Lightning arrester : –
A system provided at the highest point of a structure to protect it from lightening is known as ‘lightening arrester’. The lightening arrester shall be necessarily provided for the buildings situated at remote and hilly areas.
Material Required: –
- Copper tape conductor, 25mm x
- Solid copper rod having upper terminal of 90mm diameter and of length 1.5m, with a knob at the end with a conical spike on
- Suitable clamps to fix the conductor to
- Copper earth plate 1.5mm thick and 1m2 in
- Charcoal and sand for filling the earth
- I. pipe of 60mm diameter including fittings confirming to I.S.1230-1968.
Work Procedure: –
- The upper terminal shall be fixed vertically at the highest point on the The terminating cone on the knob shall have a height equal to the radius of its base.
- The conductor tape shall be attached to the upper terminal at the lower end by double riveting and soldering. It shall be fixed along the building face from outside, exposed to
- The conductor shall preferably be in one piece and shall be straight as far as
- If required to be bent, the straight length between the ends of bends shall not be less than half the curved
- The conductor shall be enclosed in a 60mm diameter cast iron pipe fixed on the wall, for a height of 3m from ground to protect the conductor from injury/theft.
- All metal surfaces, ridges, grooves gutters, etc shall be connected to the conductor with metal After thorough cleaning and roughening by sand paper the copper rod and tape shall be fixed with screw or rivet and in addition it shall be soldered.
- The lower end of the conductor shall be carried to a depth of 1.0 m below the
- Necessary trenches and pits shall be excavated for laying of the conductor and the copper
- The trenches shall be 10 to 13m long and 1m deep and shall be 5 to 6m away from the
- A copper tape of 25mm x 3mm shall be riveted and saddled to the lower end of the conductor and carried along the trench up to the spot where the copper plate is to be
- The other end of the tape shall be connected to the copper earth plate by riveting and
- All the joints from the upper end of the top terminal to the earth plate shall be perfect, mechanically and electrically.
- The copper plate shall be ensured to be at a 60 m to 1.0 m below the substrata water level in the driest season of the year.
- Where the permanent subsoil water level is deep, it is necessary to provide shallow earth in trenches laid away from the The thickness of the layer of the earth to be spread shall be 30 cm in dry soil and 60 cm in sandy soil. This layer helps to percolate the rain water easily.
- The length of the trench shall be between 10m to 13m in dry soil. Alternatively conductor tape may be attached to a copper plug suitably riveted and
- This plug shall then be inserted into a water supply pipe by coupling or tee
- The earth plate shall be surrounded with
- The copper conductor shall be laid in charcoal and the trench filled with
- The surface water shall be directed towards the
- Copper tape and rod should not be
Testing Of Lightening Conductor: –
- The lightening conductor shall be tested for the resistance by suitable The overall resistance of the complete conductor system from the arrestor to the earth should be about 1 to 2 ohms.
- The overall resistence should not exceed 10
- If the results are beyond the above limit, the defects shall be rectified so as to get satisfactory