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Sunday, December 13, 2009

Types of electrical wiring

Residential wiring is less complex then commercial electrical wiring. In most residential applications cable is used instead of conduit and wire. There are several wire types that are generally used in residential wiring.

The first type of electrical wire is NM wire. This is the most used in residential applications. There are usually two wires and a bare ground wire which is wrapped in a type of paper. All three wires are protected by a plastic wire coating called sheathing. The ground wire will be positioned in between the two conductors. This type of wire is not made for wet or high moisture situations.

The wire that is designed for high moisture applications is NMC. In this type of wire all thee wires are enclosed in plastic. This type of wire is used predominantly in crawlspaces and in basements.

Type UF wire is used in outdoor applications. This type of wire is predominantly used to supply power to exterior lighting. This wire is also enclosed in plastic casings.

In older homes BX armored cable was used. This type of electrical wire is covered with a metal cover and was used because it is difficult to damage and to puncture. This type of wire is very durable and has the advantage of having the metal covering act as a grounding mechanism. BX wire is not used in most residential applications today because of its cost and difficulty of installation. Usually this type of wire is used in modern commercial applications.

Electrical wire is sized by gauge numbers. Correct wire sizing id very important in residential and commercial buildings. Of too small a wire is used it can overheat if it is not capable of carrying the current placed on it. When this occurs it can blow a fuse or trip a breaker or in the worst case it can cause a fire.

Types of electrical wire

Types of electrical wire usually separated in 3 category:
  • Power cable

  • control cable

  • Instrument cable.

  • You may familiar with some Insulation and Jacket type such as
    THHN/THWN
    PVC/NYLON
    FR-XLP
    RHW-2 OR RHH OR USE-2
    FR-XLP
    HMWPE, LSZH.

    Here are only few cable types and their applications example:

    600 V THHN Copper conductor: For use in general wiring application and power in conduit.
    600 V RHW-2 Copper Conductor: For use in harsh environments for general wiring direct burial.
    300 V UL type PLTC: This is a multi-pair instrumentation cable: For use in instrumentation and process control applications

    Copper Electrical Wire
    Copper is the common used because copper is a very good conductor, and is easy to mold and bend.

    Aluminum Electrical Wire
    Aluminum is cheaper and more abundant than copper. It is also easy to shape and bend.
    More important for electrical designer is to select the right size of electrical wire . The following link is the method of how to determine cable size.


    Electrical Wire Size


    Before selecting electrical cable, There are much more but here are just some criteria s to keep in mind :

  • Cable conductors

  • Cable AWG

  • Temperature

  • Shield type

  • Material type

  • No of pairs



  • Electrical wire size using table 310.16 NEC2008 on page 70-148. Simply calculate amperage (current) flow through the circuit and then apply the table.

    SIZE AWG OR KCMIL COPPER COPPER COPPER ALUMINUM ALUMINUM ALUMINUM SIZE AWG OR KCMIL
    _ TYPE TW,UF TYPES RHW
    ,THHW,THW,
    THWN,XHHW
    USE,ZW
    RHW-2,THHN
    THHW,THW-2
    (90°C)
    TYPES TW,UF
    (60°C)
    TYPES RHW
    THHW,THW
    THWN,XHHW
    USE
    TYPES TBS,SA
    SIS,THHW<>
    SIZE AWG OR KCMIL
    18
    16
    14
    12
    10
    8
    _
    _
    20
    25
    30
    40
    _
    _
    20
    25
    35
    50
    14
    18
    25
    30
    40
    55
    _
    _
    _
    20
    25
    30
    _
    _
    _
    20
    30
    40
    _
    _
    _
    25
    35
    45
    _
    _
    _
    12
    10
    8
    6
    4
    3
    2
    1
    55
    70
    85
    95
    110
    65
    85
    100
    115
    130
    75
    95
    110
    130
    150
    40
    55
    65
    75
    85
    50
    65
    75
    90
    100
    60
    75
    85
    100
    115
    6
    4
    3
    2
    1
    1/0
    2/0
    3/0
    4/0
    125
    145
    165
    195
    150
    175
    200
    230
    170
    195
    225
    260
    100
    115
    130
    150
    120
    135
    155
    180
    135
    150
    175
    205
    1/0
    2/0
    3/0
    4/0
    250
    300
    350
    400
    500
    215
    240
    260
    280
    320
    255
    285
    310
    335
    380
    290
    320
    350
    380
    430
    170
    190
    210
    225
    260
    205
    230
    250
    270
    310
    230
    225
    280
    305
    350
    250
    300
    350
    400
    500
    600
    700
    750
    800
    900
    335
    385
    400
    410
    435
    420
    460
    475
    490
    520
    475
    520
    535
    555
    585
    285
    310
    320
    330
    335
    340
    375
    385
    395
    425
    385
    420
    435
    450
    480
    600
    700
    750
    800
    900
    1000
    1250
    1500
    1750
    2000
    435
    495
    520
    545
    560
    545
    590
    625
    650
    665
    615
    665
    705
    735
    750
    375
    405
    435
    455
    470
    445
    485
    520
    545
    560
    500
    545
    585
    615
    630
    1000
    1250
    1500
    1750
    2000

    Apply table to calculate electrical wire size
    Assume the current calculated result is 14A, cable type is copper THHN, insulated conductors rated at 90° C, and so based on the table, cable size is 18 AWG. For practical safety application, recommended power cable should be bigger than 12 AWG.



    Wire size calculator

    Wire Size Calculator
    Select Voltage
    120V 208V 240V 277V 480V
    Select Wire Type

    Copper Aluminum
    Select Phase

    Single Phase Three Phase
    Input Amperage Input One Way Distance (in feet)
    Minimum Size Required



    Basic Electrical Overview

    The most basic principles of the wiring in your home are simple. The following is elementary information from which every homeowner can benefit:
    In existing wiring, individual wires run in a enclosed cable. "Two-wire with ground" and "three-wire with ground" cables are available. Two-wire with ground cables have a black wire, a white wire and a UN insulated ground. Three-wire with ground cables have a black wire, a white wire, a red wire and an uninsulated ground. Older houses may have "knob and tube" wiring—a two-wire system. With this system, individual wires are insulated with white or black treated fabric.

    Regardless of the type of cabling in your home, the white wire is usually the neutral wire, the black wire is "hot," and the exposed copper wires are ground wires. The white wire is sometimes used as a hot wire because some wiring installations oblige it. In this case, the white wire should be coded black with paint or electrical tape. Note, however, that it is possible that whoever did the wiring may not have coded the wire. If a red wire is present, it should also be hot.


    Switches may be energetic at the end or in the middle of a circuit. If only a single cable enters the box, the fixture is at the end of the circuit. This is usually, but not always, the position with ceiling light fixtures. If two cables enter the box (or two sets of black and white wires in older "knob and tube" installations), the fixture is in the middle of a circuit. A third cable (or set of black and white wires) may also enter the fixture, depending upon the installation. The placement of the fixture within the circuit affects how it is wired.


    The black, or hot wires, are joined to the brass screw terminals on receptacles and switches. The neutral wires are joined to the silver terminals. Ground wires should not be disregarded .They should be connected to each other, to the grounding screw terminals (painted green) on receptacles, and to grounding screws in metal electrical boxes when metal boxes are used.


    Pigtail leads are short wires which are connected to terminals on receptacles or switches. The leads are then connected to the home wiring using plastic wire connectors. Codes in some areas require that pigtails be used on all standard receptacle connections. Always use pigtails when more than one wire must be connected to a single terminal.


    What is Electrical Wire?

    Electrical wire is the standard during which electricity is passed to and through each individual home that uses electrical power. It is made of a metal that easily conducts electricity, usually copper, in a plastic sheath called an insulator. There are different types of electrical wire, each suited to firm loads and conditions. Four main types are ordinary in residential applications.


    The first type is triplex wire, which is the cable that runs aerially between outdoor power poles. Often in triplex wire, there are three wires cruel together: two insulated ones carrying the line voltage, and the other being a bare, neutral wire. The second type, main feeder wires, runs between a power pole and the house that the power is being brought to. These wires are usually rated for 125% of the load they are required to carry.

    The other two types of electrical wire run through the walls and power outlets of a house. Panel feed wires are rated at 125 amps, to take power into a main junction box or circuit breaker panel, and they provide the hookup from which the other wiring in a house branches out. This type of electrical wire is inexpensive and well-suited to dry indoor applications.

    In the United States, acceptable electrics methods are specified by the National Electrical Code (NEC). Local jurisdictions will usually adopt the NEC and then vary the local code from it slightly. The NEC is not necessary to be the electrical code for any jurisdiction, but rather it is simply an leading set of standards used by local governments for purposes of regulation. Its intent is to protect people from hazards that arise from the improper use of electricity.

    One example of an NEC guideline would be the provision that the grounding wire in a circuit be either bare or have green insulation. The NEC also states that large appliances such as furnaces, stoves, and central air conditioning units should be on a devoted circuit. The guidelines of the NEC receive changes and updates from time to time, but existing installations are generally not required to make changes to conform to the new code. New buildings are required to adhere to whatever electrical standards are set forth by local authorities.

    How Electric Car Works

    Electric cars are exposed up in the news these days .The hybrid vehicles and particularly the electric cars are talk of the town. The electric car is the best option for the petroleum cars. The cause for this includes many statements. The electric cars have a lot of compensation over the old formed petroleum cars. The popularity of the electric cars has reached roughly all over the world. We are taught in schools about the different sources of energy. The alternative sources of energy are solar energy, gas energy, electrical energy, etc. The electric cars are the cars which can run on electricity. Essentially the petroleum cars can also be converted into electric cars. It is very easy to convert a petroleum car into electric cars. The majority of the petroleum cars are being improved into electrical cars as electrical cars is cost cutting.


    It is almost not difficult to comprehend how an electric car works. The architecture of the electric car is fairly different then the petroleum car. An electrical car is consisting of lots of wiring. The electrical car has following main components:


    Electric Motor

    Motor Controller

    Batteries


    An electric car is powered by an electric motor since a petroleum car is powered by a petroleum engine. This is how an electric car defers from the petroleum car. Instead of a petroleum engine an electric motor is placed within the electric car. The electric motor gets power from the controller. Number of rechargeable batteries provides power to the controller.


    The controller gets the power from the batteries and gives it to the motor. The accelerator pedal is tied with a pair of potentiometers (variable resistors), which provides the signal for the controller how much power it is to to deliver.


    The 300 volts dc current is input to the controller from the battery and controller converts it into a maximum of 240 volts AC, three-phase, and sends to the motor. Inside the controller there is a transistor which turns on and off rapidly. A connector connects these two potentiometers and the pedal, when you push on the gas pedal, The controller gets information about how much power to deliver to the electric car's motor from the potentiometers. There are two potentiometers for the sake of safety. The controller checks the readings of the both potentiometers to be equal. If they are not, then the controller stops operating. When accsilator is pressed, the regulator turns the switch on, and when it is removed, it would turn it off.


    The batteries are the main sources of power for the electrical car. Number of rechargeable batteries provides power to the controller. The motor can use both AC and DC batteries. Batteries run by chemicals such as lithium. You can recharge the batteries by just plugging in the wire to the electric socket.

    What is Electrical Engineering?

    Electrical engineering is apprehensive with the essential forms of energy that run our world. Whether it's gas, hydro, turbine, fuel cell, solar, geothermal, or wind energy, electrical engineers deal with distributing these energies from their sources to our homes, factories, offices, hospitals, and schools. Electrical engineering also involves the moving field of electronics and information technology. Do you have a cellular phone or a computer? Wireless communication and the Internet are just a few areas electrical engineering has helped flourish, by developing better phones, more powerful computers, and high-speed modems. As we enter the 21st century, the technology that surrounds us will continue to enlarge and electrical engineers are top the way.


    What do Electrical Engineers do?

    With electricity and light (photons), electrical engineers apply specific engineering skills to the design; make application, installation and operation of electrical products and systems.

    Almost all we use and rely on in our everyday life has an electrical element from the microwave that heats up our food, to the computer we use at work, the computer games we play with, the television we watch, and the cell phone we use to keep in touch -- all relies on electricity, electronics, computer chips and/or programming. The analytical equipment used in hospitals is also designed by electrical engineers working in the field of biomedical engineering. Electrical engineers keep the world in touch and running easily by designing new devices or improving on existing ones. For example by designing a smaller, cheaper and more powerful cell phone.

    Electrical tools can be mutual with other fields of engineering, such mechanical engineering and biomedical engineering in the case of designing an synthetic limb for the victim of an accident. Electrical engineering offers a wide range of research in areas as varied as communications, systems control, biomedical engineering, electromagnetic, photonics, electronics and energy systems.

    What is Electrical Energy?

    Electrical energy is the occurrence and current of an electric charge. The power portion of electricity is start in a range of phenomena such as static electricity, electromagnetic fields and lightning. Humans have start the ability to attach these phenomena and store the electrical accuse for later use. The concept of electrical energy is clear using a variety of dissimilar terminologies such as charge, current and potential.


    Electrical energy is the result of the interface of subatomic particles with electromagnetic force. Within an atom, electrons and protons create a charge. This charge can be transferred among bodies using direct contact with a conductive object like a wire.

    The current refers to the faction of the charge. With direct current, this occurs when the electricity is stored in a battery and travels in one route out of the battery. Alternating current occurs when the current changes direction constantly within an electrical system. The alternating current type is usually used to power bigger objects such as residences and buildings.

    Electrical potential is necessary to the range and power of electric energy. When an electric charge exists within an object, a force is exerted from its electrical field. This accelerates the object in a direction each towards or away from the charge, depending on the electromagnetic division generally, positively-charged electricity pushes the object away, while negatively-charged electricity pulls the object towards the field.

    Electrical energy can be generated using a diversity of means. The flaming of fossil fuels or the heat from nuclear reactions produces vapor that powers a generator which, in turn, creates electricity. Otherwise, kinetic energy extracted from either wind or water can power analogous generators. All of these methods require a transformer that modifies the electrical energy into a higher voltage with lower current. Different methods of storing this energy include capacitors and batteries.

    The oldest recognized civilization that understood electrical energy were the antique Egyptians. Texts from 2750 BC refer to the “Thunderer of the Nile” and define the shocks of electric fish. Knowledge and study of the fish continued through the millennia with Greek, Roman and Arab scholars. Pliny the Elder and Scribonius Largus researched the numbing effects of electric shocks. In addition, a number of Arab scientists firm the same phenomena caused lightning.


    Until 1600, much of the understanding of electricity as an energy source was purely intellectual. William Gilbert, an English physician, studied electricity and magnetism. A number of other researchers continued the study including Otto von Guericke, Robert Boyle and Benjamin Franklin. By the 1800s, scientists such as Alessandro Volta had identified a way to attach electricity into a battery format.