Definition of electric power industry
The electric power industry is the generation, transmission, distribution and sale of electric power to the general public. The electrical industry started with introduction of electric lighting in 1882. Throughout the 1880s and 1890s, growing economic and safety concerns lead to the regulation of the industry. Once an expensive novelty limited to the most densely populated areas, reliable and economical electric power has become a requirement for normal operation of all elements of developed economies.
By the middle of the 20th century, electric power was seen as a "natural monopoly", only efficient if a restricted number of organizations participated in the market; in some areas, vertically-integrated companies provides all stages from generation to retail, and only governmental supervision regulated the rate of return and cost structure.
Since the 1990s, many regions have opened up the generation and distribution of electric power to provide a more competitive electricity market. While such markets can be abusively manipulated with consequent adverse price and reliability impact to consumers, generally competitive production of electrical energy leads to worthwhile improvements in efficiency. However, transmission and distribution are harder problems since returns on investment are not as easy to find.
kWh - definition
The symbol "kWh" is commonly used in commercial, educational, scientific and media publications,4 and is the usual practice in electrical power engineering.
Other abbreviations and symbols may be encountered:
"kW h" is less commonly used. It is consistent with SI standards (but note that the kilowatt-hour is a non-SI unit). The international standard for SI states that in forming a compound unit symbol, "Multiplication must be indicated by a space or a half-high (centered) dot (?), since otherwise some prefixes could be misinterpreted as a unit symbol" (i.e., kW h or kW?h). This is supported by a voluntary standard6 issued jointly by an international (IEEE) and national (ASTM) organization. However, at least one major usage guide and the IEEE/ASTM standard allow "kWh" (but do not mention other multiples of the watt hour). One guide published by NIST specifically recommends avoiding "kWh" "to avoid possible confusion".
The US official fuel-economy window sticker for electric vehicles uses the abbreviation "kW-hrs".
Variations in capitalization are sometimes seen: KWh, KWH, kwh etc.
"kW?h" is, like "kW h", preferred with SI standards, but it is very rarely used in practice.
The notation "kW/h", as a symbol for kilowatt-hour, is not correct.
Wholesale for electricians
Many electricians providing electrical services, such as repair of electrical installations requires reliable and proven place where they could procure the necessary materials such as, for example, cables or wires. Therefore, many people in the industry decides to cooperate with the wholesale of electrical materials. Without the proper equipment electrician it is not yet able to perform even the simplest repairs requiring hardware replacement. Wholesale materials allow electrical supply is needed in these articles; mediate between the manufacturer and individual customers.