A) Rule:60 Where supply line for use at low medium voltage has been disconnected from a system for the purpose of repair, line shall not be reconnected to the system until the supplier or the owner has applied the test prescribed (such as I.R and HV test.)
B) Neutral conductors of 3 phase, 4 wire system and the middle conductor of a 2 phase, 3 wire system shall be earthed by not less than two separate and distinct connections with a minimum of two different earth electrodes or such large number as may be necessary to bring the earth resistance to a satisfactory value both at the generating station and at the sub station. The earth electrodes so provided may be inter connected to reduce earth resistance. It may also be earthed at one or more points along the distribution system or service line in addition to any connection with earth which may be at the consumer’s premises.
C) In the case of system comprising electric supply lines having concentric cables, the external conductors shall be the one to be connected with earth.
D) Where a supplier proposes to connect with earth an existing system for use at high or extra high voltage which has not higher to been so connected with earth, he shall give not less than fourteen days notice in writing together with particulars to the telegraphic authority of the proposed connection with earth.
E) Where the earthling load and earth connection are used only in connection with earthling guards erected under high or extra high voltage overhead lines where they cross a telecommunication line or a railway line and where such lines are equipped with earth leakage relays of type and setting approved by the Inspector the resistance shall not exceed 25 Ohms.
F) If so far as the provisions of rule 61 are consistent with the provisions of this rules, all connections with earth shall also comply with the provisions of that rule.
Rule 69 Pole type sub stations:- Where platform type construction is used for a pole type sub station and sufficient space for a person to stand on the platform is provided, substantial hand rail shall be built around the said platform and if the hand rail, is of metal. It shall be connected with earth.
Provided that in the case of pole type sub station on wooden support and wooden platform the metal hand rail shall not be connected with earth.
Rule 74:- Material and strength :- (1) All conductors of overhead lines other than those specified in sub rule (1) of rule 86 shall have a breaking strength of not less than 317. 51 Kg (700 1bs)
3) Where the voltage is low and the span is of less than 15.24 meters and is on the owner’s consumer’s premises a conductors having an actual breaking strength of not less than 136.08 Kg (300 1bs) shall be used.
Rule- 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 5.791 meters.
b) for high voltage lines 6.096 meters
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 5.485 meters
b) for high voltage lines 5.791 meters
3) No conductor of an overhead line including service lines erected elsewhere than along or across any street shall be at a height less than.
a) for low, medium and high voltage lines upto and including 11,000 volts, if bare 4.572 meters.
b) for low, medium and high voltage lines upto and including 11,000 volts, if insulated 3.963 meters.
c) for high voltage lines above 11,000 volts 5.182 meters.
4) for extra high voltage lines the clearance above ground shall not be less than 5.2 meters plus 0.305 meters for every 33,000 volts or part thereof by which the voltage of the line exceeds 33,000 volts.
Provide that the minimum clearance along or across any street shall not be less than 6.1 meters.
Rule: 78: Clearance between conductors and trolley wires
Rule: 79. clearance from building of low and medium voltage line and services lines.
1) Where a low or medium voltage overhead line passes above or adjacent to or terminates near any building, the following minimum clearance from any accessible point on the basis of maximum sag shall be observed.
2) for any flat roof, open balcony, verandah roof and loan to roof.
Standard
i) When the line passes the building a vertical clearance of 2.439 meters from the nearest point and
ii) when the line passes adjacent to the building a horizontal clearance of 1.219 meters from the nearest point and
iii) for pitched roof:-
i) when the line passes above the building a vertical clearance of 2.439 meters immediately under the line and
ii) when the line passes adjacent to the building horizontal clearance of 1.219 meters.
2) Any conductor so situated as to have a clearance less than that specified in sub rule shall be adequately insulated and shall be attached by means of metal clips at suitable intervals to a bare earthed bearer wire having a breaking strength of not less than 317.51 kg.
3) The horizontal clearance shall be measured when the line is at maximum deflection from the vertical due to wind pressure.
Rule 80: Clearance from building of high and extra high voltage lines:-
1) Where a high extra – high voltage overhead line passes above or adjacent to any building or part of a building it shall have on basis of maximum sag a vertical clearance above the highest part of the building immediately under such line or not less than:-
a) for high voltage lines upto and including 33,000 volts 3.658 meters.
b) for extra high voltage line 3.600 meters plus 0.305 meters for every additional 33,000 volts or part thereof.
2) The horizontal clearance between the nearest conductor and, any part of such building shall on the basis of maximum deflection due to wind pressure, be not less than:-
a) for high volt age lines above 11,000 volts. and up to and including 33,000 volts 1.829 meters.
b) for high voltage, lines upto and including 11,000 volts 1.219 meters
c) for extra high voltage line 1.829 meters plus 0.305 meters for every additional 33,000 volts or part thereof.
Rule 81: Conductors at different voltage on same supports- where conductors forming parts of systems at different voltage are erected on the same supports, the owner shall make
standard
adequate provisions to guard against danger to lineman and other from the lower voltage system being charged above its normal working voltage by leakage from or contact with the higher voltage system and the methods of construction and the clearance between the conductress of the two systems shall be subject to the prior approval of the inspector.
Rule 88: Guarding:-
1) Where guarding is required under these rules the provision of sub rule (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 have an actual breaking strength of no less then 635 kg and if made of iron or steel shall be galvanized.
