Choosing Between Overhead Insulated Cables and Buried Power Lines

As cities grow and energy demand rises, choosing between overhead insulated cables and buried power lines has become an important decision for urban planners, electrical engineers, and municipal authorities. Each option has clear advantages and trade-offs in terms of installation, safety, reliability, maintenance, cost, and environmental impact. This article explores the differences to help decision-makers select the most suitable solution.

Installation and Setup

How Do Overhead Insulated Cables Work?

Overhead insulated cables are commonly used for power distribution up to 46kV. They are mounted on poles with insulators or spacers, making installation simpler and faster than underground systems. These cables consist of a conductor wrapped in weather-resistant insulation such as polyethylene (PE) or cross-linked polyethylene (XLPE), designed to withstand sun exposure and harsh weather conditions.

Requirements for Buried Power Lines

Installing buried power lines involves excavation, conduit placement, backfilling, and surface restoration. Unlike overhead systems, underground cables must account for soil type, drainage, and existing utilities. This makes them more suitable for high-density urban environments, industrial zones, and areas where aesthetics or safety are priorities.

Ease of Access

Overhead cables are easier to install and repair since workers can use bucket trucks without excavation. Buried cables, however, require trenching for both installation and repairs, which adds time and complexity.

XLPE Insulated Overhead Cable

Safety Considerations

Weather Risks

Overhead cables face exposure to wind, rain, ice, and sunlight. Their insulation—typically black or gray PE or XLPE—is designed to resist UV degradation and weather damage. Buried cables, by contrast, are less vulnerable to environmental factors.

Accidental Damage

Overhead lines can be damaged by falling branches or construction equipment. Proper insulation and spacers reduce this risk. Underground lines are protected from most external hazards but may be accidentally struck during excavation if markings are unclear.

Fire and Public Safety

Overhead insulated cables are generally placed away from buildings and use UV-resistant materials, reducing fire risks. Underground cables present a lower fire hazard but can become dangerous if overloaded or deteriorated with age.

Reliability and Performance

Impact of Severe Weather

Storms can disrupt overhead lines by knocking down poles or trees, even with durable XLPE insulation. Underground cables, protected below the surface, perform better in regions prone to hurricanes, heavy snow, or ice storms.

Temperature Effects

Both cable types expand with heat. Overhead lines benefit from natural air cooling and are typically rated for 75°C to 90°C continuous operation. Underground systems must be engineered according to soil thermal properties, which vary by location.

Maintenance and Repairs

Overhead Cable Repairs

Faults such as burn marks or broken conductors are visible and can be repaired quickly using aerial platforms, resulting in faster service restoration.

Challenges with Buried Cables

Detecting faults in buried cables requires advanced tools like Time-Domain Reflectometers (TDRs). Once identified, excavation is needed, which may disrupt roads, landscaping, or property.

Long-Term Costs

Buried cables require less routine maintenance but are costly to repair when faults occur. Overhead systems need more frequent inspections due to weather exposure, but repairs are generally easier and less expensive.

Lifespan and Durability

Wear on Overhead Cables

Overhead cables use black weather-resistant PVC, PE, or XLPE insulation, which holds up against sunlight but wear out over many years. Regular checks can identify wear before it causes failures.

Buried Cable Protection

Underground cables avoid UV damage but are vulnerable to soil chemistry, moisture, or poor sealing. High-quality seals increase durability but raise initial costs.

Aesthetics and Environmental Impact

Visual Impact of Overhead Cables

Overhead lines can negatively affect scenic landscapes or urban skylines, clashing with architectural or natural surroundings.

Land Use with Buried Systems

Buried lines preserve visual appeal but restrict land use above their routes, limiting large-scale construction or deep-rooted planting.

Cost Considerations

Initial Costs

Overhead systems are more affordable, requiring poles instead of trenches. Materials and installation costs per kilometer are significantly lower than underground networks.

Long-Term Costs

While underground systems involve high upfront investment, they reduce storm-related repair expenses. Overhead lines are cheaper initially but require more frequent inspections and maintenance.

FAQ

Q: What’s the better option for rural areas?
A: Overhead insulated cables are usually more practical in rural settings due to lower installation costs and minimal visual concerns. Long trenching for underground cables quickly becomes uneconomical. However, in storm-prone areas, buried cables may offer better long-term reliability.

Q: Can overhead cables be used near tall trees?
A: Yes, but precautions are necessary. Branches can damage lines, so regular trimming is required, adding maintenance costs. Insulated cables help minimize outages, but in densely wooded areas, underground cables may be the safer option.

About Shenxing Cable

With over 60 years of expertise in the industry, Shenxing Cable, a trusted ABC cable manufacturer since 1979, is committed to delivering high-quality products and solutions. Our company spans more than 122,000 square meters of operational space and holds over 50 patented certifications. Equipped with 16 world-class production lines, we ensure efficient and timely delivery to meet your needs.

If you have any further questions, please feel free to contact us.

Whatsapp: +86-151-2718-0862

Email: sales@sxcables.com

Official Website: www.sxcables.com