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ELECTRICAL ESTIMATION ANDCOSTING
LECTURE NOTES
B.TECH
(III YEAR – I SEM)
Prepared by:
M.KUMARA SWAMY., Asst.Professor
Department of Electrical& Electronics Engineering
MALLA REDDY COLLEGE OF
ENGINEERING&TECHNOLOGY
(Autonomous Institution – UGC, Govt. of India)
Recognized under 2(f) and 12 (B) of UGC ACT 1956
(Affiliated toJNTUH, Hyderabad, Approved by AICTE - Accredited by NBA& NAAC – ‘A’ Grade - ISO 9001:2015 Certified) Maisammaguda,Dhulapally (PostVia. Kompally), Secunderabad – 500100,Telangana State, India
MALLA REDDY COLLEGE OF ENGINEERING AND TECHNOLOGY
III YEAR B.Tech EEE– ISEM L/T/P/C
(PROFESSIONAL ELECTIVE – I)
(R20A0215) ELECTRICAL ESTIMATION ANDCOSTING
COURSE OBJECTIVES:
- Emphasize the estimating and costing aspects of all electrical equipment, installation and designs to analyze the cost Aviability.
- Exposure to design and estimation of wiring, design of overhead and underground distribution lines, substations and illuminations design.
- These techniques should help the students to successfully estimate costing of the products/projects that are part of our everyday usage.
- a basic knowledge on methods and types of estimation and its merits and demerits
- To prepare the schedule of materials with specifications and estimates for different types of electrical installations.
UNIT‐I:
DESIGN CONSIDERATIONS OF ELECTRICAL INSTALLATIONS: Electric Supply System, Three
phase four wire distribution system, Protection of Electric Installation against over load, short circuit and Earth fault, Earthing, General requirements of Electrical Installations, testing of installations, Indian Electricity rules, Neutral and Earth wire, Types of loads, Systems of wiring, Service connections, Service Mains, Sub‐Circuits, Location of Outlets, Location of Control Switches, Location of Main Board and Distribution Board, guide lines for Installation of Fittings, Load Assessment, Permissible voltage drops and sizes of wires, estimating and costing of Electricl installations.
UNIT‐II:
ELECTRICAL INSTALLATION OF BUILDINGS AND SMALL INDUSTRIES: Electrical installations
for residential buildings – estimating and costing of material, Electrical installations for commercial buildings, Electrical installations for small industries.
UNIT‐III:
OVERHEAD AND UNDERGROUND TRANSMISSION AND DISTRIBUTION LINES: Introduction,
Supports for Transmission lines, Distribution lines – Materials used, Underground cables, Mechanical Design of overhead lines, Design of underground cables.
COURSE OUTCOMES:
After going through this course the student gets knowledge on:
- The estimating and costing aspects of all electrical equipment, installation and designs to analyze the cost viability.
- Exposure to design and estimation of wiring, design of overhead and underground distribution lines, substations and illuminations design.
- To design illumination systems.
- Understand types of substations and their ratings.
- These techniques should help the students to successfully estimate costing of the products/projects that are part of our everyday usage and apply the above concepts to real‐ world electrical and electronics problems and applications.
ESTIMATING AND COSTING IN ELECTRICAL ENGINEERING
LEARNING OUTCOME
After undergoing the subject, student will be able to:
Determine various types of wiring systems and how they are being used Practice and execute any type of wiring Estimate and determine the cost of wiring installation Estimate the material required for HT and LT lines Prepare a tender document for a particular job Estimate the material required for pole-mounted sub-stations
Chapter:
1. Introduction Purpose of estimating and costing, proforma for making estimates, preparation of materials schedule, costing, price list, preparation of tender document (with 2-3 exercises), net price list, market survey, overhead charges, labour charges, electrical point method and fixed percentage method, contingency, profit, purchase system, enquiries, comparative statements, orders for supply, payment of bills.
1.1 Types of Wiring
1.2 Cleat Wiring
This system of wiring comprise of ordinary VIR or PVC insulated wires (occasionally, sheathed and weather proof cable) braided and compounded held on walls or ceilings by means of porcelain cleats, Plastic or wood.
Cleat wiring system is a temporary wiring system therefore it is not suitable for domestic premises. The use of cleat wiring system is over nowadays.
4.Conduit Wiring There are two additional types of conduit wiring according to pipe installation.
. Surface Conduit Wiring . Concealed Conduit Wiring
Surface Conduit Wiring
If conduits installed on roof or wall, It is known as surface conduit wiring. in this wiring method, they make holes on the surface of wall on equal distances and conduit is installed then with the help of rawal plugs.
Concealed Conduit wiring
If the conduits is hidden inside the wall slots with the help of plastering, it is called concealed conduit wiring. In other words, the electrical wiring system inside wall, roof or floor with the help of plastic or metallic piping is called concealed conduit wiring. obliviously, It is the most popular, beautiful, stronger and common electrical wiring system nowadays.
In conduit wiring, steel tubes known as conduits are installed on the surface of walls by means of pipe hooks (surface conduit wiring) or buried in walls under plaster and VIR or PVC cables are afterwards drawn by means of a GI wire of size if about 18SWG.
In Conduit wiring system, The conduits should be electrically continuous and connected to earth at some suitable points in case of steel conduit. Conduit wiring is a professional way of wiring a building. Mostly PVC conduits are used in domestic wiring.
The conduit protects the cables from being damaged by rodents (when rodents bites the cables it will cause short circuit) that is why circuit breakers are in place though but hey! Prevention is better than cure. Lead conduits are used in factories or when the building is prone to fire accident. Trunking is more of like surface conduit wiring. It’s gaining popularity too.
It is done by screwing a PVC trunking pipe to a wall then passing the cables through the pipe. The cables in conduit should not be too tight. Space factor have to be put into consideration.
Types of Conduit
Following conduits are used in the conduit wiring systems (both concealed and surface conduit wiring) which are shown in the above image.
. Metallic Conduit . Non-metallic conduit
Metallic Conduit:
Metallic conduits are made of steel which are very strong but costly as well.
There are two types of metallic conduits.
residential, commercial or industrial wiring. These factors include type of building construction, type of ceiling, wall and floor construction, wiring methods, installation requirements, etc.
Circuit Drawing (Diagram)
In this, electrical circuit is graphically represented in a simplified manner. It includes the position information (in cm or m or mm) of various elements like light fixtures, receptacle boxes, junction boxes, ceiling fans, etc
6. Domestic And Industrial Wiring. . Domestic wiring: . The electric power line enters our house through three wires- namely the live wire, the neutral wire and the earth wire. To avoid confusion we follow a color code for insulating these wires. The red wire is the live wire, and the black wire is neutral. The earth wire is given green plastic insulation.
The live wire has a high potential of 220 volts whereas the neutral wire has zero potential. Thus the potential difference between the live wire and the neutral wire is 220-0 220 volts.
The earth wire is much thicker in size and is made of copper. One end of it is connected to a copper plate buried deep under the earth. The earth connection is made to the electric meter and then to the main switch.
. Industrial Wiring To increase the productivity and to avoid the accident hazardous, factory lighting should fulfill the following requirements.
i It should produce sufficient illumination on the working plane.
ii It should provide uniform distribution of illumination.
iii It should avoid glare and shadows.
iv It should be easy to clean.
7. Use of wire-gauge
Wire gauge is a measurement of wire diameter. This determines the amount of electric current a wire can safely carry, as well as its electrical resistance and weight.
Chapter:
Estimating and Costing
2.1 Domestic installations:
Using the very latest in technology and we can build you a complete wiring installation to suit your home. We design breathtaking lighting systems which can be coupled to home automation for a totally modern yet warm ambience. The wide range of lighting now available with LED technology is now very cost effective with lower purchase costs and lower energy usage which is good for the environment.
We have worked with reknowned widely acclaimed architects to deliver a complete turnkey package from its conception to fruition for many satisfied clients. You can rest assured that all our engineers are trained to the very highest standards and possess the qualifications to carry out the job at hand. We certify each and every installation we work on and register it with the local authority having jurisdiction.
Estimating Materials Required 2.1. Transmission and distribution lines
.Transmission: Various generating stations generate electrical power. These generating stations are not necessarily situated at the load center. During construction of generating station number of factors are to be considered from the economic point of view. These all factors may not be easily available at load center; hence generating stations are not normally situated very nearer to load center. Load center is the place which consumes maximum power.
. Distribution lines: The main function of an electrical power distribution system is to provide power to individual consumer premises. Distribution of electric power to different consumers is done with much low voltage level.
.Underground and Overhead
Underground : Underground cables are more expensive to construct since they have to be electrically insulated and have protection against moisture, corrosion, mechanical damage and other environmental impacts from the soil. Construction of the cables is more complicated compared to the overhead cables which are simple to construct, and do not require insulation and sheathing. The overhead cables have lesser requirements and cheaper to construct.
. Overhead
Nobody should climb any tower carrying live overhead conductors.
twinges to the live over head lines.
proper shutdown and temporary earthing arrangement. In this case nobody should be allowed to come closer to the snapped or hanged conductor until the entire circuit is isolated and earthed from both ends substations. In additions to that the snapped conductors should also be locally temporarily earthed with proper earthing rod before touching it for repairing work.
he live conducting parts of over head system, we should immediately inform to the concerned authority.
. Earthing
The main reason for doing earthing in electrical network is for the safety. When all metallic parts in electrical equipments are grounded then if the insulation inside the equipments fails there are no dangerous voltages present in the equipment case. If the live wire touches the grounded case then the circuit is effectively shorted and fuse will immediately blow. When the fuse is blown then the dangerous voltages are away.
- Plate type Earthing
.Railway Substation:
Electrified railways also use substations, often distribution substations. In some cases, a conversion of the current type takes place, commonly with rectifiers for direct current (DC) trains, or rotary converters for trains using alternating current (AC) at frequencies other than that of the public grid. Sometimes they are also transmission substations or collector substations if the railway network also operates its own grid and generators to supply the other stations.
. Substation Schemes and Component
The power grid is an essential element in the generation of electricity, transmission as well as distribution systems. Electrical substations are mandatory for all the processes of the power grid. These are essential devices used to generate electrical power from the substations. By changing the levels of frequency, voltage, the required amount of electricity can be changed in substations for supplying electricity to customers. An electrical substation is categorized into various types, such as generation, pole mounted, indoor, outdoor, converter, distribution, transmission, switching substations. In some cases like thermal plant, several hydroelectric, and wind farm electricity generation system, one can notice the collector substation, which can be useful for power transfer from several turbines in the only transmission unit.
. Estimate of 11/0.4 kV pole mounted substation up to 200 kVA rating
of the material, investment involved, and the time to be taken for the completion of Electrification project Normally it can be enlisted under following four headings. - Estimating the quantity of the material and the cost involved. - Analysis of cost or selling price. - Maintaining proper accounts. - Provision of selling aids. TIAL ELEMENTS OF ESTIMATING Specification of material. Latest market cost of material. Calculation of material and labour cost. Knowledge of purchase system.
distribution. Their main functions are to receive energy transmitted at high voltage from the generating stations, reduce the voltage to a value appropriate for distribution and provide facilities for switching.
. Key Diagram of 66 kV/11 kV Substation
2.3. Single line diagram, layout sketching of outdoor
. Indoor 11kV sub-station or 33kV sub-station REC has issued Construction Standards L-1 and L-2 indicating the standard layout for 33/11kV sub-stations with outdoor and indoor 11kV switchgear respectively. Thestandard layout should be followed for all 33/11kV sub-stations in the rural distributionsystems as far as practicable.3.3.2 The standard layout recommended by the REC is suitable for two power transformersand five outgoing 11kV feeders including two feeders for future. In case of indoor 11kVswitchgear, provision has been made for four existing and two future 11kV panels andone bus-coupler panel has also been provided. The 33kV incoming arrangement willdepend upon the requirement of each case, i.e. whether there are one or two incoming33kV lines and whether any 33kV line and whether any 33kV line/lines are proposed tobe taken out from the sub-station. The arrangement for the 33kV incoming and outgoinglines may be followed as per standard practice of the Board. However, an arrangementshowing one incoming line and two outgoing lines has been suggested in the standardlayout (shown dotted).3.3.3 The standard layout (with out-door 11kV switchgear) shows only the generalarrangement of the equipments, structures, bus bars etc., but the provision for internalroads/paths has not been shown. It is important that suitable provision is made in theswitchyard depending upon the local conditions for roads/paths to facilitatetransportation/shifting of the heavy equipment particularly the power transformers. Itwould be desirable if a truck can be taken to the site of the transformer for easy shiftingof the transformer. In case of 5MVA transformers, it may be necessary to use a trailer for the purpose of transportation. It would be desirable to make provision accordingly.
Chapter:
Preparation of Tender Documents
