Indian Electricity Rules

Rule 77: Clearance above ground of the lowest conductor:

   (1) No conductor of an overhead line, including service lines, erected across a street shall at any part thereof be at a height less than-
        (a) for low and medium voltage lines  5.8 metres
        (b) for high voltage lines                   6.1 metres

   (2) No conductor of an overhead line, including service, lines, erected along any street shall at any part thereof be at a height less than-
        (a) for low and medium voltage lines  5.5 metres
        (b) for high voltage lines                   5.8 metres

   (3) No conductor of an overhead line including service lines, erected else- where than along or across any street shall be at a height less than-
        (a) for low, medium and high voltage lines up to and including 11,000 volts, if bare ;     4.6 metres
        (b) for low, medium and high voltage lines up to and including 11,000 volts, if insulated 4.0 metres     4.0 metres
        (c) for high voltage lines above 11,000 volts     5.2 metres

   (4) For extra-high voltage lines the clearance above ground shall not be less than 5.2 metres plus 0.3 metre for every 33,000 volts or part thereof by which the voltage of the line exceeds 33,000 volts:
     PROVIDED that the minimum clearance along or across any street shall not be less than 6.1 metres.

Rule 79. Clearance from buildings of low and medium voltage lines and service lines:

   (1) Where a low or medium voltage over-head line passes above or adjacent to or terminates on any building, the following minimum clearances from any accessible point, on the basis of maximum sag, shall be observed:-
        (a) for any flat roof, open balcony, verandah roof and lean-to-roof-
            (i) when the line passes above the building a vertical clearance of 2.5 metres from the highest point; and
            (ii) when the line passes adjacent to the building a horizontal clearance of 1.2 metres from the nearest point, and

      (b) for pitched roof-
        (i) when the line passes above the building a vertical clearance of 2.5 metres immediately under the lines, and
        (ii) when the line passes adjacent to the building a horizontal clearance of 1.2 metres.

   (2) Any conductor so situated as to have a clearance less than that specified in sub-rule (1) shall be adequately insulated and shall be attached suitable intervals to a bare earthed bearer wire having a breaking strength of not less than 350 kg.

   (3) The horizontal clearance shall be measured when the line is at a maximum deflection from the vertical due to wind pressure.

[Explanation-For the purpose of this rule, expression "building" shall be deemed to include any structure, whether permanent or temporary .]

Rule 87:Lines crossing or approaching each other:

   (1) Where an over-head line crosses or is in proximity to any telecommunication line, either the owner of the over-head line or the telecommunication line, whoever lays his line later, shall arrange to provide for protective devices or guarding arrangement, in a manner laid down in the Code of Practice or the guideline prepared by the Power and Telecommunication Co-ordination Commitee and subject to the provisions of the following sub-rules.

   (2) When it is intended to erect a telecommunication line or an over-head line which will cross or be in proximity to an over-head line or a telecommunication line, as the case may be, the person proposing to erect such line shall give one- month ' s notice of his intention so to do along with the relevant details of protection and drawings to the owner of the existing line.

(3) Where an over-head line crosses or is in proximity to another overhead line, guarding arrangements shall be provided so as to guard against the possibility of their coming into contact with each other. Where an over-head line crosses another over-head line, clearances shall be as under :

[Minimum clearances in metres between lines when crossing each other

S.No Nominal System Voltage 11-66 KV 110-132KV 220KV 400KV 800KV
1. Low and medium 2.44 3.05 4.58 5.49 7.94
2. 11-66 KV 2.44 3.05 4.58 5.49 7.94
3. 110-132KV 3.05 3.05 4.58 5.49 7.94
4. 220KV 4.58 4.58 4.58 5.49 7.94
5. 400KV 5.49 5.49 5.49 5.49 7.94
6. 800KV 7.94 7.94 7.94 7.94 7.94]

PROVIDED that no guardings are required when an extra-high voltage line crosses over another extra-high voltage, high voltage, medium or low voltage line or a road or a tram subject to the condition that adequate clearances are provided between the lowest conductor of the extra-high voltage line and the topmost conductor of the overhead line crossing underneath the extra-high voltage line and the clearances as stipulated in rule 77 from the topmost surface of the road is maintained.]

(4) A person erecting or proposing to erect a line which may cross or be in proximity with an existing line, may normally provide guarding arrangements onhis own line or require the owner of the other over-head line to provide guarding arrangements as referred to in sub-rule (3).

(5) In all cases referred to in the preceding sub-rules the expenses of providing the guarding arrangements or protective devices shall be borne by the person whose line was last erected.]

(6) Where two lines cross, the crossing shall be made as nearly at right angles
as the nature of the case admits and as near the support of the lower line shall not be erected below the upper line:

[PROVIDED that the angle of crossing of power lines shall not be less than 600.]

(7) The guarding arrangements shall ordinarily be carried out by the owner of the

supports on which it is made and he shall be responsible for its efficient maintenance.

(8) All work required to be done by or under this rule shall be carried out to the satisfaction Inspector.

Rule: 88. Guarding:

(1) Where guarding is required under these rules the provisions of sub-rules (2) to (4) shall apply.

(2) Every guard-wire shall be connected with earth at each point at which its electrical continuity is broken.

(3) Every guard-wire shall be an actual breaking strength of not less than 635

(4) Every guard-wire or cross-connected system of guard-wires, shall have sufficient current-carrying capacity to ensure the rendering dead, without risk of fusing of the guard-wire or wires till the contact of any live-wire has been removed.

(5) Lines crossing trolley-wires-In the case of crossing over a trolley-wire the guarding shall fulfill the following conditions, namely:-

        (a) where there is only one trolley-wire, two guard-wires shall be erected as in diagram A;

        (b) where there are two trolley-wires and the distance between them does not exceed 40 cms., two guard-wires shall be erected as in diagram B;

        (c) where there are two trolley-wires and the distance between them exceeds 40cms. but does not exceed 1.2 metres, three guar-wires shall be erected

        (d) where there are two trolley-wires and the distance between them exceeds 1.2 metres, each trolley-Wire shall be separately guarded as in diagram

        (e) the rise of the trolley boom shall be so limited that if the trolley leaves the trolley-wire, it shall not foul the guard, wires ; and

        (f) where a telegraph-line is liable to fall or be blown down upon an arm, stay -wire or span-wire, and so slide down upon a trolley-wire-, guard hooks shall be provided to prevent such sliding.

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