There are two methods of installing the power lines that carry electricity to your home, overhead and underground. San Patricio Electric Cooperative members sometimes ask why we use one versus the other, or more to the point, why all power lines are not installed using the underground construction method. Isn’t one method better than the other? These are great questions, and the answer is that each method has its place.

Let’s take a look at some the advantages and disadvantages of each construction method, beginning with overhead.

Overhead construction

Overhead line construction starts with the setting of utility poles. Poles can be set in nearly any type of terrain, even rocky. In the case of heavy rock, special equipment is used to augur out the hole. If placement occurs in boggy or wet terrain, many techniques are available to set poles securely. Once the poles are in place, wires can be strung and then equipment––like transformers, fuses and reclosers­––are installed.

Pros:

• Lower cost. Overhead power lines are a less expensive way to get power to your home. They are also less expensive to repair and upgrade.
• Quicker construction. Overhead lines can be installed relatively quickly, since there’s no need to trench.
• Easier to spot damage and faults. Our linemen can see the entire line when its placed overhead, which makes it easier to spot outage causes or potential problem areas.
• Can be built anywhere.
• Any voltage can be placed overhead.

Cons:

• More susceptible to bad weather, such as high winds.
• More vulnerable to damage from trees and vegetation, which requires right of way trimming.
• Vulnerable to blinks when animals and branches contact lines.
• Susceptible to damage from vehicle collisions.
• Less attractive.

Underground construction

Underground line construction requires digging a trench that is deep enough to keep the lines well away from surface activities. Where the terrain is extremely rocky, underground lines may not be an option. Next, wires are laid in the trench directly or placed in conduits for protection. The trench is filled in, and the surface is restored to its original condition. Padmount transformers and additional equipment are installed as needed.

Pros:

• Not vulnerable to damage from tree branches; no right of way trimming required.
• Less susceptible to damage from vehicle collisions
• Not impacted by wind
• Less vulnerable to blinks when animals and branches contact lines.
• More attractive. Some people choose to install underground power lines so the infrastructure doesn’t obstruct their view.

Cons:

• More expensive to build and repair
• Fed by overhead lines. At some point, all underground power lines are connected to overhead lines, which makes them vulnerable to outages.
• Susceptible to flooding
• Difficult to locate faults
• Limitations on voltages that can be buried underground.
• Can be vulnerable to dig-ins. Make sure you always call 811 to locate underground utilities before you dig.

Determining if power lines should be overhead or underground boils down to what is best for the situation. Underground lines might be ideal in situations where there is a desire to keep the poles and wires out of sight, such as a residential neighborhood, park or historical area. There are many cities and towns that construct only underground lines for a variety of reasons.

Overhead systems work well when appearance is not a major concern. Examples include extremely long line distances across country, and where the voltages are higher than the limitations set for underground lines.

The ultimate mix of underground and overhead construction used by SPEC provides you, our members, with the highest possible quality of service at the lowest possible price. Cost, appearance, reliability, maintenance and future upgrades will drive which is the better approach, overhead or underground.