17 April 2019

Minimum Clearance Between Transmission Line Conductor And Ground

The minimum distance between transmission line conductor and ground is given as per Indian Electricity rules 1956 is given as below.

Clearance between lowest conductor of the transmission line and ground

  • The overhead line conductors including service lines do not erected across street at height less than

Low and medium voltage
5.8 meters
High voltage
6.1 meters

  • The overhead line conductors including service lines do not erected along any street at height less than

5.5 meters
5.8 meters

  • The overhead line conductors including service lines do not erected elsewhere than along or across any street at height less than

Low, medium and high voltage lines up to and including 11 kV      ( bare conductor )
4.6 meters

Low, medium and high voltage lines up to and including 11 kV      ( Insulated conductor )

4.0 meters
High voltage lines above 11 kV

5.2 meters

Extra high voltage transmission lines
5.2 meter + 0.3 meter per 33 kV ( The minimum clearance along or across any street should not be less than 6.1 meters )


Clearance between conductors and trolley wires

Low and medium voltage
1.2 meters ( When insulated conductor suspended with wire crosses over a trolley wire, the minimum clearance should be 0.6 meter )
High voltage line up to 11 kV

1.8 meters
High voltage line above 11 kV – 2.5 meters

2.5 meters
3.3 meters

Clearance from building of low and medium voltage lines and service lines

  • Low or medium voltage line passes above or adjacent to any building, the minimum clearance should be

Flat roof, veranda roof, leans to roof and open balcony

When line passes above building
Vertical distance of 2.5 meter from highest point of building
When line passes adjacent to the building
Horizontal clearance of 1.2 meters from nearest point of building

Pitched roof ( Roof with slopping surface with angle > 20 degree )

When line passes above building
Vertical distance of 2.5 meter immediately under the lines
When line passes adjacent to the building
Horizontal clearance of 1.2 meters

  • If any conductor situated as to have a clearance less than the specified shall be proper insulated and shall be attached at suitable interval to bare earthed bearer wire having breaking strength not less than 350 kg.
  • The horizontal clearance is measured when line is at maximum deflection from vertical due to wind pressure.

Clearance from building from high and extra high voltage

  • When high voltage or extra high voltage passes adjacent or above the building, the vertical distance between highest points of tower is calculated by considering sag in the lines. 
  • The distance between highest point of the building and line should not less than

High voltage up to and including 33 kV
3.7 meters
Extra high voltage lines
3.7 meter + 0.30 meters per additional 33 kV

  • The horizontal distance between any building and transmission line considering maximum deflection due to wind pressure should not be less than

High voltage up to and including 11 kV
1.2 meters
High voltage line above 11 kV and up to 33 kV
2.0 meters
Extra high voltage lines
2.0 meters + 0.3 meters per additional 33 kV


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