ESTIMATING AND COSTING IN ELECTRICAL ENGINEERING Electrical Engineering Fourth Semester

Detailed Contents Estimation Purpose of Estimating Qualities of good estimator Various Terms used Objectives Purchase System Requisition Form Tender Electrical Wiring System with types

Estimation Before any electrical project is initiated, it is essential to list out the materials required and compute the cost involved for completion of that work. Thus estimation consists of two parts; (a) preparing list of various items involved and (b) calculating the cost of materials and labour cost involved for executing the work. The quantity and specification of various materials required for installation work written in a tabular form is called schedule of materials. Determining whether to make an investment to provide a product for the consumer market

Purpose of Estimating Establish the bid price of a product for a quotation or contract. Verify quotations submitted by suppliers. Ascertain whether a proposed product can be manufactured and marketed profitably. Provide data for make-versus-buy decisions. Help determine the most economical method, process, or material for manufacturing a product. Provide a temporary standard for production efficiency and guide operating costs at the beginning of a project. Avoid misuse of money.

Qualities of good estimator Estimator have good knowledge Experience of work Good imagination Highly qualified. Disciplinary in nature

Performa for making estimates Serial No. Description of material Quantity Cost Amount 1 2 3 4

Various Terms used Quotation is a offer letter containing the rates of item. Labour charges are give to labour for installing/fitting of material Types of labour charge- Electrical point method,Fixed percentage method. Contingency charges are for uncertain and unexpected reasons these are also called emergency charge. Overhead charge includes tax paid to govt. rent of office.

Objectives Purchase System To make availability of required material with the desired specification. To purchase the material of good quality at lowest market price To make good relationship with all firms/companies. Proper procedure should be followed.

Requisition Form

Tender It is invitation of owner to the contractor to execute some work at specified cost in specified time. Classification of tender Single Tender : When only one source of supply is available then single tender is addressed to the selected supplier.  Limited Tender : This type of tender is addressed to a limited number of suppliers, who are the reliable source of supply. Open Tender : is open to all the suppliers within the country who can supply the required quantity and quality of materials. Such invitation is made by advertising in newspapers, journals etc.  Global Tender: is open to anybody from any part of the world to supply the required quantity and quality of materials.

Electrical Wiring System Wiring (a process of connecting various accessories for distribution of electrical energy from supplier’s meter board to home appliances such as lamps, fans and other domestic appliances is known as Electrical Wiring can be done using two methods which a Joint box system or Tee system Loop – in system

Different Types of Electrical Wiring Systems Cleat wiring Wooden casing and capping wiring CTS or TRS or PVC sheath wiring Lead sheathed or metal sheathed wiring Conduit wiring

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.

Casing and Capping wiring 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.

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

Conduit Wiring There are two additional types of conduit wiring according to pipe installation Surface Conduit Wiring Concealed Conduit Wiring

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