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The usual spans with R.C.C. poles are
40 - 50 m
60 - 100 m
80 - 150 m
200 - 300 m
80 - 150 m
Reinforced Cement Concrete (R.C.C.) poles are commonly used for electrical distribution lines. Their design allows for a structural span of 80 to 150 meters, balancing mechanical strength and cost-effectiveness for low and medium voltage distribution.
Reinforced Cement Concrete (R.C.C.) poles are commonly used for electrical distribution lines. Their design allows for a structural span of 80 to 150 meters, balancing mechanical strength and cost-effectiveness for low and medium voltage distribution.
S=8TwтЛЕl2тАЛ тАФ Sag formula where w is weight per unit length, l is span, and T is tension.
l=w8тЛЕSтЛЕTтАЛтАЛ тАФ Span length derived from the sag-tension relationship.
The span length of a transmission line is governed by the mechanical strength of the pole, the tension in the conductor, and the permissible sag. R.C.C. poles possess high compressive strength and weight, providing greater stability against wind loads and ground forces compared to wood or light steel poles, allowing for longer spans while maintaining a safe clearance from the ground.
R.C.C. poles are preferred for distribution in urban and rural areas due to low maintenance requirements.
The span length is limited by the conductor's breaking load and the pole's bending moment capacity.
Higher spans require larger diameter poles to prevent buckling or fracture under extreme weather conditions.
Longer life compared to wooden poles (low maintenance).
High structural strength and stability against environmental factors.
Good insulating properties.
Very heavy, making transportation and erection difficult without specialized equipment.
Prone to cracks if handled roughly during installation.
High initial cost compared to wooden poles.
Low voltage (LV) and 11kV distribution networks.
Rural electrification projects.
Street lighting distribution systems.
Wooden poles typically allow spans of 40-50 m.
Steel tubular poles can support spans similar to R.C.C. but are prone to corrosion.
Transmission lines (high voltage) use steel towers for spans ranging from 200m to 400m+.
C is correct тАФ R.C.C. poles are designed to support overhead conductors over a standard span range of 80 to 150 meters.
Remember: Sag is directly proportional to the square of the span length (SтИЭl2). As you increase the span, tension must increase or sag will rise beyond safety limits.