Electrification

Electricity & Electrification

In general usage, the word “Electricity" is adequate to refer to a number of physical effects. In scientific usage, however, the term is vague, and these related, but distinct, concepts are better identified by more precise terms:Electric charge – a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields. Electric current – a movement or flow of electrically charged particles, typically measured in amperes. Electric field – an influence produced by an electric charge on other charges in its vicinity.

Introduction

Terms & Definitions

The three most basic units in Electricity are: Voltage (V), Current (I, uppercase "i") and Resistance (r). • Voltage is measured in VOLTS.• Current is measured in AMPS and • Resistance is measured in OHMS.

Amperage or Amps provided by an electrical service is the flow rate of "electrical current " that is available. Mathematically, Amps = Watts / Volts. (Amps = Watts divided by Volts)

Volt is defined as the potential difference across a conductor when a current of one ampere dissipates one watt of power.

Watt is a measure of the amount of electricity being used - a rate of electrical power consumption.

To determine how many watts an electrical circuit can carry or how many watts an electrical device will require: Watts = Volts x Amps.

HOW ELECTRICITY TRAVELS

Electricity travels along a path. If the path is blocked,    then electricity cannot keep flowing. The whole path along which electricity  travels is known  as a circuit. A broken path is known as an 'Open Circuit' and the electricity  can not flow in an open  circuit. An unbroken path is known as a 'Closed  Circuit' and the electricity can flow.Excess loading/ Overloading of electricity:It is an electrical load that exceeds the available electrical power.

Ground: means the physical earth, the soil or ground. In some countries the term earth is used and is synonymous with ground. In the electrical code, ground means an electrically conducting connection, intentional or accidental, between an electrical circuit and the earth. Grounded means that something has been electrically connected to the earth. Grounding electrode or ground electrode: a metal conductor, usually a solid copper-alloy rod of specified length, driven into the ground in order to provide a point for electrical connection between the building grounding system and ground or earth. Grounded Conductor (the NEUTRAL wire): by convention the grounded conductor or neutral wire is white or gray. In an electrical circuit the grounded conductor normally carries electrical current between the un-grounded (hot) electrical wire and (back through the main electrical panel and grounding system) earth.

Earthing

Equipment Grounding Conductor (the ground wire): By convention the equipment grounding conductor (ground wire) is bare copper or carries green insulation. the individual wire in a (grounded) electrical circuit that is connected through the ground bus in the electrical panels and ultimately in the main electrical panel is connected to ground or earth. In the electrical code, a grounding conductor is a conductor (metal wire, metal bar, etc) which is used to connect electrical equipment (like an electrical panel enclosure) or the grounded circuit (the neutral wires) of a wiring system to a grounding electrode (and thus to earth).

What is short circuit? Short circuit occurs due to accidental contact of phase with another phase or phase with neutral or phase with earth wire.

Earthing

Electric meter:The meter is a watt measuring device supplied by the utility company to track each month’s power consumption. There are meters with numbered dials like a watch on older models and new state-of-the-art digital meters that can be read right from the utility company’s office.

Electrical panel:The electrical panel, breaker box, fuse box or service panel is the next device in line. This panel’s job is to distribute power throughout your home and disconnect power from the incoming feed. Grounding wire:The service must be connected to a ground rod outside the house and also bonded around the water meter in the house. A jumper connected on both sides of the meter must be made to allow the meter to be removed without losing a ground connection.

Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. This article describes general aspects of electrical wiring as used to provide power in buildings and structures, commonly referred to as building wiring.

Materials for wiring interior electrical systems in buildings vary depending on:

Intended use and amount of power demand on the circuit Type of occupancy and size of the building National and local regulations Environment in which the wiring must operate.

Electrical Wiring

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 equipments in hazardous area.

Standard wire colours for Single phase -

Live/Phase : Red Neutral : BlackProtective earthing/ground : Green

Standard wire colours for Three Phase-

Live/Phase : RedLive/Phase : YellowLive/Phase : BlueNeutral : Black Protective earthing/ground : Green

Mains Meter Cabinet to D.B. in flat

Phase

Neutral

Earth

Red

Black

Green

7/20

7/20

1/18

7/0.914

7/0.914

1/1.120

Circuits

or

Sub- mains

D.B. to room S.B. or Kitchen

___power point___

D.B. to bathroom

(for geyser)

PhaseNeutralEarth

PhaseNeutralEarth

Red BlackGreen

PhaseNeutralEarth

3/203/201/18

7/207/201/18

3/0.9143/0.9141/1.120

7/0.9147/0.9141/1.120

Internal wiring

S.B. to Individual points Off/ return

__point__

Neutral

Yellow

Black

1/18

1/18

1/1.120

1/1.120

Purpose From/To Electric supply

Colour of wire

Wire type with gaug

e

Size of wire (mm)

Recommended sizes & colours of wires(A) For Single Phase Supply (load upto 3 KW)

Note: S.B.-Switch board D.B.- Distribution board A.C.- Air conditioner

Mains

Circuits or

Sub-

mains

Internal wiring

Meter cabinet to D.B. in flat

D.B. to room S.B.

D.B. to kitchen power point

D.B. to bath room (for geyser)

D.B. to bedroom A.C.

S.B. to individual points

PhasePhasePhaseNeutralEarth

Red (R) Yellow (Y)Blue (B)

BlackGreen

7/207/207/207/203/20

7/0.9147/0.9147/0.9147/0.9143/0.914

PhaseNeutralEarth

R/Y/BBlackGreen

3/203/201/18

3/0.9143/0.9141/1.120

PhaseNeutralEarth

R/Y/BBlackGreen

3/203/201/18

3/0.9143/0.9141/1.120

PhaseNeutralEarth

R/Y/BBlackGreen

7/207/201/18

7/0.9147/0.9141/1.120

PhaseNeutralEarth

R/Y/BBlackGreen

7/207/201/18

7/0.9147/0.9141/1.120

Off/return__point__

Neutral

Yellow

Black

1/18

1/18

1/1.120

1/1.120

Recommended sizes & colours of wires(A) For Three Phase Supply (load upto 10 KW)

Purpose From/To Electric supply

Colour of wire

Wire type with

gauge

Size of wire (mm)

Note: S.B.-Switch board D.B.- Distribution board A.C.- Air conditioner

_________________________________________________Sheathing of a wire / cable:

Sheathing is basically something that wraps around or surrounds something. It is the outer protective covering of plastic, or such material which provides insulation to the enclosed wires or cables carrying the electricity.

Shielding:

• It consists of an arrangement of metal mesh or plates designed to protect electronic equipment from ambient electromagnetic interference. • It can be the protective cable covering that eliminates electromagnetic & radio frequency interference. • It is the separation of metallic parts by an electrical nonconductor; insulated by other than an air gap.• The shielding effect describes the decrease in attraction between an electron and the nucleus in any atom with more than one electron shell. It is also referred to as the screening effect or atomic shielding.

Metal Blank Cover Plate

Wires Connected Together in a Junction Box

A Junction Box With Wires A Junction Box

JUNCTION BOX

MAKE ALL CONNECTIONS IN APPROVED BOXES •Always remember that connections must be made in an approved box. Never connect one cable to another by an open-line splice.

•All switch, outlet, and junction boxes must be positioned so they are always accessible.

•You can easily remove knockout plugs with a nail punch, screwdriver or metal rod.

Plugs, Sockets & Switches:

Socket: • A receptacle that receives a plug • A device into which an electric plug can be inserted in order to make a connection in a circuit•It is such a device mounted on a wall and connected to the electricity supply •A device designed to provide electric connections and mechanical support for an electronic or electric component requiring convenient replacement.• Wall sockets (sometimes also known as power points, power sockets, electric receptacles, or electrical outlets) are female electrical connectors that have slots or holes which accept and deliver current to the prongs of inserted plugs. To reduce the risk of injury or death by electric shock, some plug and socket systems incorporate various safety features. Sockets are designed to accept only matching plugs and reject all others.

Plug:

An electric plug is a male electrical connector with contact prongs to connect mechanically and electrically to slots in the matching female socket. They may also be lamp holder plugs.

Switches:•A device used to break or open an electric circuit or to divert current from one conductor to another. •In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another

Switch boards:An electric switchboard is a device that directs electricity from one source to another. It is an assembly of panels, each of which contain switches that allow electricity to be redirected. The operator is protected from electrocution by safety switches and fuses. The amount of power going into a switchboard must always equal to the power going out to the loads. Inside the switchboard there is a bank of bus bars - generally wide strips of copper to which the switchgear is connected. These act to allow the flow of large currents through the switchboard, and are generally bare and supported by insulators.

Remote controlled switch board

CONNECT NEW WIRING TO LAST OUTLET IN CABLE  •New wiring should be connected to the last outlet in a run of cable. To locate the last outlet in the run, shut off the current. Remove the cover plates from each outlet on the circuit. The last outlet in the run has wires connected to only two of the four terminal screws.

•The two unused terminal screws on the last receptacle serve as a starting point for wiring to a new outlet.

TYPES OF INSTALLING WIRING:

• OPEN / EXPOSED WIRING• CONDUIT WIRING• CONCEALED WIRING• CASING & CAPPING

Open wiring or surface mounted wiring:

Surface mounted wiring runs on the outside of the wall instead of grooves made in the wall. For this wire moulds (casing & capping) are used to connect to the boxes helps concealing the wire & protecting it. Wire moulds come in either plastic or metal form and varies in depth & thickness according to the installation. Wire is fed from box to box through wire mould raceways that protect it. Plastic moulds are better to install and durable. Earlier, Wood Casing Wiring and/or Batten Wiring Method were used.

Conduit wiring:Electrical conduit is metal or plastic pipe through which electrical wires are run. This conduit protects the wires and is usually used in exposed locations, such as along the outer surface of a wall. Each type of electrical conduit has its own maximum no. of electrical wires allowed in the circuit and their fill sizes may differ in spite of similar sizes.• Rigid conduits• PVC is a plastic conduit that is often used for underground installations and in wet areas. • EMT conduit is a metal thin walled conduit that comes in ten foot lengths. • Flexible conduit (armor-clad) is normally made of twisted metal and is very flexible and can be formed around corners and other obstacles.

Rigid conduits

Non-Metallic Sheathed Wire (NM):This wire, commonly called Romex, is a plastic coated wire that has either two or three conductors and a bare ground wire. This is the typical wiring used in most homes. The rating for this wire is either 15 amps, 20 amps, or 30 amps, depending on the installation.Single Strand Wire:Single strand wire is insulated and many of these can be pulled into the same pipe.

Concealed wiring:

Concealed means to keep from being seen, found, observed, or discovered; hide. The wiring is done in such a way that they are not seen on the surface.

They are concealed in the following ways as per the requirement:• Grooves are made in the wall and then the wiring is placed and the wall is plastered & painted from above• Wiring is carried through false ceiling• Wiring is carried through the false flooring• The wire may also be run through hidden electrical ducts• All the wire may pass through the partitions and/or panelling• Proper junction box for repair, maintenance and addition of new connections are given

Concealed wiring:

There are few advantages of the concealed wiring: • It is quite effective in avoiding the electric shocks. • They look good aesthetically, for the electric wires are not exposed.• Avoid spread of fire in case of accidents• The wires are protected from wearing/deterioration/rodents or careless damage.

Concealed wiring is safe for the building as long as it is properly placed and joints are properly covered. There should be tap holes for checking the wiring at suitable intervals. The wiring should not be too close to the slab and also from the water bodies in the building. The wiring should not be exposed to external cracks in the walls. The concealed wiring will not weaken the concrete structure.

Care to be taken while installing concealed wiring:

• The wrong size or type of wire should not be used• The wiring should be handled under proper supervision so as to avoid damage due to rough handling during installation• The cable might should be properly protected or secured.• Follow wiring standards and proper joining• Proper grounding of wires• Properly insulated wires• Study of the structural features / construction before installing, (type of wall, material, etc.)• Skilled & qualified technicians• Proper electrical diagram with planned future needs• Proper inspection points wherever necessary

Casing & Capping:

It is a method of extending an insulated wire through an opening that includes casing. The capping has radially inward surfaces and a defining aperture. The casing is placed onto the surface with screws and the insulated wire is passed through the aperture. In case the insulated wire touches the cap, the insulated wire will remain undamaged by the smooth top and radially inward surfaces. The capping covers the wires and can be painted to suit the interiors and it well-fits onto the casing below. The advantage of this method is that it is easy to install, repair, remove and if the need be extend or detach and replace.

Important Indications for house wiring:

• House wire: PVC material• Conductor material: High purity, Oxygen free Copper• Application: Construction/ computer• Type: Low voltage• Insulation material and/or sheathing: PVC• Jacket: PVC• Colours used: Yellow, blue, red, black, green, brown, etc.• Twist type: Multi twist, rope lay; Seven twist; Solid• No. of cores: single to 5 no. of cores• Type of wire/cable: Flexible/ power/ soft/ electrical/ flexible power/ flat• Nominal voltage• Thickness, Diameter, Weight & Insulation thickness

What is a FUSE?

In electronics and electrical engineering a fuse (from the Latin "fusus" meaning to melt) is a type of sacrificial overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows, which interrupts the circuit in which it is connected. Short circuit, overload or device failure is often the reason for excessive current.A fuse interrupts excessive current (blows) so that further damage by overheating or fire is prevented. Wiring regulations often define a maximum fuse current rating for particular circuits. Over current protection devices are essential in electrical systems to limit threats to human life and property damage. Fuses are selected to allow passage of normal current and of excessive current only for short periods.

A Circuit Breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switch gear designed to protect high voltage circuits feeding an entire city.

Low voltage circuit breakers -

Low voltage (less than 1000 VAC) types are common in domestic, commercial and industrial application, include:• MCB (Miniature Circuit Breaker)—rated current not more than 100 A. Trip characteristics normally not adjustable. Thermal or thermal-magnetic operation. •MCCB (Molded Case Circuit Breaker)—rated current up to 1000 A. Thermal or thermal-magnetic operation. Trip current may be adjustable in larger ratings. • Low voltage power circuit breakers can be mounted in multi-tiers in LV switchboards or switchgear cabinets.

MCB is a magnetic tripping device working during short circuit or overloading. It is mainly used to protect life and other electrical assets. Small circuit breakers are either installed directly in equipment, or are arranged in a breaker panel.

________________________________________________Residual Current Devices, also known as ground-fault circuit interrupters and appliance leakage current interrupters, are used to detect ground faults - leakage of current to someplace other than the neutral and live wires (like the ground wire or a person). When a ground fault is detected, the device quickly cuts off the circuit.

NON CONVENTIONAL SOURCES

Solar and Wind energy sources