What is a Compression Splice? Types and Specifications Guide

A compression splice is a type of electrical connector used in overhead and pole line construction. It is installed on the poles by crimping or compressing it into the conductors using a hydraulic or mechanical compression tool. It is designed to create a permanent, low-resistance electrical and mechanical connection between two sections of conductors. Using compression splices in overhead line construction aids in preventing voltage drops, line losses, or failures. They also ensure reliable performance in high-voltage environments exposed to wind, rain, and temperature extremes. A compression splice offers durability and low electrical resistance and maintains the mechanical strength of the conductor.

Importance of a compression splice in overhead line construction

Splicing techniques are crucial for maintaining electrical continuity and structural integrity across power lines. They provide a low-resistance, secure electrical connection between conductor segments. This is vital to ensure uninterrupted power transmission, reducing voltage drops and supporting efficient current flow in high-voltage systems. The use of compression splices aids in keeping current flowing, withstanding stress from tension, and enabling fast, effective restoration and upgrades. These factors make it a crucial backbone of a secure, high-performance overhead line system. Here is the importance of using compression splices in the electrical infrastructure.

• Restoring mechanical strength—conductors in overhead line systems must withstand tension, wind loading, and thermal expansion. Proper installation of compression splices helps restore full mechanical strength and prevent sagging, snapping, or failure under stress. They help ensure the line stays suspended and stable between poles or towers.
• Repairs and extensions—the splice-on connector allows utility workers to join conductors during maintenance. They extend existing lines without replacing the entire conductor, and reestablish service reliability after damage.
• Withstanding harsh environments—the splices are designed with corrosion-resistant materials. This allows them to perform reliably in extreme weather conditions and resist oxidation, thermal cycling, and mechanical vibration.
• Safety and compliance—industry-approved compression splices are crucial for meeting utility codes and safety standards. They also prevent overheating, sparking, or fire hazards. Additionally, they support load-bearing and electrical performance expected in transmission and distribution systems.

Common materials for splicing techniques

There are several materials used in the construction of compression splices to ensure their safety and durability. The splices ensure a secure mechanical and electrical connection between conductors in overhead line systems. The materials are selected for high conductivity, corrosion resistance, and mechanical strength. Right material selection is crucial for system longevity, safety, and electrical performance. The materials should also be compatible with the conductor, environmental conditions, and expected mechanical loads. Here are the materials for the construction of compression splices.

1. Aluminum and aluminum alloys—these are vital for AAC (all-aluminum conductor), AAAC (all-aluminum alloy conductor), and ACSR (aluminum conductor steel-reinforced). Their key properties include high conductivity, lightweight, corrosion resistance, and compatibility with aluminum conductors to prevent galvanic corrosion.
2. Copper—this is essential for copper conductors in lower-voltage overhead lines or pole-mounted transformer connections. The key properties include excellent electrical conductivity, high resistance to thermal expansion, and durability under electrical load. Copper splices should only work with copper conductors to avoid galvanic corrosion.
3. Copper-aluminum—the bimetallic splices join copper to aluminum conductors safely. Their properties prevent electrolytic corrosion at the junction and provide smooth current transfer between dissimilar conductors. Bimetallic splices are essential in mixed-metal systems.
4. Steel—this material is crucial for reinforcement inside ACSR splices to prevent rust and deterioration. They offer high tensile strength and are functional in the core of the splice to match the mechanical strength of steel-reinforced conductors.
5. Protective coatings and fillers—compression splices include oxide-inhibiting grease, tin-plated finishes, and epoxy seals.

Selecting a compression splice for overhead line construction

The transmission industry is seeing significant advancements in technologies used for overhead line construction. Mechanical splices are crucial for joining conductors and ensuring seamless electrical and mechanical performance. There are various types of compression splices, each designed for specific applications, conductor types, and load requirements. Selecting the right splice depends on the voltage level and mechanical load, the conductor material and size, and the specific installation environment. Below are the common types of compression splices used in pole line construction.

• Full-tension compression splice—these are able to restore 100% of the conductor’s mechanical strength. They serve in high-tension transmission lines. The splices are able to withstand full mechanical load, have hydraulic crimpers, and marked with compression points for proper installation. They mostly work with ACSR and AAAC conductors.
• Non-tension compression splice—these splices ensure electrical continuity with limited mechanical support. They are not designed to carry significant mechanical load and are easier and quicker to install. Non-tension compression splices serve in low-voltage distribution lines and secondary lines.
• Repair compression splices—these are longer than standard splices to cover the damaged area fully. They also provide both electrical and mechanical restoration. They serve in maintenance situations and mid-span conductor damage repair.
• Bimetallic compression splice—they join dissimilar conductors such as aluminum to copper. They are constructed with bonded copper and aluminum sleeves, prevent galvanic corrosion, and maintain proper current flow and integrity. They serve in transitions from utility line to service drop, substations, and mixed-metal installations.
• Dead-end compression splice—these function at the termination point of a conductor and transfer tension to support hardware. These have mechanical strength and provide a secure anchor point for conductor terminations. They mostly work with pole tops, tower ends, and transmission dead deadends.

Splicing techniques supporting renewable energy industries

The world is increasingly transitioning away from the use of fossil fuels towards a cleaner, more sustainable energy future. This transition includes the use of resources such as solar, wind, and hydropower. These renewable resources depend on reliable electrical infrastructure to ensure efficient energy transfer. Compression splices serve in transmission lines from generation sites, interconnecting solar panel strings, wind turbine cabling systems, and underground or overhead power delivery systems. Common splices used in renewable energy systems are from materials such as aluminum, aluminum alloys, copper, and bimetallic splices. The following are the roles of compression splices in renewable energy systems.

1. Solar energy systems—compression splices aid in connecting DC cables from solar panels, joining AC conductors in combiner boxes, inverters, and utility tie-ins. They help in maintaining low-resistance paths for optimal energy yield, reduce voltage drop and line losses, and withstand extreme weather and temperature fluctuations.
2. Wind energy installations—the splices connect conductors within turbine towers and join transmission cables running from turbines to substations. They help ensure strong electrical connection despite tower vibrations and are able to handle high current loads.
3. Hydroelectric power systems—compression splices join heavy-duty transmission cables carrying electricity from generators to substations. They are crucial in both overhead and submerged installations. They are vital components in ensuring watertight, corrosion-resistant connections, maintaining system integrity in high humidity, and delivering reliable power transfer over long distances.

Technical specifications for a compression splice in overhead line construction

Compression splices are able to meet mechanical, electrical, and environmental performance standards. Their specifications vary depending on the type of conductor, voltage class, and application. 

In conclusion

Compression splices function in overhead lines, pole installations, and renewable energy infrastructure. They ensure mechanical integrity, electrical continuity, and system reliability in environments exposed to weather, vibration, and high electrical loads. The splicing techniques maintain electrical flow by reducing resistance at conductor joints, provide mechanical strength, enable safe transitions, and ease repairs and scalable installations in power lines. They are essential in ensuring electrical reliability, mechanical strength, and scalability across modern energy networks. They are crucial in ensuring reliable connectivity, supporting smart infrastructure, reducing downtime, and enhancing load handling. Additionally, they enhance efficient transmission, flexible installation, corrosion resistance, and mixed conductor compatibility in renewable energy systems.

Catalog

Compression splices are essential enablers of the next-generation power grid. They provide durable, low-resistance, and scalable connections to support the integration of renewable energy and modernization of legacy infrastructure. Common types of compression splices include full tension, non-tension, repair sleeve, bimetallic, reducer, and dead-end splices. The type selected depends on the specific material used and technical specifications.

At TTF Power, we are a one-stop shop for utility pole hardware fittings, transmission line accessories, and power line construction equipment. We provide our customers with the most extensive range of products in the industry, excellent value, and knowledgeable service. TTF is a world-class global provider of high-quality overhead line hardware, transmission hardware, distribution hardware, conductors, insulators, cutout switches, and anchoring and grounding products.  TTF aims to fill the overseas utility industry with affordable and high-quality power hardware. This is as a distributor-level direct export supplier of overhead line hardware, power pole accessories, conductors, and a series of power transmission and distribution line accessories.  Subscribe to our newsletter for weekly updates related to transmission products, energy, and electrical news.