Communication poles, also known as electric poles or telegraph poles, are supporting structures in power or communication line systems. They are usually made of wood, reinforced concrete or other materials and are used to carry and support overhead lines.
Before the 1970s, most of the communication poles used were antiseptic wooden poles. At that time, since the antiseptic treatment of wooden poles was mostly done with asphalt at post offices or long-distance line stations, wooden poles were also commonly called asphalt poles.
After the 1980s, the demand for poles in communication construction has exploded, but the wood for producing wooden poles is limited. At that time, due to the limitation of anti-corrosion technology, the service life of wooden poles was short and the maintenance cost was high. Therefore, cement poles quickly replaced wooden poles in many areas. After that, except for areas with rich log resources, wooden poles were rarely used in new pole lines in other areas.
In recent years, with the increase in labor costs, in mountainous areas or other areas with inconvenient transportation, cement poles are difficult to transport to the location of poles by vehicles. Cement poles are heavy, and manual transportation of poles from sub-stations to the location of poles will incur high transportation costs. Therefore, lighter wooden poles have begun to be used in engineering again.
Introduction to Cement Poles and Wooden Poles
The cement poles used for communication are usually annular concrete poles, and the longitudinal force-bearing steel bars in the poles are prestressed steel bars. The poles are conical in shape, with a taper of 1:75 and a diameter of 150mm.
The tree species used for wooden poles are mostly Pinus sylvestris, Pinus massoniana, Larch and Cunninghamia lanceolata. The requirements for the tip diameter of wooden poles are relatively loose. Usually, the tip diameter of wooden poles with a height of 6.0 meters to 10.0 meters ranges from 12cm to 16cm. There is generally no requirement for the taper of wooden poles.
At present, the anti-corrosion of wooden poles is generally carried out by oil immersion, which is to peel, dry, pressurize and oil-immerse qualified log poles and then air-dry them.
The anti-corrosion oil is usually a mixture of anthracene oil and coal tar. The oil immersion depth of wooden poles is generally not less than 15mm, and the service life is generally not less than 25 years; if the oil immersion depth is insufficient, the service life of the wooden pole will be shortened.
The Difference Between Cement Poles and Wooden Poles in Engineering
- Pole weight and construction difficulty
Taking an 8 meters pole as an example, the weight of a cement pole is about 400kg, while a wooden pole is only 80kg. Since the weight of a wooden pole is much smaller than that of a cement pole, the construction difficulty and cost of a wooden pole are lower.
- Service life
The service life of cement poles is not less than 60 years, and that of wooden poles is not less than 25 years. However, if the material is suitable and anti-corrosion measures are taken properly, the service life of wooden poles may exceed 60 years.
- Pole strength
Theoretically, the bending resistance of wooden poles is much better than that of cement poles, but wooden poles will gradually decay during use. From the perspective of engineering practice, the strength of both pole materials meets the needs of communication construction.
- Product quality consistency
The quality of cement poles is highly consistent, while wooden poles have large differences in tree species, wood defects, pole diameter, weight, etc.
- Fixing of suspension wires and guy wires on poles
Suspension wires are usually fixed on cement poles with clamps and splints, and on wooden poles with nails and splints. Since nailing the suspension wires on wooden poles requires drilling holes in advance, which increases the difficulty of construction, the clamp method is often used to fix the suspension wires in projects.
However, it should be noted that the diameter of wooden poles varies greatly, and the clamp of the appropriate size should be selected according to the diameter of the wooden poles.
The guy wire is usually fixed on the cement pole with a guy wire clamp, and on the wooden pole with a pole guard plate. The wooden pole is not suitable for fixing with a guy wire clamp due to its uncertain taper and soft material.
- Pole price
The price of electric poles varies depending on the region, but the overall difference is not large. In most regions, the prices of cement poles and wooden poles of the same height are similar.
Conclusion and Recommendations
Both cement poles and wooden poles can be used in communication projects. Cement poles have a longer lifespan and high product quality consistency, but they are heavier and are suitable for use in construction sections with convenient transportation.
Wooden poles are lighter and cheaper, and are suitable for use in sections with inconvenient transportation, temporary pole road construction, or areas with abundant log resources. In some areas with very strict requirements for forest pest control, forest management departments may not allow the use of wooden poles.
The quality consistency of wooden poles is poor, and the quality of wooden poles must be carefully checked before construction. However, the inconsistent quality of wooden poles is not an inherent characteristic of wooden poles, but rather the result of operators rarely using wooden poles for so many years and the overly loose index requirements in product standards.
However, the United States still uses a large number of wooden poles for both power and communication lines. Obviously, as long as the product quality requirements are appropriate, the performance of wooden poles can fully meet the use requirements.
As global forest coverage increases, wood is no longer a scarce resource. As labor costs increase year by year, the necessity of using wooden poles in pole line construction is also increasing. If operators impose certain restrictions on the standards of wooden poles when purchasing, the consistency of quality and life of wooden poles can be greatly improved.
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