Meaning of estimation, purpose of estimating and the factors to be considered while preparing estimations, qualities of a good estimator, Meaning of specification, importance of specification and the factors to be considered. Meaning of standardization and its advantages. Meaning of overhead charges, stock incidental charges, contingencies, supervision charges, labour charges, Inspection/Inspectorate charges, transportation charges and miscellaneous charges. Meaning of tender/tender notice, quotation, comparative statement, purchase order and work order. Importance / purpose of IE Act and IE Rules. Meaning of earthing, touch potential and step potential, necessity of earthing, Points to be earthed, factors influencing earth resistance, methods of reducing earth resistance, standard values of earth resistance for various installations, method of selecting the size of earth conductor, types /methods of earthing, Pipe earthing-diagram, specifications of pipe earthing, Plate earthing-diagram and specifications of plate earthing.

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Prepared By:
Mr.Premanand Desai L/EE
B.L.D.E.A’s SHREE SANGANABASAVA
MAHA SWAMIJI POLYTECHNIC,
VIJAYAPUR-03
E-mail ID:ssmp.premananddesai@bldea.org
cell no : +91 7892881829
COURSE & CODE : ELECTRICAL ESTIMATION AND COSTING (15EE54T)
UNIT - 01
INTRODUCTION

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COURSE & CODE : ELECTRICAL ESTIMATION AND COSTING (15EE54T)
UNIT - 01
INTRODUCTION
1.1 Introduction
Before commissioning any work, it is important to know the clear picture of the
work, required materials, specification of the materials used and cost of the work.
1.2 Estimation
Estimation means an assessment of the quantity of the materials and its cost
required for any work. It includes listing of materials, stating their specifications
and Approximate cost.
OR
Estimation includes calculation of quantity involved and quality aspect of material ,
so estimation is the art of finding out the cost so that we can fix the budget for that
particular work.
1.3 Purpose/Need of Estimating
1. To Fix up the budget and complete details of the required materials for
carrying out the complete work.
2. To Exercise control over quality of materials required depending upon the
work to be executed.
3. To fix up the cost of various materials, including cost of labour ,
supervision , inspection ,transportation etc.
4. To find most economical procedure for the execution of work .
5. To keep the estimates in a systematic way for the future reference.
6. To ensure availability of all the materials required for execution of the
project.
7. To avoid the misuse of material and money.
8. To reduce the time required for completion of the project.
9. To complete the project uninterruptedly.

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1.4 Importance of Estimation
1. It give approximate budget for carrying out the work
2. Its avoids wastage of material.
3. It helps to use correct material.
4. It helps to do the work according to the engineering principles without any
confusion in adopting different systems or methods.
1.5 Factors to be considered while preparing estimations
Before initiating any electrical project the following factors related to estimation
should be considered
1. Standard Performa for making estimation.
2. Specification of the materials.
3. Latest price list and Net prices of materials.
4. Overhead charges, Supervision charges and Labour charges.
5. Contingencies and stock incidental charges.
6. Inspection charges and Transportation charges.
7. Miscellaneous charges.
1.6 Qualities of good estimator:
1. He should have full practical experience and knowledge about preparing
estimation.
2. He should have complete knowledge about the latest designs.
3. He should have full knowledge about the specification of materials and
market prices.
4. He should have knowledge about the labour charges and other charges.
5. He should have good imagination and experimenting power because he should
keep provision for future extension.

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1.7 Define specification.
Specification is a documented detailed description of materials, equipment’s and
machineries etc. suit to the requirements.
OR
Set of documented requirements to be satisfied by materials, equipment’s,
machineries, design etc. as per technical standard.
1.8 Importance of specification:
1. It provides clear details of the materials.
2. It gives quality and standards applied for materials.
3. It helps to purchase suitable materials.
4. It provides clear instructions about the quality of the materials.
5. It gives procedure for installation and using of materials.
1.9 Factors to be considered for specification:
1. Specification must be as per standards.
2. Economic factors to be considered.
3. Proper safety factor must be considered.
4. Specification must be as per the market availability of the materials.
1.10 standardization
It is a process to achieve interchangeability and quantity control so that mass
production is possible which reduces the cost. In India standards have been framed
by Bureau of Indian Standard.
1.11 Advantages or Need of standardization
1. Standardization minimizes the cost due to mass production.
2. It improves the quality of the material.
3. Standardization causes interchangeability due to which easy replacement of
material can be done.
4. Standardization avoids confusion to both supplier and user.

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1.12. Charges
1.12.1 Overhead charges:
Overhead charges include office expenses, salary of administrative staff, rents for
office, lighting and heating expenses, travelling expenses, advertisements, insurance,
and water expenses, depreciation of furniture’s etc. Normally 10-15% of the total
estimated material and labour expenses are spent on overhead charges.
1.12.2 Labour charges:
Labour charge is the most difficult and variable item to assess. It is affected by so many
factors such as installation site condition, skill and technical training, physical fitness
etc. By vast experience and proper records of time sheets, an intelligent estimator will
be able to obtain labour values by the system of man-hour constant.
1.12.3 Contingencies:
During erection of the project, there can be certain emergency expenses which cannot
considered while calculating the material cost and labour expenses for the project.
These additional emergency expenses may be due to any reason such as increase in cost
of material or labour rates etc. Such additional expenses are called contingencies. For
this, 3-5% of the material cost and labour cost is estimated.
1.12.4 Stock incidental charges:
To cover the risk of damage during preservation, transportation, loading, unloading and
handling or theft of material extra charge is included. It is normally 5% of total cost.
1.12.5 Inspection/Inspectorate charges:
Inspection or testing of any electrical work (Generating station, substation, transmission
line, distribution line etc) is done by government body for this charge is to be paid. So
inspection charges are included in the estimation as per standard inspectorial charges.
1.12.6 Transportation charges:
The cost of transporting materials or goods for the execution of a particular electrical
installation or project work is called transportation charges.

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1.12.7 Supervision charges:
These charges are paid for supervision of work to the licensee/contractor at 10% of the
estimated cost of the work.
1.12.8 Miscellaneous charges:
For purchasing of minor items like nuts, bolts, raw plugs, coal, salt etc which cannot be
mentioned in major works specification. The charges are paid in this head. The
miscellaneous charges included in the estimation are lump sum also rounded the cost of
estimation to a round figure.
1.12.9 Tender
A tender is a formal offer made by one to another to supply goods or to do a particular
job at certain specified cost. Generally business groups and Government departments’
issues notices for quotes for specified goods or services from other business or company
which known as tender. If a contract is put out to tender, formal offers are invited. If a
company wins a tender their offers is accepted.
1.12.10 Tender Notice
It is process to call venders for doing a certain job or provide certain service at a
competitive price. Usually done through the prominent newspaper of the region/official
e-procurement websites.
1.12.11 Quotation
An offer in terms of rates made by the supplier or manufacturer on a prescribed form
enclosed in a sealed envelope, in reply to a tender notice for supply of material on the
basis of some terms and a condition is called quotation.
1.12.12 Comparative statement
This is an important document to evaluate the offers received against an enquiry.
Utmost care must be exercised while preparing the comparative statement of tenders.
Any deviation from the tendered specifications, delivery conditions, assistance etc.
stipulated by the tenders should be highlight.
A sample of comparative price statement is as shown in Table below;

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Comparative Price Statement (CPS)
No. of Tenders Received: Enquiry No:
No. of Enquiries Issued: Date:
Date of Opening of
Tenders: Due Date:
Sl No Description Quantity Previous purchases Current Offers
Received Ordered Date Unit 1 2 3 4 5 6
No. Price
1.12.13 Purchase order
A purchase order is legally binding document between a supplier and a buyer. It details
the items the buyer agrees to purchase at a certain price point. It also outlines the
delivery date and terms of payment for the buyer purchase order computer systems
have made the purchasing process more efficient and allow for better inventory and
payment tracking.
1.12.14 Work order
A work order is an order received by an organization from a customer or client or an
order created internally within the organization. A work order may before products or
services. A work order sometimes is used in place of an "invoice" or "statement" and
presented for payment requests.
1.13 Indian Electricity Act (I.E Act)
An Act to amend the law retaining to the supply and use of electrical energy, rights and
obligations of the licensees. Whereas it is expedient to amend the law relating to the
supply and use of electrical energy. This Act may be called the Indian Electricity Act;
1910.It extends to the whole of India.
The Electricity Supply Act, 1948 deals with the statutory powers and functions of the
Central Electricity Authority. State electricity boards and generating companies. The
electricity act 2003 is enacted to improve the backdrop of economic in power sector and

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performance of state electricity boards. This deals with uniform and unified law to take
care of the current needs of power sector in the areas of generation, transmission,
trading and distribution of electricity.
1.14 Importance of Indian Electricity Act
1. It is a single legislation which addresses all the key areas of electricity in the
country.
2. It provides a road map for overall and uniform development of electricity
sector in the country
3. It takes care of interests of consumers belonging to various sectors
4. It also aims to reform the sector to suit the needs of the present day
requirement in the light of globalization.
5. Through specific provisions it aims to bring in financial and commercial
viability for power sector utilities.
1.15 Purpose of Indian Electricity Act
1. To consolidate the laws relating to generation, transmission, distribution,
trading and use of electricity.
2. To take measures conducive for development of electricity sector.
3. To promote competition in the power sector.
4. To protect the interests of consumers.
5. To rationalize the electricity tariffs.
6. To establish regulatory commissions and appellate tribunal for electricity.
1.16 Indian electricity rules (IE Rules)
In exercise of the powers conferred by section 37 of the Indian electricity act,1910
the central electricity board frames the rules to regulate the generation,
transmission, supply and use of electrical energy. These rules called as Indian
electricity rules 1956.
1.17 Importance of Indian Electricity Rules
• They provides reliability and safety for electrical supply system
• They focus on protection of persons and property from injury.

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• They supplement the various codes of bureau of Indian standards.
• They serve as a guideline for electrical practices in a country.
1.18 Purpose of Indian electricity rules
• To regulate the relation between the supplier and consumer.
• To make the generation, transmission and distribution of electricity as safe
as possible.
1.19 Earthing
The process of connecting metallic bodies of all the electrical apparatus and
equipment to huge mass of earth by a wire having negligible resistance is called
Earthing.
OR
The method of connecting noncurrent carrying parts of the electrical equipment or
accessories or neutral point of the supply, system to the earth through the wire
having negligible resistance is called electrical earthing.
1.19.1 Touch potential:
Touch potential is the potential difference between the energized object and the
feet of a person in contact with the object.
1.19.2 Step potential:
Step potential is the potential difference between the feet of a person standing
near an energized grounded object.

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1.20 Necessity of earthing
• To provide a protection for the apparatus, equipment’s, devices etc.
against leakage current this may damage it.
• To provide safety to the operator or the person coming in touch with
electric supply.
• Tripping due to earthing in case faults save wastage of electric energy
excess current drawn during.
• Protection of large buildings and all machines fed from overhead lines
against lightning.
• To serve as a returned conductor in communication and traction work.
• To maintain the line voltage constant under unbalanced load condition
1.21 Points to be earthed:
1 Earth pin of sockets should be efficiently and permanently earthed.
2 All metallic covers of machines, starters and sheathing of wire should be
earthed.
3 Iron clad switches and iron clad distribution boards should be earthed.
4 Metallic coverings of any electrical supply line should be earthed.
5 Stay wires for overhead lines should be connected to earth.
6 In a dc 3-wire system, the middle conductors should be earthed at the
generating station.
1.22 Factors influencing earth resistance:
• Soil resistivity: The earth resistance of an earth pit depends on soil resistivity.
• Soil condition: Different soil gives different earth resistance.
• Moisture: Moisture content is one of the controlling factors in earth
resistivity.
• Dissolved salts: Small quantity of salt reduces the earth resistivity.

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• Temperature: As the temperature changes the earth resistance also changes.
• The type of material used for earth electrode and earth wire.
• Size of earth electrode and earth wire.
1.23 Methods of reducing earth resistance
• Pour sufficient water in earth electrode periodically.
• By increasing the cross sectional area of electrode.
• By maintaining the temperature of the soil.
• By increasing depth of the plate.
• By installing number of electrodes in parallel.
• Using sufficient quantity of coal and salt in the earthing pit.
• Remove oxidation on joint and joints should be tightened.
1.24 Standard values of earth resistance for various installations.
• Large power station – 0.5 Ω
• Major Power Station – 1.0 Ω
• Small Substation – 2.0 Ω
• In all other cases – 5 Ω Maximum
Earth continuity inside an installation that is from the earth plate to any
point in the installation -1.0 Ω

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1.25 Method of selecting the size of earth conductor.
• For domestic Installation : GI or Copper Wire no. 8 SWG will be required to run from
main distribution board to various submain distribution boards. Copper wire no.14
SWG will be required to run to three-pin socket outlets and connected to their earth
sleeve.
• For Motor Installation : In case of motor installation, the size of earth wire and earth
plate used will depend upon the rating of the motor for which it is to be used.
1.26 Types / Methods of Earthing
• Strip or Wire or Spiral Earthing
• Rod Earthing
• Mat Earthing
• Plate Earthing
• Pipe Earthing
1.27 Plate Earthing
The plate earthing is as shown in the Figure 2. In this method a copper plate of 60cm
x 60cm x 3mm or a GI plate of the size 60cm x 60cm x 6mm is used for earthing. The
plate is placed vertically down inside the ground at a depth of 3m and is embedded
in alternate layers of coal and salt for a thickness of 15 cm.
In addition, water is poured for keeping the earth electrode resistance value well
below a maximum of 5 ohms. The earth wire is securely bolted to the earth plate. A
cement masonry chamber is built with a cast iron cover for easy regular maintenance.
Capacity of motor /
Equipment
Size of earth wire in S W G
Copper G.I
Up to 10 hp No 8 No 8
Above 10 hp & up to 15 hp No 8 No 6
Above 15 hp & Up to 30 hp No 6 No 2
Above 30 hp & Up to 50 hp No 4 -
Above 50 hp & Up to 100 hp No 2 or Strip 13mm × 2.5mm -
Above 100 hp Strip 25 mm × 2.5mm -

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1.27.1 Specification Plate Earthing
Sl No Description Specification
1 Earth pit 1mtr diameter 3mtr depth
2 Pipe for earth conductor GI 50mm dia, 2mtr length
3 Earth electrode plate size Copper plate of 600mm x 600mm x 3mm or
GI plate of 600mm x 600mm x 6mm
4 Earth strip for connection Copper earth strip of 25mm x 3mm
5 Filling of earth pit With charcoal and salt surrounding earth
plate about 150mm
6 Pipe for water pouring 19 mm dia GI pipe
7 Construction of masonry Masonry brick work of height 450mm x
work width 700mm with CI cover and CI frame

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1.29 Pipe Earthing
Pipe earthing is done by G.I. pipe as shown in Figure.1. Here a 38mmdia G.I.pipe
2.5m in length, 3 mm thickness having alternate cross holes of 12.mmdia at each
300 mm distance buried in a pit of 340mm diameter with alternative layers of coal
and salt.
The top of this pipe is connected to the funnel through 19 mm GI, pipe with the
help of a reducer. At ground level a concrete bed is formed in such a way that a
hollow rectangular solid shape is formed (150mm X 150mm X 250mm) with the
insertion of GI pipe carrying the earth conductor.
The above hollow pit is closed by Cast Iron cover. Pipe is connected to the apparatus
by means of 8 SWG G I. wire with the help of bolts and nuts. To maintain the wetness
in pit periodically (After every eight days in summer and winter) water is poured
through the funnel. Always the earth resistance should be within 2 to 5 ohms, but
for rocky soil it can be more.

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1.29.1 Specification Plate Earthing
Sl No Description Specification
1 Earth pit 1mtr diameter 4.5mtr depth
2 Pipe for earth conductor GI 40mm dia, 2.5mtr length, 3mm thickness
3 Pipe for water pouring 19 mm dia GI pipe
4 Filling of earth pit Alternative layer of charcoal and salt 2mtr
from the bottom of pipe.
5 Construction of masonry Masonry brick work of height 450mm x
work width 700mm with CI cover and CI frame
6 Identification of earth pit With suitable display board

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MODEL QUESTIONS BANK
• Cognitive Level: REMEMBER
1. Define estimation. List the factors to be considered while estimating.
2. List the qualities of a good estimator.
3. List the importance of estimation.
4. Define specification. List the factors to be considered.
5. Mention the importance of specification.
6. Define standardization. List the advantages.
7. Define earthing?. List the points that need to be earthed.
8. Draw a neat diagram of pipe earthing and label the parts.
9. Draw a neat diagram of plate earthing and label the parts.
10.List the specification of pipe earthing
11.List the specifications of plate earthing.
12.List the factors on which earth resistance depends.
13.List the methods of reducing earth resistance.
• Cognitive level: Understanding/Analyse
1. Draw neat diagram of pipe earthing and label the parts with specifications.
2. Draw neat diagram of plate earthing and label the parts with specifications.
3. List the specifications of a) pipe earthing and b) plate earthing