Procedures For Drawing Approval

1. The procedures to be followed by the consumer in complying with regulations and required technical standards for commissioning the installation are covered in this chapter.

2. The following stages of compliances are involved in the commissioning of an electrical installation

• Obtaining Load Sanction from the TANGEDCO.
• Obtaining No objection certificate from the TANGEDCO, if the proposal involves paralleling of Generator set(s) with TANGEDCO’S grid.
• Obtaining Electrical Inspectorate’s approval for the drawing proposal
• Erection and Completion of the Electrical Works based on the drawings approved by the Electrical Inspectorate.
• Supplier's load sanction letter.
• Submission of Completion Report for works completed.
• Rectification of defects pointed out after inspection and submission of Rectification Report
• Commissioning and Reporting.
• Additions and Alterations to the existing installations.

3. Stages Of Compliance Involved At Electrical Inspectorate.

3.1. approval of drawing.

The following drawings are required to be sent to the electrical Inspectorate for approval:

• Site plan.
• Point of Supply and Sub-Station Layout.
• Schematic Layout.
• Physical Layout.
• Generator Layout.
• OH Lines Layout.

3.1.1. Site plan.

A site plan showing clearly the following:

• Topo plan showing the geographic location of installation with reference to the roads, village/town and land mark.
• Boundary of the property with SF numbers, public road, canals or entities other than the consumer, if any ,within the boundary.
• Location of the supplier’s point of supply,viz; Location of supplier’s structure/ RMG room along with the route of supplier’s HT incoming OH lines /HT incoming cable.
• Location of consumer’s structure/HT gears near the point of supply, Transformer, Generator and main panel room.
• The route of the HT OH lines, if any, passing inside and adjoining the premises.
• Location of various buildings, Halls, Sections etc.
• Internal roads, clearance between the Transformer and its secondary control gear.
• In the case of multistoried building of more than 15 Meter height, planning permit letter and building elevation drawings approved by the competent Local planning Authority should be sent along with the drawing proposal showing the set back clearance, drive way clearance and clearance between the buildings in conformity with the drawings approved by the planning Authority.

3.1.2. Point of supply and Sub-station Layout.

• In case of Outdoor Substation, the following details should be furnished in the drawings.
  • Fencing around consumer’s and supplier’s structure with the location of entrance and the distance between the supplier’s pole and the segregating fence provided for the supplier’s installation from the consumer’s installation.
  • Type and size of poles, pole to pole distance, arrangement of jumpers, AB switch, H.G. fuse, /D.O. fuse. Lightning arresters, supporting channels, jumpers, HT cables, phase to phase clearance, safe working clearance, all round clearance of the Transformers, position of transformer, location and the size of earth leads, oil soak pit and its distance from the substation etc.
  • Distance from the Transformer to the primary and secondary controls.
• Soil resistivity test report, fault level calculation, data and calculation for step and touch potential at the SS yard in the case of Power plant and EHV sub station, protection against lighting, adequacy calculation for the neutral earthing of the transformers, provision of high velocity water jet, nitrogen injection system for the fire protection of transformer should be forwarded.
• In case of Indoor sub-station, the following details should be furnished in the drawings:
  • Location of supplier’s RMG unit with the all round clearance provided for the RMG unit and size of HT cables.
  • Cross-sectional views of the substation building indicating the arrangement of transformer, segregating walls between transformers, distance between the transformers and switch gears, type of roofing, plan, section and elevation of bus duct and its support, ventilation, oil soak pit and its distance from substation etc. with all round clearances.
  • Entrance and exit ways of main panel room, location of main panel and any other switch boards at the main panel room with all round clearances.
  • Details of earthing and cable laying arrangement.

3.1.5. Generator Layout

• Location of the Generators, control panels with all round clearances.
• Plan and section view of the Generator room.
• Clearance between Generator and its control panel.
• Arrangement of exhaust pipe, bus duct and details of earthing arrangement.

3.1.6. O.H. Lines

• Method of construction of the O.H. line, its size and type of conductor material, wih the details of supporting poles, span length, ground clearances, clearance between phases, guarding arrangements, control / protection provided etc., along with the calculation for factor of safety of the supports.

3.1.7. General Observations

• The drawings furnishing all the required details should be clear and legible by proper font size.
• All the drawings should be as far as possible of the same size, uniformly folded to be easily spread-out for scrutiny. They should not be big and unwieldy. Various equipments should be proportionate though not to scale.
• All the drawings should be given numbers and proper headings.
• All relevant information relating to equipments / installation / erection should be given under a suitable note/table/reference in each drawing.
• The connected load on each S.B. and D.B. should be indicated near each board.
• In the lighting distribution, maximum number of points and connected load to each single phase final sub-circuit should be mentioned.
• Anything that cannot be explained by symbols and lines should be clarified with neatly lettered notes or explained as a write up.

3.1.8 Documents to be submitted along with drawings

• An authorisation letter obtained from the consumer authorising the contractor to correspond with the Electrical Inspectorate.
• The drawings should be signed by both the consumer and the Electrical Contractor who is doing the work.
• Check list and Questionnaires for drawing approval should be duly filled-up and signed. Model forms furnished below should be used.

Check List (to avoid rejection at the submission level itself)

Signature of the Consumer (Name)

Signature of the Consumer (Name)

Questionnaire for Drawing Approval