Electrical Estimation and Costing Chapter Notes | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE) PDF Download

 Page 1


 
 
   
   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 
 
 
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. 
 
Page 2


 
 
   
   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 
 
 
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. 
 
 
    1.3   Casing and Capping wiring 
 
     Casing and Capping wiring system was famous wiring      system in the past but, it is 
considered obsolete this days because of Conduit and sheathed wiring system. The cables 
used in this kind of wiring were either VIR or PVC or any other approved insulated cables. 
     The cables were carried through the wooden casing enclosures. The casing is made up of a 
strip of wood with parallel grooves cut length wise so as to accommodate VIR cables. The 
grooves were made to separate opposite polarity. the capping (also made of wood) used to 
cover the wires and cables installed and fitted in the casing 
 
 
3.Batten Wiring (CTS or TRS) 
 
     Single core or double core or three core TRS cables with a circular oval shape cables are used 
in this kind of wiring. Mostly, single core cables are preferred. TRS cables are chemical 
proof, water proof, steam proof, but are slightly affected by lubricating oil. The TRS cables 
are run on well seasoned and straight teak wood batten with at least a thickness of 10mm. 
     The cables are held on the wooden batten by means of tinned brass link clips (buckle clip) 
already fixed on the batten with brass pins and spaced at an interval of 10cm for horizontal 
runs and 15cm for vertical runs. 
Page 3


 
 
   
   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 
 
 
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. 
 
 
    1.3   Casing and Capping wiring 
 
     Casing and Capping wiring system was famous wiring      system in the past but, it is 
considered obsolete this days because of Conduit and sheathed wiring system. The cables 
used in this kind of wiring were either VIR or PVC or any other approved insulated cables. 
     The cables were carried through the wooden casing enclosures. The casing is made up of a 
strip of wood with parallel grooves cut length wise so as to accommodate VIR cables. The 
grooves were made to separate opposite polarity. the capping (also made of wood) used to 
cover the wires and cables installed and fitted in the casing 
 
 
3.Batten Wiring (CTS or TRS) 
 
     Single core or double core or three core TRS cables with a circular oval shape cables are used 
in this kind of wiring. Mostly, single core cables are preferred. TRS cables are chemical 
proof, water proof, steam proof, but are slightly affected by lubricating oil. The TRS cables 
are run on well seasoned and straight teak wood batten with at least a thickness of 10mm. 
     The cables are held on the wooden batten by means of tinned brass link clips (buckle clip) 
already fixed on the batten with brass pins and spaced at an interval of 10cm for horizontal 
runs and 15cm for vertical runs. 
 
 
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. 
Page 4


 
 
   
   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 
 
 
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. 
 
 
    1.3   Casing and Capping wiring 
 
     Casing and Capping wiring system was famous wiring      system in the past but, it is 
considered obsolete this days because of Conduit and sheathed wiring system. The cables 
used in this kind of wiring were either VIR or PVC or any other approved insulated cables. 
     The cables were carried through the wooden casing enclosures. The casing is made up of a 
strip of wood with parallel grooves cut length wise so as to accommodate VIR cables. The 
grooves were made to separate opposite polarity. the capping (also made of wood) used to 
cover the wires and cables installed and fitted in the casing 
 
 
3.Batten Wiring (CTS or TRS) 
 
     Single core or double core or three core TRS cables with a circular oval shape cables are used 
in this kind of wiring. Mostly, single core cables are preferred. TRS cables are chemical 
proof, water proof, steam proof, but are slightly affected by lubricating oil. The TRS cables 
are run on well seasoned and straight teak wood batten with at least a thickness of 10mm. 
     The cables are held on the wooden batten by means of tinned brass link clips (buckle clip) 
already fixed on the batten with brass pins and spaced at an interval of 10cm for horizontal 
runs and 15cm for vertical runs. 
 
 
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. 
 
Page 5


 
 
   
   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 
 
 
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. 
 
 
    1.3   Casing and Capping wiring 
 
     Casing and Capping wiring system was famous wiring      system in the past but, it is 
considered obsolete this days because of Conduit and sheathed wiring system. The cables 
used in this kind of wiring were either VIR or PVC or any other approved insulated cables. 
     The cables were carried through the wooden casing enclosures. The casing is made up of a 
strip of wood with parallel grooves cut length wise so as to accommodate VIR cables. The 
grooves were made to separate opposite polarity. the capping (also made of wood) used to 
cover the wires and cables installed and fitted in the casing 
 
 
3.Batten Wiring (CTS or TRS) 
 
     Single core or double core or three core TRS cables with a circular oval shape cables are used 
in this kind of wiring. Mostly, single core cables are preferred. TRS cables are chemical 
proof, water proof, steam proof, but are slightly affected by lubricating oil. The TRS cables 
are run on well seasoned and straight teak wood batten with at least a thickness of 10mm. 
     The cables are held on the wooden batten by means of tinned brass link clips (buckle clip) 
already fixed on the batten with brass pins and spaced at an interval of 10cm for horizontal 
runs and 15cm for vertical runs. 
 
 
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. 
 
     Class A Conduit: Low gauge conduit (Thin layer steel sheet conduit) 
     Class B Conduit: High gauge conduit (Thick sheet of steel conduit) 
 
     Non-metallic Conduit: 
 
     A solid PVC conduit is used as non-metallic conduit now a days, which is flexible and easy 
to bend. 
 
     Size of Conduit: 
 
     The common conduit pipes are available in different sizes genially, 13, 16.2, 18.75, 20, 25, 
37, 50, and 63 mm (diameter) or 1/2, 5/8, 3/4, 1, 1.25, 1.5, and 2 inch in diameter. 
 
    Comparison between Different Wiring Systems 
 
     Below is the table which shows the comparison between all the above mentioned wiring 
systems. 
 
 
 
 
5. Electrical Wiring Systems and Methods of Electrical Wiring 
 
     The electrical wiring must be installed correctly and safely in accordance with electrical 
regulations and standards. If the electrical wiring is carried incorrectly or without 
confirming to any standard, devices could damage or leads to the malfunctioning of device 
which further causes for the reduction of device life.  
 
      
 
 
       Several factors have to be considered before the actual installation work to be done for