Line Supports, Types of Electrical Poles Overhead Transmission Lines
We know most of the electrical power is distributing by overhead transmission lines. We have
electrical poles to transmit and distribute the different range of voltages by different types of
electrical poles.
Types of Line Supports or Electrical Poles
Different types of poles or towers are used to support overhead lines structures which are known
as line supports.
A line support should possess the following requirements.
(i) It should have the high mechanical strength to bear the conductor weight, wind load etc.
(ii) Maintenance should be easy and cost should be very low.
(iii) It Should be very light in weight and extremely durable.
(iv) Proper spacing between the conductors and ground clearance must be maintained.
The different line supports used by transmission lines include,
(a) Wooden Poles





shorter spans about 50 meters
suited for rural areas
withstand voltage up to 132 kV
higher transverse strength
used for terminal poles.
b) Reinforced concrete poles



longer durability
used for system 33 kV
longer spans, longer- life
(c) Steel poles





voltages up to 33 kV (low and medium voltages)
high mechanical strength
longer life of at least 30 years
lightweight but are costlier
maintenance cost is high
d) Latticed steel towers.





used for long-distance transmission
voltages above 33 kV
longer-life
high mechanical strength
withstand severe climatic conditions
Types of steel tower


Self supporting tower
Narrow base lattice type
- used for shorter spans.

Broad-base towers.
- span is very large
2. Stayed or guyed towers
-preferred in USA and Canada
-Less expensive
- lighter
The choice of support depends upon the cost, span of line, atmospheric conditions and line
voltage.