Electrical estimate and Costing For Project Calculation

ELECTRICAL ESTIMATE AND COSTING FOR PROJECT CLOSURE FULL GUIDELINES

Question and Answer:-
1) What is Electrical estimate and costing?
Ans:- The electrical estimation and costing means collecting details information of what are materials required for work and mentioning the cost of material is called estimation and costing.
2)What are the factors to be considered for electrical estimation and costing?
Ans: There are main major factors are

Factors to be considered for Selection of Wiring

Selection of wiring methods

Layout of wiring

Calculations of length of wire

1. Quality of wiring material for residential & commercial installation using suitable design of illumination system

Wiring diagram of individual switchboard

Preparation of bill of material (numerical)

 

Earthing

Method of earthing as per IS:732-1963

Estimation of cost of installation earthing

Requirement of earthing installation for substations

Residential and Commercial installation of earthing

Earth resistance for various installation

 

Overhead Lines

Main components

Types of Supports

Types of Insulators

Estimation and Costing of Overhead lines

Underground Cables

Types of Cables

Method of Laying of Cables

Estimation of cost of Underground cable installation

Differences between Overhead Transmission lines and Underground cables installations

 

Meaning of Terms using in Estimation & Costing

Principle of estimation purpose of estimation & costing

Approximate estimates

Detailed estimates

Preparation of detailed specification

Standard specification book

Market rate for Material & Labours

Standard schedules of rate

3) Briefly describe Electrical estimate and costing in Residential floor?

Ans) 

This is the plan where we should calculate everything i.e., what are the materials required for the plan and make a chat of materials with costing.

All dimensions are in a lotmeter

The following assumptions are made :

•  The height of the meter board, distribution board from the floor level = 2 meters.
•  Height of horizontal run and lighting fitting from floor level = 3 meters.
•  Height of switchboard from floor level = 1.5 
• circuits
  
  

  SI.NO	Location	Area(meter square)	Wattage (10W/m sq)	No	of	points	Types of fitting
  				lights	fans	socket
  01	Verandah	8	80	1×60	-	-	Pendent
  02	Room	12	120	1×40(FL)	1×80	1×60	Pendent
  				1×60(IL)			batten
  03	Hall	16	160	2×40	1×80	1×60	Pendent
  				1×60			& batten
  04	Kitchen	9	90	1×40	-	PS=2000	Pendent
  				1×60			& batten
  05	Passage	1.5	15	1×60	-	PS=1000	Pendent
  06	Bath roon	2.5	2.5	1×60	-		Pendent
  			Total load =	480w	160w	120w

  
  Total lighting circuit load = 480 + 160 + 120 = 760 watts

• Total heating circuit load = 3000 watts
  
  Total load of Installation = 760 + 3000 = 3760 watts
  
  No of the lighting circuit
                     = Total lighting circuit load/800
                     =  760/800 = 0.95
  
  If the total lighting circuit load exceeds 800 watts then two circuits must be provided, but here total lighting circuit load is less than 800 watts.
  
  Therefore, only one circuit is used.
  
  Hence from the Meter board, one lighting and one heating circuit are taken.
  

  Step-02

  
  Wiring diagram for the given plan:
  
  
  MB - Meter Board
  DB - Distribution Board
  SB - Switch Board contains switches & sockets
  
  

  Step-03 :

  
  
  Size of the wire
  
  
  To calculate any size of the wire, first we should calculate load current and by using a wire table size of the wire can be calculated.
  
  
  Load current = Total lighting circuit load/Voltage 
                        = 760/230 = 3.30 Amps
  let, a factor of safety be 2(for future demands or load)
  
  
  Current rating = load current * 2 
                          = 3.30 * 2 = 6.6 Amps
  
  
  
  
  Therefore, for lighting circuit 3/22 SWG copper wire
• Therefore, for lighting circuit 3/22 SWG copper wire is selected from the wire table
  
  

  Step-04:

  
  
  Length of Conduit required, use concealed conduit system of wiring.
  
  

  SI.NO	Location	Horizontal run	Vertical drop to switch	Vertical rise pipe line to ceiling fan	Wall crossing	Total
  01	Verandah	4+2	-	0.5		6.5
  02	Room	3+2	1	0.5		6.5
  03	Kitchen	3+1.5	1	0.5		6
  04	Hall	4+4+4	1	0.5	0.33 * 5 = 1.65 (overall)	12
  05	Passage	1+1.5+0.75	1	0.5		3.25
  06	Bath	1.25	1	0.5		2.75
  	Total				1.65	37
  
  
  Total = 37 + 1,65( wall crossing )
           = 38.65 = 39 (say)
  
  
  Total PVC conduit = 39 +5% wastage
                                = 40.95 = 41 meter  (say)
  
  

  Step-05:

  
  
  The total length of wire required
  
  
  length of wire(3/22 copper wire) = 41 * 3 
                                                       = 123 meter
  
  

  Step-06:

  
  
  Wood screws(assorted size) = 4(No of MB+SB)
                                               = 4(1 + 4)
                                               = 20 + 5% wastage
                                               = 21.95 Nos
  
  

  Step-07:

  
  
  The number of wood plugs required is  22 Nos as same as wood screws.
  
  

  Step-08:

  
  
  
  
  Other accessories required
  
  
  01. ICDP Switch 
  
  
  load current = 3.30 * 2 = 6.6 Amps
  A 15A ICDP switch is selected or 15A MCB is used.
  
  
  02. Switches = No of lamps + fans + sockets
                       = 12 + 2
                       = 14 Nos
  A 250 V, 5 A switches = 14Nos
  
  
  03. A 250 volts, 5 A, 3-Pin socket = 2 Nos
  04. No of fan regulators = 2 Nos 
  05. No of Pendant holder = 6 Nos
  06. No of Angle holder = 4 Nos
  07. No of ceiling roses = No of fan + No of pendant 
                                        = 2 + 6 = 8 Nos
  08. Fluorescent fitting, 230 V, 5 A = 4 set
  09. Ceiling fans, 230 V = 2 set
  10. Incandescent fitting = 6 set
  11. No of Tees = 4 Nos
  12. Meter Board = 1 Nos
  13. Switch Board = 4 Nos
  
  

  Step-09:

  
  
  Labor Charge
  
  
  The labor charge depends upon the number of points
  
  
  No of point 
             = (lights + fan + sockets) * 0.5 + MB + DB
             = (10 + 2 + 2) * 0.5 + 1 + 1
             = 15 Nos
  
  
  Labor Cost = Cost per point * No of points
                     = 195 * 15 = Rs 2970.00
  
  

  Step-10:

  Cost of Materials

  
  

  01. For heating load

  
  
  
  
  load current = Total heating circuit load / Voltage
                      = 3000 / 230 = 13.04 Amps
  
  
  Current rating = load current * Factor of safety
                         = 13.04 * 2 = 26.08 Amps
  
  
  Therefore, 7/20 SWG copper wire is selected.
  
  

  02. PVC Conduit required 

  
  
  Horizontal run = 4+2+4+1+2.5+1.5+3
                          = 18 meter
  Vertical drop = 1+1 = 2 meter
  Wall crossing = 0.33 * 4 = 1.32 meter
  Total PVC Conduit = 21.32 = 22 (25mm, 2mm thick)
  
  
  Therefore, Total PVC conduit = 22 + 10% wastage
                                                   = 24.2 = 25 meter
  
  

  03. Length of wire required

  
  
  Length of wire = 3 * length of PVC conduit
                           = 3 * 25
                           = 75 meter
  
  

  04. Wood screws (assorted size) = 4 * 2 

                                                      = 8 No + 5%
                                                      = 8.4 = 9 No's
  
  

  05. Wood Plugs = 9 No's

• (a) ICDP Switch

        Load current = 13.04, FOS = 3

        Current rating = 13.04 * 3 = 39.13 Amps

        A 250 V, 50 Amps selected

  
  

  (b) Switches - A 250 V, 15 A switches = 2 No's

  (c) 3-Pin socket = 2 No's

  (d) No of elbows = 2 No's

  (e) Switch board (200*250*45 mm) = 2 No's

  
  

  07. Labor Cost

  
  

  No of point = 2

  labor cost = 195 * 2 = 390
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