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Basic electric knowledge - wires
Wiring safety codes are intended to protect people and property from electrical shock and fire hazards. Regulations may be established by city, county, provincial/state or national legislation, usually by adopting a model code (with or without local amendments) produced by a technical standards-setting organisation, or by a national standard electrical code.
Electrical codes arose in the 1880s with the commercial introduction of electrical power. Many conflicting standards existed for the selection of wire sizes and other design rules for electrical installations.
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 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.
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 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.
The international standard wire sizes are given in the IEC 60228 standard of the International Electrotechnical Commission. In North America, the American Wire Gauge standard for wire sizes is used.
Building wiring is the electrical wiring and associated devices such as switches, meters and light fittings used in buildings or other structures. Electrical wiring uses insulated conductors.
Wires and cables are rated by the circuit voltage, temperature and environmental conditions (moisture, sunlight, oil, chemicals) in which they can be used, and their maximum current. Wiring safety codes vary by country, and the International Electrotechnical Commission (IEC) is attempting to standardise wiring amongst member countries. Colour codes are used to distinguish line, neutral and earth (ground) wires.
Definition of electritian
In the United States, electricians are divided into two primary categories: linemen, who work on electric utility company distribution systems at higher voltages, and wiremen, who work with the lower voltages utilized inside buildings. Wiremen are generally trained in one of five primary specialties: commercial, residential, light industrial, industrial, and low-voltage wiring, more commonly known as Voice-Data-Video, or VDV. Other sub-specialties such as control wiring and fire-alarm may be performed by specialists trained in the devices being installed, or by inside wiremen.
Electricians are trained to one of three levels: Apprentice, Journeyman, and Master Electrician. Apprentices in the US and Canada are working to learn the electrical trade. They generally take several hundred hours of classroom instruction and are contracted to follow apprenticeship standards for a period of between three and six years, during which time they are paid as a percentage of the Journeyman's pay. Journeymen are electricians who have completed their Apprenticeship and who have been found by the local, State, or National licensing body to be competent in the electrical trade. Master Electricians have performed well in the trade for a period of time, often seven to ten years, and have passed an exam to demonstrate superior knowledge of the National Electrical Code, or NEC.
Service electricians are tasked to respond to requests for isolated repairs and upgrades. They have considerable skills troubleshooting wiring problems, installing wiring in existing buildings, and making repairs. Construction electricians primarily focus on larger projects, such as installing all new electrical system for an entire building, or upgrading an entire floor of an office building as part of a remodeling process. Other specialty areas are marine electricians, research electricians and hospital electricians. "Electrician" is also used as the name of a role in stagecraft, where electricians are tasked primarily with hanging, focusing, and operating stage lighting. In this context, the Master Electrician is the show's chief electrician. Although theater electricians routinely perform electrical work on stage lighting instruments and equipment, they are not part of the electrical trade and have a different set of skills and qualifications from the electricians that work on building wiring.
In the film industry and on a television crew the head electrician is referred to as a Gaffer.
Electrical contractors are businesses that employ electricians to design, install, and maintain electrical systems. Contractors are responsible for generating bids for new jobs, hiring tradespeople for the job, providing material to electricians in a timely manner, and communicating with architects, electrical and building engineers, and the customer to plan and complete the finished product.