Question about untility poles...?

Question

How much longer do concrete poles last compared to treated wood poles? Is transmission poles for extra high voltage lines a better investment to be concrete then wood?

Answer 1

Transmission circuits (115 kV and above) use wood poles, steel lattice towers, steel poles, and concrete.

The material used for transmission and distribution poles is somewhat dictated by the environment. For example, Florida and other hot moist climates uses a lot of concrete poles because wood poles would decay too quickly. Termintes and other bugs don't affect the concrete.

In Europe, concrete distribution poles are common. I've even seen ones where the underground cables go up the inside of the pole. In the US a wood pole has the cable runs down the outside of the pole in a conduit or underneath a U-guard.

Concrete poles are VERY heavy and are often produced close to where they are going to be installed. Concrete has excellent compression strength, but is not good for tension or torsional applications. Cross winds and ice loading are the most severe conditions for poles/towers. This can be corrected by building a "pre-stressed" concrete pole with a steel rods that are pre-tensioned" (stretched) while the concrete is hardening. The result is a concrete pole that has good combination of compressive and tension strength.

Steel poles and lattice towers are far more common and generally more economical than concrete. Lattice towers can be field assembled like a giant erector set. Steel poles come in multiple sections that slip on top of one another.

I know of wood transmission poles that have lasted more than 70 years. I don't know how long a typical concrete pole will last.

Composite fiberglass poles are being developed, but have not caught on in the industry yet.

Hope this helps.

Answer 2

There are no concrete poles used in utility power distribution. Those are steel or wood or fiberglass in some instances. This probably so because wood and steel can take shock without fracture as concrete is weak in tension.

The only concrete poles around are used to support a light fixtuture in a parking lot or on freeway exits. And those are re-bar reinforced concrete. Used mainly because of their cosmetic appearance is much more pleasing to the eye that rugged pole or a steel structure as many concrete support poles can be moulded shapes and styled better.