gile

1. 1
A
TRAINING REPORT
ON
ESSKY ENTERPRISES PVT.LTD.
SUBMITTED TO STATE BOARD OF TECHNICAL EDUCATION,
PANCHKULA
IN PARTIAL FULFILMENT FOR THE AWARD OF DIPLOMA
IN
ELECTRICAL ENGINEERING
(2015-2018)
SUMMITTED TO:- SUMMITTED BY:-
MR. NITIN SAURABH VATS
LECT. IN EE DEPT. ROLL NO:-15020090026
EE 5TH
SEM
P.D.M.POLYTECHNIC, SARAI AURANGABAD
(BAHADURGARH)

2. 2
PREFACE
This project report is completely guide to the “ESSKY
ENTERPRISES PVT.LTD” according to the need our syllabus
prescribed by STATE BOARD OF TECHNICAL EDUCATION,
PANCHKULA. For the project the matter has been discussed
pricewise. Every topic has been explained in sample way, so that
everyone understands this easily and a great care has been taken to
frame all the topics. So that no position regarding to this has been let
out. Although everyone has been taken while preparing this report but
the possibilities finding and error cannot be ruled out. Suggestion for
future improvement will be thankfully acknowledged and implemented.

3. 3
CERTIFICATE
This Is Certify that this project entitles “ESSKY ENTERPRISES
PVT.LTD” IS combined work of the following students:-
SAURABH VATS 15020090026
It is submitted in partial FULFILMENT FOR THE AWARD OF
DIPLOMA in electrical engineering state Board Of Technical
Education, Panchkula is a record of the student own workcarried and
completely by them under my guidance and supervisor .
Mr. Nitin
Lect.(Electrical Dept.)
PDM POLYTECHNIC, BAHADURGARH
Signature
Mr. Kiran Kumar
H.O.D. (Electrical DEPT.)

4. 4
ACKNOWLEDGEMENT
It affords me great pleasure, my gratitude towards my esteemed and
guide MR. NITIN (faculty of ELECTRICAL ENGINEERING, P D
M POLYTECHNIC, BAHADURGARH ) for giving us the
opportunity to work on this project and helping us through-out with is
guidance and suggestions.
My special thanks to guide MR. KIRAN KUMAR (H.O.D.
OF ELECTRICAL DEPT.), P.D.M. POLYTECHNIC,
BAHADURGARH for his patronage and blessing.
SAURABH VATS 15020090026

5. 5
INDEX
 INTRODUCTION 1-10
 COMPANY PROFILE 11-13
 HISTORY 14
 DATA 15-16
 WIRING SAFETY CODES 17-18
 COLOUR CODE 19
 WIRING METHODS 20-24
 CABLES 25-28
 ALUMINIUM CONDUCTORS 29-32

6. 6
INTRODUCTION
Wire electrical discharge machining is a specialized thermal machining process capable of
accurately machining parts with varying hardness or complex shapes, which have sharp edges
that are very difficult to be machined by the main stream machining processes. This practical
technology of the WEDM process is based on the conventional EDM sparking phenomenon
utilizing the widely accepted non –contact technique of material removal. Since the introduction
of the process, WEDM has evolved from a simple means of making tools and dies to the best
alternative of producing micro-scale parts with the highest degree of dimensional accuracy and
surface finish quality.
Wire electrical discharge machining (WEDM) is a non traditional, thermoelectric process which
erodes material from the work piece by a series of discrete sparks between a work and tool
electrode immersed in a liquid dielectric medium. These electrical discharges melt and vaporize
minute amount of work material, which are then ejected and flushed away by dielectric. A wire
EDM spark discharges between a small wire electrode (usually less than 0.5mm diameter) and a
work piece with deionised water as the dielectric medium and erodes the work piece to produce
complex two and three dimensional shapes according to a numerically controlled path.
Wire electrical discharge is a widely accepted non –traditional material removal process used
to manufacture components with intricate shapes and profiles. It is a considered as a unique
adaptation of the conventional EDM process, which uses an electrode to initialize the sparking
process. However ,WEDM utilizes a diameter 0.05-0.3mm, capable of achieving very small
corner radii.The wire is kept in tension using a mechanical tensioning device reducing the
tendency of producing inaccurate parts. During the WEDM process, the material is eroded
ahead of the wire and there is no direct contact between the work piece and the wire eliminating
the mechanical stresses during machining. In addition, the WEDM process is able to machine
exotic and high strength and temperature resistant ( HSTR ) materials and eliminate the
geometrical changes occurring in the machining of heat treated steels .WEDM was first
introduced to the manufacturing industry in the late 1960s . The development of the process was
the result of seeking a technique to replace the machined electrode used in EDM in 1974.
Wire –electro discharge machining has been defined as the process of material remIoval of
electrically conductive materials using the thermo-electric source of sparks between electrodes
of wire cut EDM machine.

7. 7
The electrode is a thin wire and it is pulled through the work piece from a supply spool on to a
take up mechanism. On application of a suitable voltage, discharge occurs between the wire
electrode and the work piece in the presence of a flood of deionised water of high insulating
resistance.

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1.1BASIC PRINCIPLE OF WEDM
WEDM is one of the most extended non conventional machining process. It Is widely used to
machine dies and molds aimed at producing components for many industries. The main
advantage of WEDM is its capability for the production of high complexity shapes with a high
degree of accuracy, independently of the mechanical properties of the material (especially,
hardness, brittleness and resistance ). WEDM is based on the material removal through a series
of electrical discharges applied between two electrically conductive. Dielectric fluid is injected
into the gap, which is the space between the electrodes. Thus , there is no contact between tool
and work piece during the process.Each discharge is generated as follows: the WEDM machine
power supply applies a voltage between work piece and wire.It starts the ionization period of
the dielectric fluid, which is known as ignition time delay. Dielectric ionization induces the
discharge that vaporizes all the material around. Before applying the voltage for the next
discharge, the dielectric cools the gap and removes the erosion debris during a period of time
knows as off time .A servo control is used to control the gap size. Most of servo control
systems take the discharge voltage as the feedback signal. On the other hand, the wire is
continuously running at constant speed. The figure below shows an image of WEDM
process.Wire breakage and unstable machining are two of the most important aspects of the
WEDM process due to their detrimental effects, such a reduction of machining performance
and surface damage.

9. 9
Different factors can lead to wire breakage such as generation of short circuits, inefficient
removal of erosion debris as well as other types of stochastic phenomenon that appears during
the cutting process. Usually, if an abnormal situation is detected, the machine operator
manually adjusts the parameters of the machine using his/her own experience. Moreover,
WEDM machines work most of the time without operator assistance. Therefore, it would be
desirable to predict wire breakage and unstable machining in order to on-time re-adjust the
machine parameters.
The WEDM machine tool comprises of main work table (X-Y) on which the work piece is
clamped, an auxiliary table (U-V ) and wire drive mechanism.The main table moves along X
and Y –axis .the traveling wire, made generally of brass, is continuously fed from wire spool
and collected from take up spool, it moves through the work piece and is supported under
tension between a pair of wire guides located at the opposite sides of the work piece ,the lower
wire guide is stationary rare as the upper wire guide, supported by UV table can be displaced
transversly,along U & V axis with respect to lower wire guide. The upper wire guide can also
be positioned vertically along z axis by moving the quill.
As the process proceeds, the X-Y controller displaces the work piece transversely and the
driver along a pre determined path programmed in controller, while the machine operation is
continuous, machining zone is continuously flushed with water passing thru the nozzle on the
both side of work piece. Since water is used as dielectric medium, it is very important that
water doesn’t ionize.

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1.2 WEDM PROCESS
The material removal mechanism of WEDM is very similar to the conventional EDM process
involving the erosion effect produced by the electrical discharges ( sparks ) . in WEDM ,
material is eroded from the work piece by a series of discrete sparks occurring between the
work piece and the wire separated by a stream of dielectric fluid , which is continuously fed to
the machining zone. However , todays WEDM process is commonly conducted on work pieces
that are totally submersed in a tank filled with dielectric fluid. Such a submersed method of
WEDM promotes temperature stabilization and efficient flushing especially in cases where the
work piece has varying thickness. The WEDM process makes use of electrical energy
generating a channel of plasma between cathode and anode, and turns it into thermal energy at
temperature in the range of 8000-12000*C or as high as 20000*C –initializing a substantial
amount of heating and melting of material on the surface of each pole. When the pulsating direct
current power supply occurring between 20000 and 30000Hz is turned off, the plasma channel
breaks down. This causes a sudden reduction in temperature allowing the circulating dielectric
fluid to implore the plasma channel and flush the molten particles from the pole surfaces in the
form of microscopic debris. While the material removal mechanism of EDM and WEDM are
similar , their functional characteristics are not identical . WEDM uses a thin wire continuously
feeding through the work piece by a microprocessor, which enables parts of complex shapes to
be machined with exceptional high accuracy. A varying degree of taper ranging from 15* for a
100mm thick to 30* for a 400mm thick work piece can also be obtained on the cut surface. The
microprocessor also constantly maintains the gap between the wire and work piece ,which varies
from 0.025 to 0.05 mm . WEDM eliminates the need for elaborates pre shaped electrodes.
Which are commonly required in EDM to perform the roughing and finishing operations. In the

11. 11
case of WEDM , the wire has to make several machining passes along the profile to be
machined to attain the required dimensional accuracy and surface finish quality. The typical
WEDM cutting rates are 300mm2/min for a 50mm thick D2 tool steel and 750mm2/min for
a150mm thick aluminium , and SF quality is as fine as 0.04 to 0.25micron.In addition ,WEDM
uses de-ionizer water instead of hydrocarbon oil as the di-electric fluid and contains it with in
the sparking zone.The de-ionized water is not suitable for conventional EDM as it causes rapid
electrode wear,but its low viscosity and rapid cooling rate make it ideal for WEDM.
1.3 HYBRID MACHINING PROCESS
There are a no of hybrid machining process seeking the combined advantages of WEDM with
other machining techniques . one such combination is wire electrical discharge grinding, which
is commonly used for the micro –machining of fine rods utilized in the electronic circuitry.
WEDM employs a single wire guide to confine the wire tension within the discharge area
between the rod and the front edge of wire and to minimize the wire vibration. Therefore,it is
possible to grind a rod that is as small as 5mm diameter with high accuracy,good repeatability
and satisfactory straightness. Other advantages of WEDM include the ability to machine a rod
with a large aspect ratio, maintaining the concentricity of the rod and providing a wider choice
of a complex shapes such as tapered and stepped shapes at various sections.WEDM process in
the micro machining of fine electrodes or pins with a large aspect ratio. Which are difficult to be
machined by traditional precision micro machining methods such as micro EDM ,exciter laser
drilling. Some of the HMPs seek to improve the WEDM performance measures such as the
surface integrity and the CR. For example, the ultrasonic vibration is applied to the wire
electrode to improve the SF quality together with the CR and to reduce the residual stress on the
machined surface. On the other hand,the wire electrochemical grinding process replaces the

12. 12
electrical discharge used in WEDM with an electrochemical solution to produce high SF quality
part for a wide range of machining conditions. The SF quality obtained from the WECG is
suitable for finishing micro parts.A rotary axis is also added to WEDM to achieve higher cutting
speed (CS ) and to unable the generation of free from cylindrical geometries. The effects of the
various process parameters such as part rotational speed,wire feed rate and pulse on-time on the
surface integrity and roundness of part produced have been investigated in the same feasibility
study.
1.4 WIRE-EDM EQUIPMENT
A wire equipment machine consists of four sub systems : the position system,the wire
drivesystem,the power supply, and dielectric system. All the four sub-systems are distinct from
conventional EDM.
1.4.1 POSITION SYSTEM
Wire –EDM positioning system usually consists of CNC two axis wire positioning system. The
most unique feature of the CNC system is that it must operates in adaptive control mode to
always ensure the consistency of the gap between the wire and the work piece. If the wire
should come in contact with the work piece or if a small piece of material bridges the gap and
causes a short circuit, positioning system must sense this condition and backup along the
programmed path to re –establish the proper cutting conditions.

13. 13
1.4.2 WIRE DRIVE SYSTEM
The function of the wire drive system is to continuously deliver fresh wire under constant
tension to the work area. The need for constant wire tension is important to avoid such
problems as tapered , machining streaks, wire breaks, and vibration marks.As the drive passes
thru work piece , it is guided by a sphere of diamond guides. Before being collected by the take
up spool, it passes thru the series of tensioning rollers.
1.4.3 POWER SUPPLY
The most pronounced differences between the power supplies used for WEDM And
conventional EDM are frequency of pulse used and the current. To produce the smoothest
possible surface finish possible, pulse frequencies as high as 1MHz may be used with wire
EDM. Such high frequency ensure that each spark removes as little material as possible, thus
reducing the size of EDM crater. Because diameter of wire used is small , its carrying
capability Is limited. Because of this limitation, WEDM power supplies are really built to
deliver more than 20 Amps of current.
1.4.4. DIELECTRIC SYSTEM
De-ionized water is the di-electric used for the WEDM processes. Deionized water is used for
four reasons: low viscosity, high cooling rate, high material removal rate and absence of fire
hazard.The small cutting gap used with the WEDM mandates that a low velocity dielectric be
used to ensure adequate flushing. Water meets this criterion. Water can also remove heat from
the cutting areas much more efficiently than conventional dielectric oils. More efficient cooling
results in extremely thin recast layers.Finally , because of slow processing speed of WEDM ,
many users run their most time consuming jobs over night or over the weekend unattended.
With conventional EDM , the use flammable dielectric oils present a fire hazard. When using
water for dielectric , the fire hazard problem is eliminated.
1.5 ADVANTAGE OF WIRE –EDM PROCESSES:
* No electrode fabrication required
* No cutting forces
*Unmanned machining
*Die cost reduced by 30-70%
*Cuts hardened material
*Intricate shapes can be cut easily
*Very small kerfs width

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1.6 DISADVANTAGES
* High capital cost
* Recast layer
* Electrolysis can occur in some materials
* Slow cutting rates
* Not applicable to very large work piece
1.7 WEDM APPLICATIONS:
*The process is ideal for stamping die components. It is often possible to fabricate punch as
well in same cut.
* Other tools and parts with intricate outline shapes, such as lathe form tools, extrusion dies,
flat templates and almost any complicated shapes can be produced.
*It has been extensively used for machining of exotic materials used in aero-space industries,
refractory metals, and hard carbide and hardened steel.

15. 15
COMPANY PROFILE
HOUSE WIRING
Esskay Enterprises Pvt.ltd. is a Private incorporated on 19 May 1993. It is classified
as Non-govt company and is registered at Registrar of Companies, Mumbai. Its
authorized share capital is Rs. 1,000,000 and its paid up capital is Rs. 0.It is inolved
in Other wholesale [Includes specialized wholesale not covered in any one of the
previous categories and wholesale in a variety of goods without any particular
specialization.] Esskay Enterprises Pvt.ltd.'s Annual General Meeting (AGM) was
last held on N/A and as per records from Ministry of Corporate Affairs (MCA), its
balance sheet was last filed on N/A.
Esskay Enterprises Pvt.ltd.'s Corporate Identification Number is (CIN)
U51900MH1993PTC072053 and its registration number is 72053.Its Email address
is and its registered address is 507,SAHAKR BHAVAN,640/48, NARSI NATHA
STREET, MUMBAI MUMBAI-9 MH 000000 IN ,
Esskay Enterprises, an ISO 9001:2008 certified company, are one of the leading
manufacturers and fabricators of industrial pressure vessels, process equipments,
heat exchangers in carbon steel, stainless steel, alloy steel aluminium, copper and
other alloy metals Catering to the industrial requirement in various industries like
paper, Parma, dairy, breweries, chemicals, petrochemical, Heavy engineering by
using superior engineering techniques and modern technology in fabrication and
machining our experience allows us to handle projects and complete successfully In
a stipulated time including repairing and other activities.
Our company was established in 2004 with qualified professionally technicians and
Engineers we have a Huge client list of various fields. Our company is located in a
well developed industrial Area well connected by road, rail, and Air we have
facilities of modernized developed fabrication shop floor with attached machine
shop area 10000 sq ft with EOT crane SWL 8 Ton IN Unit I.

16. 16
We are to expand our works with the Unit II with the area of 12000 sq ft in the
coming year with modern machineries.
Homes typically have several kinds of home wiring for lighting and power distribution,
permanently installed and portable appliances, telephone, heating or ventilation system
control, and increasingly for home theatre and computer networks. [1] Regulations for
wiring installation vary widely around the world, with national, regional, and municipal
rules sometimes in effect. Some places allow the homeowner to install some or all of the
wiring in a home; other jurisdictions require that licensed electricians only install wiring.
History
Home wiring started when electric lights and telephone were first installed in homes
towards the end of the 19th century. By the end of the 20th century an increased variety
of systems were available for installation in homes. Electrical service is considered
essential in modern homes, but most new homes will also have provision for telephone,
Internet access, security, and television systems and others.
Typical features[edit]

17. 17
Single-phase ~230V/40A/9kW fuse box for apartment rewiring. Each appliance and each
room are highlighted into autonomous circuits - all in all this apartment has 14 individual
circuits. Relay is used for driving the light fixtures in large room.
In new home construction, wiring for all electrical services can be easily installed before
the walls are finished. In existing buildings, installation of a new system such as a
security system, or home theatre, may require additional effort to install concealed
wiring. Multiple unit dwellings such as condominiums and apartment houses may have
additional installation complexity in distributing services within a house.
Services commonly found include:
 Power points (wall outlets)
 Light fixtures and switches
 Telephone
 Internet
 Television, either broadcast, cable, or satellite
High-end features might include:
 Home theater
 Distributed audio
 Security monitoring
 Security CCTV
 Automation
 Energy management
Power and telecommunication services generally require entry points into the
home and a location for connection equipment. For electric power supply, a cable
is run either overhead or underground into a distribution board in the home. A
distribution board, or circuit breaker panel, is typically a metal box mounted on a
wall of the home. In many new homes the location of the electrical switchboard is
on the outside of the external wall of the garage.
How services are connected will vary depending on the service provider and
location of the home.

18. 18
HISTORY
Elements
Power point
Power points (receptacles, plugs, wallsockets) need to be installed throughout the
house in locations where power will be required. In many areas the installation
must be done in compliance with standards and by a licensed or qualified
electrician. Power points are typically located where there will be an appliance
installed such as, telephone, computers, television, home theater, security system,
CCTV system.
Light fittings and switches
The number of light fitting does depend on the type of light fitting and the
lighting requirements in each room. The incandescent bulb made household
lighting practical, but modern homes use a wide variety of light sources to
provide desired light levels with higher energy efficiency than incandescent
lamps. A lighting designer can provide specific recommendations for lighting in a
home. Layout of lighting in the home must consider control of lighting since this
affects the wiring. For example, multiway switching is useful for corridors and
stairwells so that a light can be turned on and off from two locations. Outdoor
yard lighting, and lighting for outbuildings such as garages may use switches
inside the home.
Telephone
Telephone wiring is required between the telephone company's service entrance
and locations throughout the home. Often a home will have telephone outlets in
the kitchen, study, living room or bedrooms for convenience. Telephone
company regulations may limit the total number of telephones that can be in use
at one time. The telephone cabling typically uses two pair twisted
cable terminated onto a telephone plug. The cabling is typically installed as a
daisy chain starting from the point where the telephone company connects to the
home or outlets may each be wired back to the entrance.

19. 19
DATA
Data wiring has two components, these are:
1. Data service delivery
2. Data network cable
The three most common ways data services are delivered to the home:
1. ADSL service on the back of the telephone cabling
2. Cable Modem
3. Fiber
ADSL service
ADSL services are typically delivered using the telephone cabling. An ADSL
modem needs a filter to segregate voice handsets from the ADSL modem.
Cable Modem cable modems are typically installed in location where there is an
existing Pay TV service outlet. The installation requires the installation of a Pay
TV outlet (F connector).
Fiber Fiber is the least common but it is growing in numbers. If the home has
fiber to it then the fiber terminates on what is known as an Optical Network
Termination unit (ONT) and it has a data port on it. Cabling from the street to the
point where the ONT is installed is fiber and is typically installed by the service
provider.
In all three cases the equipment supplied by the Internet provider will have a
connection to the computers installed in the building. This is the data network
cabling or LAN cabling.
If more than one computer or device (PC, printers, TV etc.) is to be connected in
the home, LAN cabling will be required. The cabling used for data networking is
similar to the phone cabling as it is twisted pair but of a much higher quality. The
cable is known as Category (Cat) 5 or Cat 6. The cabling must be installed as a
star wired configuration, that is the cabling runs from the point next to the
modem, hub, or router uninterrupted up to the outlet next to the device that needs

20. 20
to be connected. Computer network wiring cannot be chained from one outlet to
the next; each outlet is wired individually back to the hub or router next to the
modem. If only one computer is required,it can be directly plugged into the
modem. An alternative to a wired LAN especially useful for mobile devices is a
wireless LAN, which can reduce or eliminate all the fixed wiring.
Television
Cabling for free to air TV requires the following:
1. An antenna
2. Coaxial cable
3. TV outlets
Antenna types vary depending on location; an urban area with nearby transmitters
will require a smaller antenna than a rural site with distant stations. The antenna
is often mounted outdoors on the roof or a tower. A coaxial or twinlead cable is
run from the antenna to the location where the television is located. One common
type of cable is designated RG-6 Tri-shield or quad-shield cable. The cable is
terminated on a television outlets, typically an F connector mounted on a face
plate. If there are multiple outlets, an RF splitter is used to divide the signal
among them; outlets on the splitter are connected to television outlets at each
location (living room, rec room, bedrooms, den, for example). RF splitters come
with different types; some include amplifiers for multiple outlets.
Whilst most TV outlets use the F connector the Television or digital set top box
usually come with a connector known as Belling Lee so the cable used to connect
from the TV outlet to the television will need to have an F connector in one end
and a Belling Lee connector at the other end.
The distribution of pay TV through the home uses the same type of cabling used
for Free to Air TV with some variations. The variations are:
1. There is no antenna as there is either a satellite dish or a cable from the
street.
2. The cabling must be RG-6 quad shield.

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WIRING SAFETY CODES
Main article: Electrical codes
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.
First 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.

22. 22
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.

23. 23
COLOUR CODE
Colour-coded wires in a flexible plastic electrical conduit found commonly in modern
European houses
To enable wires to be easily and safely identified, all common wiring safety codes
mandate a colour scheme for the insulation on power conductors. In a typical electrical
code, some colour-coding is mandatory, while some may be optional. Many local rules
and exceptions exist per country, state or region.[1] Older installations vary in colour
codes, and colours may fade with insulation exposure to heat, light and ageing.
As of March 2011, the European Committee for Electrotechnical Standardization
(CENELEC) requires the use of green/yellow colour cables as protective conductors,
blue as neutral conductors and brown as single-phase conductors.[2]The United
States National Electrical Code requires a green or green/yellow protective conductor, a
white or grey neutral, and a black single phase.[3]
The United Kingdom requires the use of wire covered with green insulation, to be
marked with a prominent yellow stripe, for safe earthing (grounding) connections.[4] This
growing international standard was adopted for its distinctive appearance, to reduce the
likelihood of dangerous confusion of safety earthing (grounding) wires with other
electrical functions, especially by persons affected by red-green colour blindness.

24. 24
WIRING METHODS
Installing electrical wiring by "chasing" grooves into the masonry structure of the walls
of a building
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.
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 equipment in hazardous
areas.
Wires and cables are rated by the circuit voltage, temperature rating and environmental
conditions (moisture, sunlight, oil, chemicals) in which they can be used. A wire or cable

25. 25
has a voltage (to neutral) rating and a maximum conductor surface temperature rating.
The amount of current a cable or wire can safely carry depends on the installation
conditions.
EARLY WIRING METHODS
The first interior power wiring systems used conductors that were bare or covered with
cloth, which were secured by staples to the framing of the building or on running boards.
Where conductors went through walls, they were protected with cloth tape. Splices were
done similarly to telegraph connections, and soldered for security. Underground
conductors were insulated with wrappings of cloth tape soaked in pitch, and laid in
wooden troughs which were then buried. Such wiring systems were unsatisfactory
because of the danger of electrocution and fire, plus the high labour cost for such
installations.
Knob and tube[edit]
Main article: Knob and tube wiring
Knob-and-tube wiring (the orange cable is an unrelated extension cord)
The earliest standardised method of wiring in buildings, in common use in North
America from about 1880 to the 1930s, was knob and tube (K&T) wiring: single
conductors were run through cavities between the structural members in walls and
ceilings, with ceramic tubes forming protective channels through joists and ceramic
knobs attached to the structural members to provide air between the wire and the lumber
and to support the wires. Since air was free to circulate over the wires, smaller
conductors could be used than required in cables. By arranging wires on opposite sides
of building structural members, some protection was afforded against short-circuits that
can be caused by driving a nail into both conductors simultaneously.

26. 26
By the 1940s, the labour cost of installing two conductors rather than one cable resulted
in a decline in new knob-and-tube installations. However, the US code still allows new
K&T wiring installations in special situations (some rural and industrial applications).
METAL-SHEATHED WIRES
Lead cased electrical wire from a circa 1912 house in Southern England. Two
conductors are sheathed in red and black rubber, the central earth wire is bare. These
wires are dangerous because the sheath is prone to split if repeatedly flexed.
In the United Kingdom, an early form of insulated cable,[7] introduced in 1896, consisted
of two impregnated-paper-insulated conductors in an overall lead sheath. Joints were
soldered, and special fittings were used for lamp holders and switches. These cables
were similar to underground telegraph and telephone cables of the time. Paper-insulated
cables proved unsuitable for interior wiring installations because very careful
workmanship was required on the lead sheaths to ensure moisture did not affect the
insulation.
A system later invented in the UK in 1908 employed vulcanised-rubber insulated wire
enclosed in a strip metal sheath. The metal sheath was bonded to each metal wiring
device to ensure earthing continuity.
A system developed in Germany called "Kuhlo wire" used one, two, or three rubber-
insulated wires in a brass or lead-coated iron sheet tube, with a crimped seam. The

27. 27
enclosure could also be used as a return conductor. Kuhlo wire could be run exposed on
surfaces and painted, or embedded in plaster. Special outlet and junction boxes were
made for lamps and switches, made either of porcelain or sheet steel. The crimped seam
was not considered as watertight as the Stannos wire used in England, which had a
soldered sheath.[8]
A somewhat similar system called "concentric wiring" was introduced in the United
States around 1905. In this system, an insulated electrical wire was wrapped with copper
tape which was then soldered, forming the grounded (return) conductor of the wiring
system. The bare metal sheath, at earth potential, was considered safe to touch. While
companies such as General Electric manufactured fittings for the system and a few
buildings were wired with it, it was never adopted into the US National Electrical Code.
Drawbacks of the system were that special fittings were required, and that any defect in
the connection of the sheath would result in the sheath becoming energised.[9]
Other historical wiring methods[edit]
Other methods of securing wiring that are now obsolete include:
 Re-use of existing gas pipes when converting gas light installations to electric
lighting. Insulated conductors were pulled through the pipes that had formerly
supplied the gas lamps. Although used occasionally, this method risked insulation
damage from sharp edges inside the pipe at each joint.
 Wood mouldings with grooves cut for single conductor wires, covered by a wooden
cap strip. These were prohibited in North American electrical codes by 1928.
Wooden moulding was also used to some degree in England, but was never permitted
by German and Austrian rules.[10]
 A system of flexible twin cords supported by glass or porcelain buttons was used
near the turn of the 20th century in Europe, but was soon replaced by other
methods.[11]
 During the first years of the 20th century, various patented forms of wiring system
such as Bergman and Peschel tubing were used to protect wiring; these used very
thin fiber tubes, or metal tubes which were also used as return conductors.[12]

28. 28
 In Austria, wires were concealed by embedding a rubber tube in a groove in the
wall, plastering over it, then removing the tube and pulling wires through the
cavity.[13]
Metal moulding systems, with a flattened oval section consisting of a base strip and a
snap-on cap channel, were more costly than open wiring or wooden moulding, but could
be easily run on wall surfaces. Similar surface mounted raceway wiring systems are still
available today.

29. 29
CABLES
Main article: Power cable
Wiring for extremely wet conditions
Armoured cables with two rubber-insulated conductors in a flexible metal sheath were
used as early as 1906, and were considered at the time a better method than open knob-
and-tube wiring, although much more expensive.
The first rubber-insulated cables for building wiring were introduced in 1922 with US
patent 1458803, Burley, Harry & Rooney, Henry, "Insulated electric wire", issued 1923-
06-12, assigned to Boston Insulated Wire And Cable.[citation needed] These were two or more
solid copper electrical wires with rubber insulation, plus woven cotton cloth over each
conductor for protection of the insulation, with an overall woven jacket, usually
impregnated with tar as a protection from moisture. Waxed paper was used as a filler and
separator.
Over time, rubber-insulated cables become brittle because of exposure to atmospheric
oxygen, so they must be handled with care and are usually replaced during renovations.
When switches, socket outlets or light fixtures are replaced, the mere act of tightening
connections may cause hardened insulation to flake off the conductors. Rubber
insulation further inside the cable often is in better condition than the insulation exposed
at connections, due to reduced exposure to oxygen.

30. 30
The sulphur in vulcanised rubber insulation attacked bare copper wire so the conductors
were tinned to prevent this. The conductors reverted to being bare when rubber ceased to
be used.
Diagram of a simple electrical cable with three insulated conductors
About 1950, PVC insulation and jackets were introduced, especially for residential
wiring. About the same time, single conductors with a thinner PVC insulation and a thin
nylon jacket (e.g. US Type THN, THHN, etc.) became common.[citation needed]
The simplest form of cable has two insulated conductors twisted together to form a unit.
Such un-jacketed cables with two (or more) conductors are used only for extra low
voltage signal and control applications such as doorbell wiring.

31. 31
US single-phase residential power distribution transformer, showing the two insulated
"Line" conductors and the bare "Neutral" conductor (derived from the earthed center-tap
of the transformer). The distribution supporting centenaries are also shown.
In North American practice, an overhead cable from a transformer on a power pole to a
residential electrical service usually consists of three twisted (triplexed) conductors, with
one being a bare protective neutral/earth/ground conductor (which may be made of
copper), with the other two being the insulated conductors for both of the two 180 degree
out of phase 120 V line voltages normally supplied.[14] However, the earthed/grounded
conductor is often a catenary cable (made of steel wire), which is used to support the
insulated Line conductors. For additional safety, the ground conductor may be formed
into a stranded co-axial layer completely surrounding the phase/line conductors, so that
the outermost conductor is grounded.
Copper conductors
Main article: Copper wire and cable
Electrical devices often contain copper conductors because of their multiple beneficial
properties, including their high electrical conductivity, tensile
strength, ductility, creep resistance, corrosion resistance, thermal conductivity,coefficient

32. 32
of thermal expansion, solderability, resistance to electrical overloads, compatibility
with electrical insulators and ease of installation.
Despite competition from other materials, copper remains the preferred electrical
conductor in nearly all categories of electrical wiring.[15][16] For example, copper is used
to conduct electricity in high, medium and low voltagepower networks, including power
generation, power transmission, power
distribution, telecommunications, electronics circuitry, data
processing, instrumentation, appliances, entertainment systems, motors, transformers,
heavyindustrial machinery and countless other types of electrical equipment.[17]

33. 33
ALUMINIUM CONDUCTORS
Terminal blocks for joining aluminum and copper conductors. The terminal blocks may
be mounted on ADIN RAIL.
Aluminium wire was common in North American residential wiring from the late 1960s
to mid-1970s due to the rising cost of copper. Because of its greater resistivity,
aluminium wiring requires larger conductors than copper. For instance, instead of 14
AWG (American wire gauge) for most lighting circuits, aluminium wiring would be 12
AWG on a typical 15 ampere circuit, though local building codes may vary.
Aluminium conductors were originally indiscriminately used with wiring devices
intended for copper conductors. This practice was found to cause defective connections
unless the aluminium was one of a special alloy, or all devices — breakers, switches,
receptacles, splice connectors, wire nuts, etc. — were specially designed for the purpose.
These special designs address problems with junctions between dissimilar metals,
oxidation on metal surfaces and mechanical effects that occur as different metals expand
at different rates with increases in temperature.
Unlike copper, aluminium has a tendency to cold-flow under pressure, so screw clamped
connections may become loose over time. This can be mitigated by using spring-loaded
connectors that apply constant pressure, applying high pressure cold joints in splices and
termination fittings, or using a bolted mechanical type clamp wire connector and
tightening it to a specified torque.
Also unlike copper, aluminium forms an insulating oxide layer on the surface. This is
sometimes addressed by coating aluminium conductors with an antioxidant
paste (containing zinc dust in a low-residue polybutene base[18]) at joints, or by applying
a mechanical termination designed to break through the oxide layer during installation.

34. 34
Because of improper design and installation, some junctions to wiring devices would
overheat under heavy current load, and cause fires. Revised standards for wiring devices
(such as the CO/ALR "copper-aluminium-revised" designation) were developed to
reduce these problems. Nonetheless, aluminium wiring for residential use has acquired a
poor reputation and has fallen out of favour.
Aluminium conductors are still used for bulk power distribution and large feeder circuits,
because they cost less than copper wiring, and weigh less, especially in the large sizes
needed for heavy current loads. Aluminium conductors must be installed with
compatible connectors.
Modern wiring materials
Modern non-metallic sheathed cables, such as (US and Canadian) Types NMB and
NMC, consist of two to four wires covered with thermoplastic insulation, plus a bare
wire for grounding (bonding), surrounded by a flexible plastic jacket. Some versions
wrap the individual conductors in paper before the plastic jacket is applied.
Special versions of non-metallic sheathed cables, such as US Type UF, are designed for
direct underground burial (often with separate mechanical protection) or exterior use
where exposure to ultraviolet radiation (UV) is a possibility. These cables differ in
having a moisture-resistant construction, lacking paper or other absorbent fillers, and
being formulated for UV resistance.
Rubber-like synthetic polymer insulation is used in industrial cables and power cables
installed underground because of its superior moisture resistance.
Insulated cables are rated by their allowable operating voltage and their
maximum operating temperature at the conductor surface. A cable may carry multiple
usage ratings for applications, for example, one rating for dry installations and another
when exposed to moisture or oil.
Generally, single conductor building wire in small sizes is solid wire, since the wiring is
not required to be very flexible. Building wire conductors larger than 10 AWG (or about
6 mm²) are stranded for flexibility during installation, but are not sufficiently pliable to
use as appliance cord.

35. 35
Cables for industrial, commercial and apartment buildings may contain many insulated
conductors in an overall jacket, with helical tape steel or aluminium armour, or steel wire
armour, and perhaps as well an overall PVC or lead jacket for protection from moisture
and physical damage. Cables intended for very flexible service or in marine applications
may be protected by woven bronze wires. Power or communications cables (e.g.,
computer networking) that are routed in or through air-handling spaces (plenums) of
office buildings are required under the model building code to be either encased in metal
conduit, or rated for low flame and smoke production.
Mineral insulated cables at a panel board
For some industrial uses in steel mills and similar hot environments, no organic material
gives satisfactory service. Cables insulated with compressed mica flakes are sometimes
used. Another form of high-temperature cable is amineral insulated cable, with
individual conductors placed within a copper tube and the space filled with magnesium
oxide powder. The whole assembly is drawn down to smaller sizes, thereby compressing
the powder. Such cables have a certified fire resistance rating and are more costly than

36. 36
non-fire rated cable. They have little flexibility and behave more like rigid conduit rather
than flexible cables.
Because multiple conductors bundled in a cable cannot dissipate heat as easily as single
insulated conductors, those circuits are always rated at a lower "ampacity". Tables in
electrical safety codes give the maximum allowable current for a particular size of
conductor, for the voltage and temperature rating at the surface of the conductor for a
given physical environment, including the insulation type and thickness. The allowable
current will be different for wet or dry, for hot (attic) or cool (underground) locations. In
a run of cable through several areas, the most severe area will determine the appropriate
rating of the overall run.
Cables usually are secured by special fittings where they enter electrical apparatus; this
may be a simple screw clamp for jacketed cables in a dry location, or a polymer-
gasketed cable connector that mechanically engages the armour of an armoured cable
and provides a water-resistant connection. Special cable fittings may be applied to
prevent explosive gases from flowing in the interior of jacketed cables, where the cable
passes through areas where inflammable gases are present. To prevent loosening of the
connections of individual conductors of a cable, cables must be supported near their
entrance to devices and at regular intervals through their length. In tall buildings, special
designs are required to support the conductors of vertical runs of cable. Usually, only
one cable per fitting is allowed unless the fitting is otherwise rated.
Special cable constructions and termination techniques are required for cables installed
in ocean-going vessels; in addition to electrical safety and fire safety, such cables may
also be required to be pressure-resistant where they penetrate bulkheads of a ship.
Resistance to corrosion caused by salt water or salt spray is also required.