The most common methods are direct burial and laying cables in ducts or conduits. Direct burial is cost-effective but makes future repairs or upgrades difficult. Cables are placed directly into a trench, surrounded by a protective layer of sand and covered with mechanical protection. Laying cables in ducts or conduits provides greater mechanical protection and allows for easier maintenance and replacement of cables without the need for re-excavation. We manufacture a full line of equipment for both methods.
Specialized equipment is essential for a safe and efficient installation. Cable drum jacks and trailers are used to lift and support the heavy cable drums. Cable rollers are placed in the trench to guide the cable smoothly around bends and over the length of the run, preventing damage from friction and kinking. Hydraulic winches are used for pulling the cable through ducts or long trenches, with tension monitoring systems to ensure the force applied does not exceed the cable's maximum pulling tension, thereby protecting its integrity.
Post-installation testing is crucial to verify the integrity and safety of the cable. We recommend conducting key tests before energization, including insulation resistance testing to check for electrical leakage and high-potential (Hi-Pot) testing to assess the cable's ability to withstand high voltage. For locating faults after installation, tests like the Murray Loop test can be used to pinpoint the exact position of a fault without extensive digging.
Safety is paramount. Key considerations include:
-
Personal Protective Equipment (PPE): Ensuring all personnel wear appropriate gear, including safety helmets, insulated gloves, and shock-proof boots.
-
Equipment Safety: Using only insulated and tested tools and ensuring all machinery, such as winches, has safety features like breakaway links or tension monitors.
-
Site Management: Following strict procedures for excavation near existing utilities, implementing Lockout/Tagout (LOTO) procedures, and using warning signs and barriers to protect workers and the public.
A successful cable laying project follows a systematic process. The key stages include:
-
Planning & Design: Thorough route inspection, engineering calculations for pulling tension and sidewall pressure, and obtaining all necessary permits.
-
Site Preparation: Excavation of trenches or installation of cable trays and conduits.
-
Cable Installation: The actual laying and pulling of cables using specialized equipment such as winches, rollers, and drum jacks to ensure the cable is not overstressed.
-
Termination & Jointing: Making secure connections at switchgear, panels, and other equipment.
-
Testing & Commissioning: Post-installation tests like insulation resistance (IR) and high-potential (Hi-Pot) testing to verify the cable's integrity before it is energized.
To prevent cable damage, it is crucial to adhere to specific best practices. This includes using specialized cable rollers to reduce friction and kinking, maintaining the cable's specified minimum bending radius at all times, and applying suitable lubricants. Most importantly, a tension monitoring system must be used with a pulling winch to ensure that the maximum pulling tension is never exceeded, which can stretch or damage the cable's insulation and conductors.
The primary standard is IEC 60364, specifically Part 5-52, which covers the "Selection and erection of wiring systems." This standard provides comprehensive international guidelines for the safe design, installation, and verification of low-voltage electrical installations. It is a foundational document that many national codes are based on, ensuring global consistency in safety and quality.
The IEC standard provides guidelines on installation methods, but specific requirements for burial depth and separation are often subject to national and local regulations, which are typically stricter. The standard's core principle is to ensure adequate protection against mechanical damage, thermal effects, and potential hazards. This involves using appropriate protective measures like cable tiles, warning tapes, and sand bedding, which we recommend and can provide equipment for.
The standard addresses cable sizing to prevent dangerous thermal effects. It specifies the methods for calculating the current-carrying capacity of a cable based on various factors, including the type of installation (e.g., buried directly in the ground, in ducts, or in air), ambient temperature, and the number of cables in a group. Our equipment, such as hydraulic crimping tools and cutters, is designed to handle a wide range of cable sizes, ensuring compliance with these technical requirements.
There are several types of machines, each designed for specific project requirements. Cable pulling winches are widely used for pulling cables through pre-installed ducts or conduits, especially over long distances. They are ideal for projects that require a high degree of control over pulling force and speed. Cable plows are trenchless machines that bury cables directly into the ground, making them highly efficient for rural or open-field projects with minimal obstacles. Trenching machines are used to dig open trenches, which is suitable for urban areas or projects where the soil condition is hard and requires a precise, visible path for cable installation.
When selecting a winch, consider features that ensure safety, efficiency, and reliability. Variable speed and tension control are critical for preventing damage to the cable. Data logging systems are a trendy feature that allows for real-time monitoring and recording of pulling tension, which is essential for quality control. Other important features include a robust braking system, a large wire rope capacity, and a durable, compact design that is easy to transport and set up.
The integration of automation technologies like Programmable Logic Controllers (PLCs) and Human-Machine Interfaces (HMIs) significantly enhances the efficiency and safety of cable laying. PLCs allow for precise and automated control of the pulling process, adjusting speed and tension in real-time based on sensor feedback. HMIs provide operators with a user-friendly interface to monitor and manage the operation, reducing the risk of human error. This technology can also enable remote control and monitoring, which is a key advantage for modern construction.
The air blown fiber (ABF) method is a modern technique where a jetting machine uses compressed air to install a lightweight fiber optic microcable into a pre-installed microduct. The primary advantage of this method is the reduction in tensile stress on the delicate fiber optic cable during installation, which minimizes the risk of damage. It's also significantly faster for long distances, more cost-effective due to less labor and smaller equipment, and provides future-proof scalability as you can install empty ducts and blow in more fibers later as demand increases.
Micro-trenching is a minimally invasive technique that uses a cutting wheel to create a narrow, shallow groove in the pavement, sidewalk, or street. This method is highly favored in urban settings because it significantly reduces surface disruption and traffic interference compared to traditional trenching. The small size of the trench allows for quick installation and restoration, making it an efficient and less disruptive solution for busy city environments.
The primary challenges include dealing with complex geographical terrains (e.g., rocky or mountainous areas), navigating existing infrastructure in urban environments, and ensuring the delicate cable is not damaged by excessive pulling force or tight bends. Using specialized equipment such as hydraulic pulling machines with precision tension monitoring and control systems helps overcome these challenges. Additionally, employing advanced methods like horizontal directional drilling (HDD) allows for trenchless installation under obstacles, and using robust cable plows is effective for direct burial in less congested areas.
Cable laying machines can be broadly categorized based on their application and technology. The main types include cable pulling winches for overhead transmission lines and underground ducts, which use force to pull cables through a path. For direct underground burial, cable plows are used, which create a trench and simultaneously lay the cable. In manufacturing, laying-up machines are used to twist multiple insulated cores into a single cable. Our product range offers solutions for overhead, direct burial, and duct-based installations, ensuring the right tool for every project.
Modern machines are designed with automation and operator safety in mind. Key features to look for include PLC control systems for precise synchronization and operation, automatic tension monitoring to prevent damage to the cable during pulling, and variable frequency drives for slow starts and controlled stops. Additionally, machines with a cradle-type design or vertical structure are trending for handling large, heavy cables, while advanced hydraulic systems offer superior control and power.
Cable laying machines dramatically improve efficiency by reducing the reliance on manual labor, which in turn shortens project timelines and lowers labor costs. Their precision ensures accurate cable placement, minimizing the need for costly corrections. Automated features, such as integrated GPS and remote controls, further streamline the installation process. These efficiencies translate to a higher quality outcome and a significant return on investment.
The choice of installation method depends on the project's specific conditions, including terrain, urban density, and budget. The most common methods are:
-
Micro-trenching: This method involves cutting a narrow, shallow trench (typically 1-2 inches wide and 12-24 inches deep) in the road or pavement, laying the cable or micro-duct, and then sealing the trench. It is a fast, cost-effective, and minimally disruptive method ideal for urban areas with existing hard surfaces.
-
Horizontal Directional Drilling (HDD): This trenchless method uses a steerable drill to create a bore path under obstacles such as roads, rivers, or existing utilities. It is a preferred method for complex projects or environments where surface disruption must be avoided.
-
Plowing/Direct Burial: Using a vibratory plow, this method quickly buries the cable directly into the ground without the need for a pre-dug trench. It is highly efficient for rural or open areas with soft soil.
Our comprehensive range of equipment, including hydraulic cable pullers and cable laying equipment, is designed to support all these methods, ensuring efficient and safe installation regardless of the terrain.
Underground installation presents several challenges, which require careful planning and specialized equipment:
-
Navigating Existing Infrastructure: Urban areas have a complex network of existing utilities (water, gas, electricity). Detailed site surveys using tools like Ground-Penetrating Radar (GPR) are essential to map out underground obstacles and prevent accidental damage during drilling or trenching.
-
Terrain and Soil Conditions: Rocky terrain, hard surfaces, or high water tables can make traditional trenching difficult and time-consuming. Using methods like HDD or specialized plowing equipment is crucial in these conditions.
-
High Installation and Repair Costs: While underground cables are more secure, the initial installation can be expensive due to the required excavation and specialized equipment. Additionally, repairs are labor-intensive and costly. Using durable, high-quality conduit and robust cable installation techniques from the outset can significantly reduce future maintenance and repair costs.
