Structural Support

The pros and cons of power pole options

Power poles are part of the landscape and are usually taken for granted. But they have a powerful purpose.

Whether wood, laminate wood, metal, concrete or composite fiberglass, poles are the structures to which transmission and distribution lines and transformers are attached. Working together, the system carries electricity to residences and businesses, powering lamps to refrigerators in homes and complicated computer systems to robotic machines for multimillion-dollar companies.

Using a pole for transmission came about in 1843 after Samuel Morse’s demonstration project to send messages over a distance via underground telegraph wires proved ineffective. It was suggested the quickest way to complete the project would be to string telegraph wires overhead using wood poles. While the telegraph system eventually faded away, wood poles did not. They were there to provide the needed structure when electrical systems came on line.

For many decades, wood poles—whether from Douglas fir or cedar trees harvested in the Pacific Northwest, or yellow pine trees from the southern U.S.—had no competitors in providing structure for electrical wires, transformers, insulators and fuses. But that has changed with laminate wood, steel, composite fiberglass and concrete poles becoming options in recent decades.

Because wood poles have the longest history and the electrical industry has been traditionally conservative regarding change, wood is still the most popular option. But depending on conditions, other types of poles are being put into operation.

“Experimentation of the different poles is ongoing,” says Brent Hill, vice president of sales for General Pacific, a company that provides products and services to the electrical industry. “Everybody is looking for structures that can withstand whatever Mother Nature has to offer, but I’ve read articles indicating they are all still susceptible to Mother Nature.”

Following are the pros and cons for each of the different power pole options.

Wood

Wood poles are plentiful, renewable and the industry is most familiar with them. The life span of a treated wood poles is 30 to 40 years, but some that are 50 to 60 years old are still in good shape.

Pros:

• Easy to work with and easy to work on.
• Can be climbed by linemen and drilled to add attachments.
• Utilities already have the tools and equipment needed to work on the poles and to maintain them.

Cons:

• Susceptible to fire—especially if treated with a chemical preservative, which most are.
• Some people consider poles treated with a preservative not to be environmentally friendly because rainwater and groundwater can carry the preservative into nearby ground or the water system.
• Testing for deteriorating or rotting wood at the base or in the ground is required on a 5- to 10-year rotation, depending on location. Testing is needed more frequently in wet or coastal terrain than in a drier climate.
• Wood absorbs moisture. In freezing weather, poles can become brittle and susceptible to breaking in windstorms or when hit by falling branches or trees.
• Wood poles can be weakened by woodpeckers.

Laminate Wood

These poles are made from wood boards pressed and glued together under extreme pressure. They receive a preservative treatment after lamination. They have lasted more than 50 years.

Pros:

• Because of their tremendous strength, these poles are generally used where there is no room for guy wires, but the utility wants to use wood.
• The pole can be climbed and drilled using the same tools as on traditional wood poles. However, working from a bucket truck is preferred.

Cons:

• Heavier and more expensive than wood.

Steel/Metal

The second most popular, these poles are one of the strongest options. They are hollow, with about a quarter-inch of metal forming the exterior, and are usually several-sided rather than circular. They have an estimated life span of 60 to 80 years.

Pros:

• Being hollow, these poles are not too heavy.
• When erected correctly and in the right terrain, most do not need guy wires.
• Because they don’t need a preservative treatment, they are environmentally friendly.
• In coastal and salty environments, steel lasts longer than wood.
• Steel doesn’t need the maintenance and routine testing of wood. Visual condition checks usually are sufficient.
• They stand up better against strong winds.
• Steel is fire resistant.

Cons:

• Steel is more expensive than wood.
• Adding attachments to steel poles is more difficult than wood because welding or drilling on steel is difficult. It’s best if the steel is pre-engineered for attachments before the pole goes in the ground.
• Climbing steel is a challenge, so it is best if the pole is accessible to bucket trucks. If not, steps or ladders can be used to access the top of the pole.
• Steel is more conductive than other pole options, so it can be detrimental to work crews and wildlife if the system on the pole is not in the best of shape and becomes energized.
• If hit by a vehicle, the strength of the pole is significantly impacted because it is hollow.

Composite

These poles can be made from a combination of materials, with the most prevalent being produced from a mixture of fiberglass and polyurethane resin. Plastics, reclaimed wood or medium-density fiber also can be used. Their longevity is estimated to be 60 to 80 years.

Pros:

• The lightest of the options, it still has strength that exceeds wood.
• Fiberglass is environmentally friendly. When used in a wet environment, there is no leeching of preservative.
• These poles can come in sections, making them easier to move and handle, even by hand in rough terrain.
• Drilling is possible using the same equipment used on wood.
• Maintenance is not extensive.

Cons:

• Composites are more expensive than wood.
• These poles are being monitored and tested for how they react to fire. They don’t seem to hold up well, but can be treated with or manufactured with a fire-resistant product.
• Manufacturing composites requires more energy than milling and treating a wood pole, according to the Environmental Literacy Council.

Concrete

Reinforced concrete poles have become popular as line supports. They permit longer spans of line between poles, and have a life span of 60 to 80 years.

Pros:

• Strength.
• They take little maintenance.
• They have good insulating properties.

Cons:

• The weight of these poles make them difficult and expensive to move. When used, they are usually manufactured on site.
• Few utilities in the West have the equipment to deal with these poles and to drill them, if needed, after they are upright.
• They can’t be climbed unless holes or steps in the concrete have been pre-engineered. Otherwise, a bucket truck must be able to reach them.
• If they are knocked over by some event, they will do major damage to nearby structures and are difficult to clean up.