. — were specially designed for the purpose. These newer aluminium wires and special designs address problems with junctions between dissimilar metals, oxidation on metal surfaces and mechanical effects that occur as different metals expand at different rates with increases in temperature.
Unlike copper, aluminium has a tendency to creep or cold-flow under pressure, so older plain steel screw clamped connections could become loose over time. Newer electrical devices designed for aluminium conductors have features intended to compensate for this effect. Unlike copper, aluminium forms an insulating oxide layer on the surface. This is sometimes addressed by coating aluminium conductors with an antioxidant paste (containing zinc dust in a low-residue polybutene base) at joints, or by applying a mechanical termination designed to break through the oxide layer during installation.
Some terminations on wiring devices designed only for copper wire would overheat under heavy current load and cause fires when used with aluminium conductors. Revised standards for wire materials and wiring devices (such as the CO/ALR "copper-aluminium-revised" designation) were developed to reduce these problems. While larger sizes are still used to feed power to electrical panels and large devices, aluminium wiring for residential use has acquired a poor reputation and has fallen out of favour.
Aluminium conductors are still heavily used for bulk power distribution and large feeder circuits with heavy current loads, due to the various advantages they offer over copper wiring. Aluminium conductors both cost and weigh less than copper conductors, so a much larger cross sectional area can be used for the same weight and price. This can compensate for the higher resistance and lower mechanical strength of aluminium, meaning the larger cross sectional area is needed to achieve comparable current capacity and other features. Aluminium conductors must be installed with compatible connectors and special care must be taken to ensure the contact surface does not oxidise.
Insulated wires may be run in one of several forms between electrical devices. This may be a specialised bendable pipe, called a conduit, or one of several varieties of metal (rigid steel or aluminium) or non-metallic (PVC or HDPE) tubing. Rectangular cross-section metal or PVC wire troughs (North America) or trunking (UK) may be used if many circuits are required. Wires run underground may be run in plastic tubing encased in concrete, but metal elbows may be used in severe pulls. Wiring in exposed areas, for example factory floors, may be run in cable trays or rectangular raceways having lids.
Where wiring, or raceways that hold the wiring, must traverse fire-resistance rated walls and floors, the openings are required by local building codes to be firestopped. In cases where safety-critical wiring must be kept operational during an accidental fire, fireproofing must be applied to maintain circuit integrity in a manner to comply with a product's certification listing. The nature and thickness of any passive fire protection materials used in conjunction with wiring and raceways has a quantifiable impact upon the ampacity derating, because the thermal insulation properties needed for fire resistance also inhibit air cooling of power conductors.
Cable trays are used in industrial areas where many insulated cables are run together. Individual cables can exit the tray at any point, simplifying the wiring installation and reducing the labour cost for installing new cables. Power cables may have fittings in the tray to maintain clearance between the conductors, but small control wiring is often installed without any intentional spacing between cables.
Local electrical regulations may restrict or place special requirements on mixing of voltage levels within one cable tray. Good design practices may segregate, for example, low level measurement or signal cables from trays carrying high power branch circuits, to prevent induction of noise into sensitive circuits.
Since wires run in conduits or underground cannot dissipate heat as easily as in open air, and since adjacent circuits contribute induced currents, wiring regulations give rules to establish the current capacity (ampacity).
Special sealed fittings are used for wiring routed through potentially explosive atmospheres.
For very high currents in electrical apparatus, and for high currents distributed through a building, bus bars can be used. (The term "bus" is a contraction of the Latin omnibus – meaning "for all".) Each live conductor of such a system is a rigid piece of copper or aluminium, usually in flat bars (but sometimes as tubing or other shapes). Open bus bars are never used in publicly accessible areas, although they are used in manufacturing plants and power company switch yards to gain the benefit of air cooling. A variation is to use heavy cables, especially where it is desirable to transpose or "roll" phases.
In industrial applications, conductor bars are often pre-assembled with insulators in grounded enclosures. This assembly, known as bus duct or busway, can be used for connections to large switchgear or for bringing the main power feed into a building. A form of bus duct known as "plug-in bus" is used to distribute power down the length of a building; it is constructed to allow tap-off switches or motor controllers to be installed at designated places along the bus. The big advantage of this scheme is the ability to remove or add a branch circuit without removing voltage from the whole duct.
Bus ducts may have all phase conductors in the same enclosure (non-isolated bus), or may have each conductor separated by a grounded barrier from the adjacent phases (segregated bus). For conducting large currents between devices, a cable bus is used.
For very large currents in generating stations or substations, where it is difficult to provide circuit protection, an isolated-phase bus is used. Each phase of the circuit is run in a separate grounded metal enclosure. The only fault possible is a phase-to-ground fault, since the enclosures are separated. This type of bus can be rated up to 50,000 amperes and up to hundreds of kilovolts (during normal service, not just for faults), but is not used for building wiring in the conventional sense.
Electrical panels are easily accessible junction boxes used to reroute and switch electrical services. The term is often used to refer to circuit breaker panels or fuseboxes. Local codes can specify physical clearance around the panels.
Squirrels, rats and other rodents may gnaw on unprotected wiring, causing fire and shock hazards. This is especially true of PVC-insulated telephone and computer network cables. Several techniques have been developed to deter these pests, including insulation loaded with pepper dust.
The first interior power wiring systems used conductors that were bare or covered with cloth, which were secured by staples to the framing of the building or on running boards. Where conductors went through walls, they were protected with cloth tape. Splices were done similarly to telegraph connections, and soldered for security. Underground conductors were insulated with wrappings of cloth tape soaked in pitch, and laid in wooden troughs which were then buried. Such wiring systems were unsatisfactory because of the danger of electrocution and fire, plus the high labour cost for such installations. The first Electrical codes arose in the 1880s with the commercial introduction of electrical power, however, many conflicting standards existed for the selection of wire sizes and other design rules for electrical installations, and a need was seen to introduce uniformity on the grounds of safety.
The earliest standardised method of wiring in buildings, in common use in North America from about 1880 to the 1930s, was knob and tube (K&T) wiring: single conductors were run through cavities between the structural members in walls and ceilings, with ceramic tubes forming protective channels through joists and ceramic knobs attached to the structural members to provide air between the wire and the lumber and to support the wires. Since air was free to circulate over the wires, smaller conductors could be used than required in cables. By arranging wires on opposite sides of building structural members, some protection was afforded against short-circuits that can be caused by driving a nail into both conductors simultaneously.
By the 1940s, the labour cost of installing two conductors rather than one cable resulted in a decline in new knob-and-tube installations. However, the US code still allows new K&T wiring installations in special situations (some rural and industrial applications).
In the United Kingdom, an early form of insulated cable, introduced in 1896, consisted of two impregnated-paper-insulated conductors in an overall lead sheath. Joints were soldered, and special fittings were used for lamp holders and switches. These cables were similar to underground telegraph and telephone cables of the time. Paper-insulated cables proved unsuitable for interior wiring installations because very careful workmanship was required on the lead sheaths to ensure moisture did not affect the insulation.
A system later invented in the UK in 1908 employed vulcanised-rubber insulated wire enclosed in a strip metal sheath. The metal sheath was bonded to each metal wiring device to ensure earthing continuity.
A system developed in Germany called "Kuhlo wire" used one, two, or three rubber-insulated wires in a brass or lead-coated iron sheet tube, with a crimped seam. The enclosure could also be used as a return conductor. Kuhlo wire could be run exposed on surfaces and painted, or embedded in plaster. Special outlet and junction boxes were made for lamps and switches, made either of porcelain or sheet steel. The crimped seam was not considered as watertight as the Stannos wire used in England, which had a soldered sheath.
A somewhat similar system called "concentric wiring" was introduced in the United States around 1905. In this system, an insulated electrical wire was wrapped with copper tape which was then soldered, forming the grounded (return) conductor of the wiring system. The bare metal sheath, at earth potential, was considered safe to touch. While companies such as General Electric manufactured fittings for the system and a few buildings were wired with it, it was never adopted into the US National Electrical Code. Drawbacks of the system were that special fittings were required, and that any defect in the connection of the sheath would result in the sheath becoming energised.
Armoured cables with two rubber-insulated conductors in a flexible metal sheath were used as early as 1906, and were considered at the time a better method than open knob-and-tube wiring, although much more expensive.
The first rubber-insulated cables for USA building wiring were introduced in 1922 with US patent 1458803, Burley, Harry & Rooney, Henry, "Insulated electric wire", issued 1923-06-12, assigned to Boston Insulated Wire And Cable. These were two or more solid copper electrical wires with rubber insulation, plus woven cotton cloth over each conductor for protection of the insulation, with an overall woven jacket, usually impregnated with tar as a protection from moisture. Waxed paper was used as a filler and separator.
Over time, rubber-insulated cables become brittle because of exposure to atmospheric oxygen, so they must be handled with care and are usually replaced during renovations. When switches, socket outlets or light fixtures are replaced, the mere act of tightening connections may cause hardened insulation to flake off the conductors. Rubber insulation further inside the cable often is in better condition than the insulation exposed at connections, due to reduced exposure to oxygen.
The sulphur in vulcanised rubber insulation attacked bare copper wire so the conductors were tinned to prevent this. The conductors reverted to being bare when rubber ceased to be used.
About 1950, PVC insulation and jackets were introduced, especially for residential wiring. About the same time, single conductors with a thinner PVC insulation and a thin nylon jacket (e.g. US Type THN, THHN, etc.) became common.
The simplest form of cable has two insulated conductors twisted together to form a unit. Such un-jacketed cables with two (or more) conductors are used only for extra low voltage signal and control applications such as doorbell wiring.
Other methods of securing wiring that are now obsolete include:
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. Similar surface mounted raceway wiring systems are still available today.
British Standard BS 7671 "Requirements for Electrical Installations. IET Wiring Regulations", informally called in the electrical community The "Regs", is the national standard in the United Kingdom for electrical installation and the safety of electrical wiring in domestic, commercial, industrial, and other buildings, also in special installations and locations, such as marinas or caravan parks.In general, BS 7671 applies to circuits supplied at nominal voltages up to and including 1000 volts AC or 1500 volts DC. The standard therefore covers the 230 volt 50 Hz AC mains supply used in the UK for houses, offices, and commerce. It did not become a recognized British Standard until the publication of the 16th edition in 1992. The standard takes account of the technical substance of agreements reached in CENELEC The current version is BS 7671:2018 (the 18th Edition) issued in 2018 and comes into effect from 1 January 2019. BS 7671 is also used as a national standard by Mauritius, St Lucia, Saint Vincent and the Grenadines, Sierra Leone, Sri Lanka, Trinidad and Tobago, Uganda, Cyprus, and several other countries, which base their wiring regulations on BS 7671.Ceiling rose
In the United Kingdom and Australia, a ceiling rose is a decorative element affixed to the ceiling from which a chandelier or light fitting is often suspended. They are typically round in shape and display a variety of ornamental designs.
In modern British wiring setups, light fittings usually use loop-in ceiling roses,which also include the functionality of a junction box.Copper conductor
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.Copper is the electrical conductor in many categories of electrical wiring. Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, and countless types of electrical equipment. Copper and its alloys are also used to make electrical contacts. Electrical wiring in buildings is the most important market for the copper industry. Roughly half of all copper mined is used to manufacture electrical wire and cable conductors.Electrical busbar system
Electrical Busbar System sometimes simply referred to as Busbar system is a modular approach to Electrical wiring, where in instead of standard cable wiring to every single electrical device, the electrical devices are mounted on to a adapter which is directly fitted to current carrying busbar. This modular approach is being used in distribution boards, Automation Panels & other power kinds of installation in an electrical enclosure.Busbar system is subject to safety standards for design and installation along with electrical enclosure according to IEC 61439-1 and vary by locality, country or region. & the system depends on Allowable Busbar types and sizes are vary according to operating voltage and current carrying capacity,Electrical cable
An electrical cable is an assembly of one or more wires running side by side or bundled, which is used to carry electric current.Electrical code
An electrical code is a set of regulations for the design and installation of electrical wiring in a building.
The intention of a code is to provide standards to ensure electrical wiring systems that are safe for people and property.
Such wiring is subject to rigorous safety standards for design and installation. Wires and electrical cables are specified according to the circuit operating voltage and electric current capability, with further restrictions on the environmental conditions, such as ambient temperature range, moisture levels, and exposure to sunlight and chemicals. Associated circuit protection, control and distribution devices within a building's wiring system are subject to voltage, current and functional specification. To ensure both wiring and associated devices are designed, selected and installed so that they are safe for use, they are subject to wiring safety codes or regulations, which vary by locality, country or region.
The International Electrotechnical Commission (IEC) is attempting to harmonise wiring standards amongst member countries, but large variations in design and installation requirements still exist.Electrical system design
Electrical system design is the design of electrical systems. This can be as simple as a flashlight cell connected through two wires to a light bulb or as involved as the space shuttle. Electrical systems are groups of electrical components connected to carry out some operation. Often the systems are combined with other systems. They might be subsystems of larger systems and have subsystems of their own. For example, a subway rapid transit electrical system is composed of the wayside electrical power supply, wayside control system, and the electrical systems of each transit car. Each transit car’s electrical system is a subsystem of the subway system. Inside of each transit car there are also subsystems, such as the car climate control system.Electrical wiring in North America
Electrical wiring in North America follows regulations and standards for installation of building wiring which ultimately provides mains electricity.Electrical wiring in the United Kingdom
Electrical wiring in the United Kingdom is commonly understood to be an electrical installation for operation by end users within domestic, commercial, industrial, and other buildings, and also in special installations and locations, such as marinas or caravan parks. It does not normally cover the transmission of electrical power to them.
Installations are distinguished by a number of criteria, such as voltage (high, low, extra low), phase (single or 3 phase), nature of electrical signal (power, data), type and design of cable (conductors and insulators used, cable design, solid/fixed or stranded/flexible, intended use, protective materials), circuit design (ring, radial), and so on.
Electrical wiring is ultimately regulated to ensure safety of operation, by such as the Building Regulations, currently legislated as the Building Regulations 2010, which lists "controlled services" such as electric wiring that must follow specific directions and standards, and the Electricity at Work Regulations 1989. The detailed rules for end-use wiring followed for practical purposes are those of BS 7671 Requirements for Electrical Installations. (IET Wiring Regulations), currently in its 18th edition, which provide the detailed descriptions referred to by legislation.
UK electrical wiring standards are largely harmonised with the regulations in other European countries and the international IEC 60446 standard. However, there are a number of specific national practices, habits and traditions that differ significantly from other countries, and which in some cases survived harmonisation. These include the use of ring circuits for domestic and light commercial fixed wiring, fused plugs, and for circuits installed prior to harmonisation, historically unique wiring colours.Electrician
An electrician is a tradesman specializing in electrical wiring of buildings, transmission lines, stationary machines, and related equipment. Electricians may be employed in the installation of new electrical components or the maintenance and repair of existing electrical infrastructure. Electricians may also specialize in wiring ships, airplanes, and other mobile platforms, as well as data and cable lines.Gardner Bender
Gardner Bender is a manufacturer of professional electricians' tools and supplies. The company has a long history, starting as the brainchild of Jim Gardner, a master mechanic in a Milwaukee aluminum can plant who spent his free time as an inventor. In 1959, after watching the electricians at the plant struggle with an inferior device, Gardner invented an aluminum pipe bender so promising that he decided to manufacture it himself. Today, Gardner Bender manufactures electrical tools, voltage testers, wire management products and other professional equipment.Household hardware
Household hardware (or simply, hardware) is equipment that can be touched or held by hand such as nuts, screws, washers, keys, locks, hinges, latches, handles, wire, chains, belts, plumbing supplies, electrical supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores.IEC 60038
International Standard IEC 60038:1983 defines a set of standard voltages for use in low voltage and high voltage AC electricity supply systems.IEC 60446
International standard IEC 60446 Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors defines basic safety principles for identifying electrical conductors by colours or numerals, for example in electricity distribution wiring. The standard has been withdrawn; the fourth edition (IEC 60446:2007) was merged in 2010 into the fifth edition of IEC 60445 along with the fourth edition, IEC 60445:2006.Ideal Industries
Ideal Industries is an American company that produces connectors, hand tools, testers, and meters for the electrical and telecommunications industries.The company manufactures many of its products in the United States. It also owns Western Forge and Pratt-Read, the largest– and second-largest American-made producers of screwdrivers respectively at the time of their acquisitions.It is a competitor to Klein Tools, and its tools are sold at Lowe's and Ace Hardware stores as well as many independent distributors.Rat-tail splice
A rat-tail splice, also known as a twist splice or a pig-tail splice, is a very basic electrical splice that can be done with both solid and stranded wire. It is made by taking two or more bare wires and wrapping them together symmetrically around the common axis of both wires. The bare splice can be insulated with electrical tape or other means.
This common and simple splice is not very strong mechanically. It can be made stronger by coating it with solder, or it can be twisted and then held in place by the internal metal spring or threads of a twist-on wire connector, also called a wire nut. Because it is not very strong, the splice is not meant to connect wires that will be pulled or stressed. Rather, it is intended for wires that are protected inside an enclosure or junction box.T-splice
In electrical wiring, a T-splice is a splice that is used for connecting the end of one wire to the middle of another wire, thus forming a shape like that of the letter "T." This splice can be used with solid or stranded wires. The existing wire is called the main wire. The new wire that connects to the main wire is called the branch wire or tap wire. This is a prevalent junction type used in knob and tube wiring.Western Union splice
The Western Union or Lineman splice was developed during the introduction of the telegraph to mechanically and electrically connect wires that were subject to loading stress. The wrapping pattern is designed to cause the termination to tighten as the conductors pull against each other. This type of splice is more suited to solid, rather than stranded conductors.The Western Union Splice is made by twisting two ends of a wire together, traditionally counterclockwise, 3/4 of a turn each, finger tight. Then, usually using needle-nose pliers, the ends are twisted at least five more turns, tightly. The cut off ends are pushed close to the center wire.
"Short tie" and "long tie" variations exist, mainly for purposes of coating the connection with solder. The longer version may aid in solder flow.NASA tests on 22 and 16 AWG wire showed that the Western Union Splice when soldered is very strong and is stronger than the wire alone if done properly.Wiring closet
A wiring closet is a small room commonly found in institutional buildings, such as schools and offices, where electrical connections are made. While they are used for many purposes, their most common use is for computer networking where it may be called a Premises Wire Distribution (PWD) Room. Many types of network connections place limits on the distance between end user equipment, such as personal computers, and network access devices, such as routers. These restrictions might require multiple wiring closets on each floor of a large building.
Equipment that may be found in a wiring closet includes:
Circuit breaker panels
Video systems, such as cable TV and closed-circuit television systems
Ethernet routers, Network switches, Firewalls
Fiber optic terminations
Telephone punch blocks
Wireless access points