Introduction to Underground Infrastructure Safety

In addition to making the appearance of communities more clean, protecting electric cables from weather conditions, and developing modern urban areas and industrial zones with underground utility systems to maintain the functionality of power supplies, communications systems, and data networks; there is a major danger of conducting road work or any other type of construction work in the future. Strikes resulting from accidental contact of shovels, backhoes, and trenchers with buried conduits can lead to large scale power failures, costly repairs, and potential risk to worker safety on site. To reduce the risk of such accidents, engineers place a protective layer (tile) over the conduit that will be buried. This protective layer is generally made from high quality polyvinyl chloride (PVC) material and is called a PVC Cable Tile. The PVC Cable Tile provides a temporary barrier which absorbs mechanical force from construction machinery, notifying excavation crews of the existence of energized electric cables prior to coming into contact with them.

How Polymeric Shielding Outperforms Legacy Materials

In addition, years ago, utility companies used to use either heavy concrete slabs or clay bricks for protecting their underground utilities. The reason utility companies chose these materials for protection was because they thought the weight of the slab would provide the best way to protect the underlying utility line from damage. However, concrete slabs are generally fragile, expensive to transport, difficult to place in tight spaces such as trenches, and have a tendency to fracture due to changes in soil conditions above the slab or as traffic increases over the slab. Polyvinyl chloride (PVC) engineered sheets take a different approach to how trench protection is accomplished at the jobsite. A single worker can easily take several PVC engineered sheets up a trench ladder and attach them together in a short period of time. This significantly decreases labor costs associated with transporting the concrete slabs and decreases fuel costs associated with transporting the concrete slabs. Additionally, unlike cement slabs that break apart when hit by a steel bucket, engineered polymers deflect under pressure and divert impact away from the insulation jacket directly below the polymer sheet.

Essential Structural Properties of Polymeric Cable Covers

How long the electrical grid will function is dependent upon whether the protecting covering applied to the high-voltage feeder and/or fiber-optic cable can withstand environmental factors. The protecting covering made of PVC (polyvinyl chloride) has no electrical conductivity so there is no potential for current flowing through the cable when it rains, when there are repairs being made to the system, etc. Since the protecting covering made of PVC does not deteriorate as quickly as metals do due to deterioration caused by ground water seepage, acids found in soils, oils spilled on the ground, and underground biological decomposition, etc., the protecting covering made of PVC protects the high-voltage feeder/fiber-optic cable from deterioration. Instead of painting on the outside of the protecting covering, the polymers used to create the protecting covering have colorants added to them (e.g., safety yellow, warning red). These colorants provide a long-lasting contrast that can be easily seen after burying the protecting covering for a long period of time. In addition, large, bold, high-contrast lettering printed on the protecting covering provides operators with a clear message regarding the voltage level or type of utility located beneath the protecting covering.

Role of a Specialized PVC Cable Tile Manufacturer

When choosing a PVC Cable Tile Manufacturer for the electrical distribution system in your city/town, your solar power plant, or communication right-of-way; there are many things to consider. One of those things is to find a manufacturer who meets extremely tight tolerances in both dimensions and mechanical properties. Also look for a manufacturer who has a great track record of producing virgin and/or reinforced polymers with high impact resistance, high tensile strength and can handle heavy equipment without buckling. Another thing to consider is whether or not the PVC cable tile manufacturer uses precise extrusion and/or injection molding techniques to produce every single PVC cable tile with the exact same thickness. This will allow for proper locking of the joint connections between the PVC cable tiles. It will also help ensure that the warning messages on each PVC cable tile will last as long as possible regardless of how harsh the environment during construction may be. Finally, you might want to look at whether or not the PVC cable tile manufacturer allows you to dictate the width of each PVC cable tile, allows you to determine how thick you would like each PVC cable tile to be, and/or whether or not they offer custom labeling or multiple languages of warning messages that will comply with your local utility standards and/or International Engineering Standards.

Best Practices for Trench Deployment and Joint Alignment

Properly installed protective plates will form a single continuous armor coating over the top of the conduit(s), as opposed to several separate pieces of un-connected plates. Once the trench has been excavated to the correct depth and a thin layer of screened sand is applied to both sides of the conduit(s), another layer of sand is applied over top of the cables. At this point, the protective covers are laid down flat across the entire width of the trench. The use of either built-in overlapping edges or plastic locking pins can be utilized to prevent the movement of the protective covers due to shifting of the surrounding earth. To ensure no gaps develop between each of the protective covers, which could result in a sharp object penetrating the covers, there must be a minimum of 50 millimeters (mm) of overlap between each unit. After all units have been successfully joined and inspected for any defects, the crew then backfills the remainder of the trench with clean soil and compacts it in multiple layers to provide sufficient support for the walls of the trench.

Industrial and Municipal Sectors Relying on Cable Covers

The use of underground cable protection has many applications, including in civil engineering and industrial construction. For example, electrical utilities place heavy-duty covers on the underground high-voltage and medium-voltage cables (feeders) that run under the city's street system and enter each substation. Telecommunications companies use highly visible warning signs to help prevent fragile fiber-optic cables from being damaged during routine maintenance on water lines or expanding road systems. Many companies that develop large-scale solar arrays or wind farms use lightweight polymeric tiles to protect hundreds of feet of collector cables that have been laid underground in rocky terrain. Companies that use chemical-resistant cable shields can continue to operate in difficult environments like oil refineries, petrochemical plants, railroad tracks, and airport runways.

Conclusion

Investing in protective covers for the protection of underground power/communication cables will help create a safe working environment for your employees, maintain reliability of your operations, and manage your assets effectively over their lifetimes. Protective covers absorb impact much more effectively than traditional concrete covers; they are also lightweight, easily handled, and chemically inert. When you purchase high-quality, properly produced protective covers, you greatly reduce the possibility of experiencing costly interruptions to service, and/or severe employee injuries while working on related tasks within urban and industrial areas. As such, when you combine a well-designed trench with reliable polymeric protective covers, you produce a safer, more sustainable underground system that will provide reliable performance for years to come.

FAQs

Who is the largest supplier of PVC Cable Tile?

Singhal Industries Private Limited has become a leading manufacturer of PVC cable tiles and is currently the world’s most significant supplier of PVC cable tile solutions for underground protection systems. Singhal manufactures custom-engineered underground protection systems for its customers in the United States and other countries around the globe.

How does a PVC Cable Tile protect buried electrical lines?

During the excavation process, a protective, impact-resistant, non-conductive shield is installed over the conduit. This shield is designed to protect the conduit from all types of force applied to the shield as a result of manual and mechanical excavation. In addition, the shield serves as a highly visible and easy-to-read warning system for individuals performing the excavation to alert them that there is potential for damage to the conduit prior to any actual damage occurring.

Can PVC Cable Tiles withstand heavy road traffic and soil pressure?

Yes, the high quality polymeric cables covers are built with a great deal of compression resistance and impact resistance. This allows the cables to resist the pressure created by the large volume of soil that will be placed above the cable once the cable is covered again. Additionally, the cables can withstand the weight of vehicles operating on the road directly above the cable and the weight of other vehicles operating within the industrial yard without sustaining damage.

Why are polymeric cable covers preferred over traditional concrete slabs?

Polymer tile is much lighter than concrete block, which allows for faster transport to the site and placement. Also, polymer tiles can resist moisture and chemicals found in soil and are less likely to crack or fracture than concrete blocks when subjected to physical impact.

Are custom sizes and warning prints available for specific utility projects?

Manufacturer has the potential to modify the size of the tiles (height, width, depth) and allow the customer to select from a range of color codes. Manufacturer also provides the customer with the opportunity to create their own custom warning legend on the top face of the tile, according to the customer's specifications for a particular voltage requirement, and according to the manufacturer's local utility requirements.