What makes Steel Tubular Poles proper choice for Electric Transmission

For carrying of overhead line, wooden poles, concrete poles, steel poles and rail poles are used. Which poles are to be used, depending on the importance of load, location, and place, cost effect of such construction, including maintenance cost, and keeping its profit element in mind. In low voltage line for all phases, natural and earth we use single pole line. 

The load bearing capacity is much more in steel tubular pole in comparison to that of wooden pole and concrete pole. If proper maintenance is done, these poles last for longer period. But due to excessive cost, day by day the use of this pole is gradually decreasing. These poles are used for 400/230 volt low and medium current system. These poles are also used in 11 KV H.T. line. In some cases in can also be used in high voltage like 33 KV system.

There are two types of tubular poles:

Stepped Pole
Swaged Pole

The 1st one is called ISTP and the 2nd one is called ISWP. Both the poles may be cast in one piece of tube or may be cast in the number of tubes and thereafter properly welded together. The Tubular pole should be straight, clean, rust free and defect free. These poles are of different sizes for bearing different load capacities. The gauge of steel pole for H.T. is more, in comparison to L.T. lines. The inside and outside of the pole are to be coated with bitumen up to the length, which is to be grouted under the soil. The remaining length of the pole has to be painted with red oxide. A 14 mm diameter hole is to be made at 300 mm above ground level for earthing purpose. Pole cap is provided in the top of the pole to avoid entrance of rainwater inside.

Following are the reason why steel tubular poles are the best choice for electric transmission

Safety

The steel structures do not require a full length copper grounding wire. They are self conducting for grounding purposes. 

Easy to transport 

Weighing approximately 50-70% less than comparable wood structures, the steel poles are easier and less expensive to handle and install.


Flexibility

Generally steel poles can be customized and fabricated to support larger and heavier loadings with longer spans as well as being able to meet greater height requirements. More options can mean fewer poles to purchase and install. 

Easy-to-Use

The poles can be pre-drilled to accommodate special customer framing requirements and most existing hardware can easily be used on steel structures. Thus making it not only user friendly but also customisable.

Uniformity

Constant taper without twists, knots, splits, or bows provide uniform diameters every time. Steel also has uniform material strength throughout the entire structure providing consistent and predictable results.

Corrosion Protection

A variety of finishes can be given to steel, be it galvanized or painted over galvanized (powder coat or liquid), dulled and darkened galvanizing with below grade coatings. 

Environmental

Steel poles are an answer to EPA regulations and deforestation issues. The poles are non-toxic, which reduce disposal problems or costs and they can be reused or recycled.

Maintenance

After installing steel retains its shape and strength and is nott susceptible to damage by woodpeckers, insects, rot, or fires. There is no expensive inspection and toxic treatment programs necessary after the installation of steel poles. So the maintenance cost is reduced. 

Hot dip galvanized electrical power steel tubular poles plays an important role in electrical power transmission and distribution industry. 
The hot dip galvanization technique could protect steel pole from corrosion for as long as 50 years.