electri theory

8/7/2019 Electri Theory

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What is Electricity?

What is "electricity?" It is much easier to describe what it does than what it is. Forexample, electricityoperates our Lights, runs our Refrigerators and powers ourElectric Motors.

Electricity is actually defined as: " the movement (or flow) of Electrons through amaterial."

The word "electric" comes from the Greek word "amber" and has been used todescribe a wide range of related phenomena. We cannot see electricity, but wecan see its effects (i.e. light).

Electricity can exist in a number of forms; however, there are two types ofcommonly used electricity:

1. Direct Current: which is commonly provided by Batteries; and2. Alternating Current: provided by Electric Utilities or other Power

Generators in the form ofElectrons (called "current") flowing through a Wirecalled a "Conductor."

House Wiring

Wiring, or what we call building wiring, is the process of providing power to buildings and structures.

Conductors carry electricity, and wiring makes this power available for public use. National and localregulations in a locality have a check on installation of wiring procedures. In some countries a single

national body is in charge of electrical installations and safety codes, while in some countries a national

technical standard body produces a model electrical code, which is then adopted by the state, city or

provincial regulations with slight changes as per their requirements.

House Wiring Methods

The function of wiring safety codes is to give technical, performance and material standards that would

allow proper use of the electrical energy. Other preventions that are regulated are electric shock, fire or

explosion. Materials required for wiring a building depend on factors like rating of the circuit, type of

occupancy of the building, type of electrical system, national and local regulations and conditions in

which the wiring must operate. Earlier methods of wiring were single cloth- insulated copper conductors

running in interior walls. Another method was re-using of existing gas pipes for electric lighting. Then

came Modern nonmetallic-sheathed cables (NMC), consisting of two to four thermoplastic insulated

wires and a bare wire for grounding surrounded by a flexible plastic jacket.

In industries, conductor bars are assembled with insulators in grounded enclosures. For heavy currents, bus bars are

used. A live conductor of this type is a rigid piece of copper or aluminum usually in flat bars. Open bus bars are also

used in manufacturing plants and power company switchyards. Such a bus set up can provide up to 50,000 amperes


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and up to hundreds of kilovolts. Much advancement is being made in wiring methods. The use of this scheme is the

ability to remove/add a branch circuit without removing voltage from the whole segment. A fault in any phase jumps to

the ground. Some common wiring tools are Lineman's pliers, Needle-nose pliers, wire strippers cable cutters rotosplit

multimeter screwdrivers, crimpers, hammers, reciprocating saws, drywall saws, metal punches, flashlights, chisels and

adjustable pliers.

This article includes a list of references, related reading or external links, but its

sources remain unclear because it lacks inline citations. Please improvethis

article by introducing more precise citations where appropriate. (August 2010)

In electricity supply systems, an earthing system defines the electrical potentialof the conductors relative to that of the Earth's conductive surface. The choice ofearthing system has implications for the safety and electromagnetic compatibilityof the power supply. Note that regulations for earthing (grounding) systems varyconsiderably among different countries.

Aprotective earth (PE) connection ensures that all exposed conductive surfacesare at the same electrical potential as the surface of the Earth, to avoid the risk ofelectrical shock if a person touches a device in which an insulation fault hasoccurred. It ensures that in the case of an insulation fault (a "short circuit"), a veryhigh current flows, which will trigger an overcurrent protection device (fuse, circuitbreaker) that disconnects the power supply.

A functional earth connection serves a purpose other than providing protectionagainst electrical shock. In contrast to a protective earth connection, a functionalearth connection may carry a current during the normal operation of a device.Functional earth connections may be required by devices such as surge

suppression and electromagnetic interference filters, some types ofantennas andvarious measurement instruments. Generally the protective earth is also used as afunctional earth, though this requires care in some situations.

List of Other Electrical Appliances and Materials 338 items (Category B)

Appendix 2 (related to Article 1)
http://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:External_linkshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sources#Inline_citationshttp://en.wikipedia.org/wiki/Wikipedia:WikiProject_Fact_and_Reference_Checkhttp://en.wikipedia.org/wiki/Wikipedia:WikiProject_Fact_and_Reference_Checkhttp://en.wikipedia.org/wiki/Wikipedia:When_to_citehttp://en.wikipedia.org/wiki/Electricity_supplyhttp://en.wikipedia.org/wiki/Ground_(electricity)http://en.wikipedia.org/wiki/Electrical_potentialhttp://en.wikipedia.org/wiki/Safetyhttp://en.wikipedia.org/wiki/Electromagnetic_compatibilityhttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Electrical_shockhttp://en.wikipedia.org/wiki/Surge_suppressionhttp://en.wikipedia.org/wiki/Surge_suppressionhttp://en.wikipedia.org/wiki/Electromagnetic_interferencehttp://en.wikipedia.org/wiki/Antenna_(radio)http://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:External_linkshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sources#Inline_citationshttp://en.wikipedia.org/wiki/Wikipedia:WikiProject_Fact_and_Reference_Checkhttp://en.wikipedia.org/wiki/Wikipedia:When_to_citehttp://en.wikipedia.org/wiki/Electricity_supplyhttp://en.wikipedia.org/wiki/Ground_(electricity)http://en.wikipedia.org/wiki/Electrical_potentialhttp://en.wikipedia.org/wiki/Safetyhttp://en.wikipedia.org/wiki/Electromagnetic_compatibilityhttp://en.wikipedia.org/wiki/Fuse_(electrical)http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Electrical_shockhttp://en.wikipedia.org/wiki/Surge_suppressionhttp://en.wikipedia.org/wiki/Surge_suppressionhttp://en.wikipedia.org/wiki/Electromagnetic_interferencehttp://en.wikipedia.org/wiki/Antenna_(radio)


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Cables, cords and heating cables as noted below:

1) Non-sheathed rigid cables as noted below (limited to those havingconductors of nominal cross-sectional area of 100 mm2 or less):

(1) Fluorescent lamp cables

(2) Neon tube cables

2) Rigid cables (limited to those with a rated voltage of not less than 100 Vbut not more than 600V, having conductors of nominal cross-sectional areaof exceeding 22 mm2 but not more than 100 mm2 or less, having corescomposed of seven strands or less, and having sheaths of rubber [includingsynthetic rubber], or of synthetic resin)

3) Floor heating cables

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Wireways, fittings, and cable wiring switch boxes as noted below (excludingthose constructed of copper or bronze, or explosion-proof types):

1) Conduits (limited to those with inner diameter of 120 mm or lessincluding flexible conduits)

2) Underfloor ducts (limid to those with a width of 100 mm or less)

3) Raceways (limited to those with a width of 50 mm or less)

4) Fittings of conduits (limited to those connected to the conduits noted in1) above, the underfloor ducts noted in 2) above, and the raceways notedin 3) above, or those connected to the ends of said conduits, underfloorducts, or raceways, but excluding reducers)

5) Cable wiring switch boxes

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Fuses as noted below (limited to those having a rated voltage of not lessthan 100 V but not more than 300 V and those having a rated current ofnot less than 1 A but not more than 200 A [in the case of fuses forelectrical motors, limited to those used with motors rated 12 kW or less],for use in alternating current circuits)

1) Cartridge fuses

2) End contact plug fuses

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Wiring devices as noted below (limited to those having a rated voltage ofnot less than 100 V but not more than 300 V for use in alternating currentcircuits, but excluding explosion proof and oil-filled types):

1) Remote control relays (limited to those having a rated current of 30 A orless, and excluding those specially designed to be incorporated inappliances)

2) Switching devices as noted below (limited to those having a ratedcurrent of 100 A or less [in the case of switches for electrical motors,limited to those used with motors rated 12 kW], but excluding thosespecially designed to be incorporated in appliances):

(1) Cutout switches


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