Approval Of Drawings

Application for approval of drawings in respect of newly established Power House, Master Unit sub-stations, switching stations, Master Receiving stations, Transmission Lines, Inter linking lines and Under Ground cable laying of supplier installation, IPPs and Mining Installations shall be submitted to the Chief Electrical Inspector, HP and consumer installations of LT, HT, MSB of 15m and above & DG set installation shall be submitted to the Electrical Inspectorate with all the relevant drawings and details as listed below for the particular category of installation:-


  1. Requisition Letter
  2. Copy of work award letter.
  3. Two sets of blue print drawings or computer print drawings incorporating items listed under SL. No 5 below.
  4. All the drawings shall be duly signed by the concerned officer not below the rank of Sr. Executive Engineer in case of supplier installations or the consumer/owner or authorized signatory in respect of the consumer installation as well as the Licensed Electrical contractor enlisted with this Inspectorate who is executing the works.
  5. Drawings shall be:
  • Single Line Diagram of electrical installation showing all details from starting point to end point of the entire installation (For additions or alterations existing and proposed scheme shall be legibly marked)
  • Site plan showing the location of transformer, Generator, Electrical Room, Panels, motors, etc.
  • Physical Layout/Plan: The Physical layout of the installation should show the location of all the equipments in relations to the location of switchboards and distribution boards. The clearance around the switchboards, distribution boards and main panels shall be indicated legibly.
  • Elevation in sections showing overhead clearance, Horizontal, Vertical and sectional clearances with respect to equipments and ground.
  • Method of construction of Earth pits / Earth mat as per standards and method of cable laying.


DRAWINGS TO BE FURNISHED: Sub-stations/Switch stations.

  • Single line schematic showing all the Electromechanical Equipments, instrumentation of CT’s, PT’s, Relays, Circuit Breakers, Metering, size/ description of cables/overhead line, connected Surge arrestors, Capacitors Banks, Auxiliary Transformers & auxiliary station loads & its metering.
  • Key plan showing location of the sub-station, incoming/outgoing lines, control room, etc.
  • Plan of the switchyard showing all-round clearances with respect to equipments, structures etc.
  • Sectional Elevation of the sub-station showing mounting structures/equipments and their clearance to ground, sectional clearances
  • Plan and sectional elevation of control room showing arrangement of control panels with adequate all round clearance as per provision of I E Rules, 1956.
  • Method of cable laying inside the substation and control room.
  • Plan showing oil drain route arrangement and elevation of baffle wall between transformers wherever applicable.
  • Earthing Layout as per ISS 3043/1987.


For Transmission line/power evacuation line Drawing approval

  • Route profile showing details including all power line crossings, railway crossings, rivers, canals, National highways, buildings/ structures, telecommunication lines, oil and gas pipe lines, etc. on either side of the route of the line shall be drawn to the scale with longitude and latitude properly marked.
  • Tower schedule
  • Tower Earthing details
  • PTCC approval
  • NH clearance
  • Railway clearance
  • Any other statutory approvals as required depending on site conditions

CONSUMER INSTALLATIONS: (EHV/HV, DG, MSB, additions or alterations to the existing installation)

Power availability/sanction letter from supplier/Licensee in respect of HV consumers installations, Copy of the building plan and elevation approved from competent authority showing area statement of each floor level in respect of Multi Storeyed Building.


  • Single line schematic showing capacity of Transformer, Generator, Number of runs and size of HT/LT cable, capacity of HT/LT breakers and protective relays, connected loads on each Panel, Load details of common area lighting, external lighting, UPS, AC/AHU loads, Fire hydrant system loads panel directly tapped from main supply panel, Lifts panel showing separate circuits for lift power and lighting circuits for each lift installation, connected panel loads of individual floors indicating load on each phase, no. of rising mains circuits with capacity and size of raising mains and end feeders along with emergency power supply source.
  • Key plan showing approach road to the site/ building, incoming supply tapping details, location of the building, Transformer centre / HT sub-station, DG room, all major motors and electrical panel, all the earth pits etc .
  • Plan and sectional elevation of transformer yard and / or D G set room, and electrical room with all-round clearances.
  • Method of cable laying.
  • Earthing layout of entire installation showing construction of earth pits as per standards. cross section of earth pit, earthing conductor size, no. of earth pits etc.
  • For Multi-storeyed building: In addition to the above, sectional elevation of the building showing number of floors, electrical shaft/duct, bus bar trunking, fire alarm, earthing, lightning arrestor and its Earthing, aviation lamp etc. and floor wise plan showing location of distribution boards, fan and light points, Fire alarm, Manual call points, Public address system etc.


Documents required to be submitted along with the drawing are;

  • Govt. order for having obtained permission for setting up of power plant.
  • Power purchase agreement copy.
  • Scheme of grid synchronization.
  • Power Evacuation infrastructure details including sending and receiving end equipments.


  • Topographical map showing location of the power plant/unit.
  • Single line schematic of entire project
  • Sectional plan and elevations
  • Earthing scheme

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