Whether it’s electricity, telecommunications, or other utilities, they all need to bury cable. Properly burying cables not only maintains the aesthetic of your outdoor space but also safeguards the lines from potential damage. However, burying cables is not as simple as digging a hole and covering them up. It requires meticulous planning and approaches to ensure safety and effectiveness. We’ll take you through the steps to effectively bury your cables underground.
Step 1: Gather the Necessary Tools
To Lay the underground wiring, you will need the following tools:
Trenching tools: Shovel, pickaxe, or other electric trenching tool for for digging ditches where cables are laid.
Tape measure: to measure trench depth and length.
Cable clamps: Secure cables to keep them neat and prevent the underground electrical wire from tangling or hanging loose.
Cable conduit and fish tape (optional): The conduit provides additional protection for the cable, especially where the cable may be physically damaged or exposed to moisture, while the fish tape is used to pull the cable through the conduit.
Cable lubricant (if using conduits): Reduces friction when pulling cables through conduits, making the process smoother.
Warning tape: used to indicate buried cable.
Step 2: Plan Your Route
It is essential to plan the route of cables before you start digging. In many countries, the law mandates contacting local utility companies or relevant authorities before digging to avoid damaging existing underground services like power lines, gas mains, water pipes, and telecom cables. In the U.S., for example, you can dial 811. Additionally, The ideal cable path is to utilize straight segments wherever feasible, avoiding trees, large rocks, building foundations, and other obstacles that could damage the cable or require detours to extend the route. Planning cable runs judiciously ensures that underground cabling projects are safe, streamlined, and code-compliant.
Step 3: Determine the Cable Type and Depth
When installing underground cabling, utilize cable types specifically engineered for direct burial applications. Though some believe that outdoor cable can be directly buried underground, outdoor-rated cables may lack the robust structure and water resistance required for subsurface placement and need to be installed in conduit (typically THHN and THWN-2 wire). Standard direct burial cables include USE-2 cable for underground service entrance and UF-B cable for underground feeder, as well as armored cable.
Many people are wondering about how deep to bury a cable. Typically, the depth for burying cables varies depending on the type of conduit used and the type of cable installed. Cables placed in non-metallic conduits, such as the commonly used PVC conduit, are best buried 18 inches (45 cm) or deeper. For directly buried cables with no additional protection, the suggested depth increases to 24 inches (60 cm). If the cable is installed in metallic conduits, a depth of 6 inches (15 cm) usually suffices. As for low-voltage cables with lower safety risks, such as Ethernet or coaxial cables, the typical burial depth is 6 to 12 inches. Compliance with the above depth requirements helps minimize the risk of cables being cut or disturbed during routine excavation activities.
Step 4: Dig the Trench
Dig the trench along the planned line and depth with a shovel or trenching tool. Make sure the trench is wide enough to accommodate the cable and conduits, and measure with a tape measure if necessary to ensure accuracy. Ideally, the bottom of the trench should be soft soil, and if stones or hard gravel are encountered, you can lay a certain thickness of sand or soft soil to cushion and prevent abrasion before laying the cables.
During the excavation process, it’s best to set aside the excavated soil in a designated area, as you will need it later to backfill the trench.
Step 5: Lay and Connect the Cable
Situate the cable within the trench following the predetermined path, exercising care to avoid sharp bends or kinks that could compromise the protective insulation. Then terminate the cable ends at the relevant equipment or junction box and protect the exposed conductors and connectors from moisture and debris buildup with waterproof tape or heat shrink tubing. Once connections are made, leave enough slack in the cable ends for adjustments, termination, and future maintenance.
If installing cable within the conduit, you can apply lubricant to minimize frictional resistance and use clamps as needed to secure the cable to conduits to prevent movement or sagging. Ensure that conduit joints are well sealed and then make the connections.
After laying the cable, it’s a good idea to test it before backfilling the trench to ensure that the cable is working properly.
Step 6: Backfill the Trench
After the cable is laid, it’s time to backfill the trench. First, use a shovel to fill the previously dug soil around the cable as support. As you backfill, periodically tamping down the soil is required to eliminate voids and create a stable foundation. Then place warning tape 6-8 inches above the cables before covering them completely to alert any future excavators to the presence of subsurface utilities. Cease backfilling when the trench is completely filled level with the surface; overfilling can put unnecessary pressure on the cable. In the end, smooth the surface to match the surrounding terrain.
In summary, burying cables is a process that requires careful planning and attention to detail. Following the abovementioned steps, virtually anyone can safely bury underground electrical cables in the garden or yard. However, it is also vital to comply with local regulations and safety codes to ensure the longevity of buried cables and the safety of the surrounding environment.
For expert assistance, consider consulting with a distinguished cable supplier, such as ZW Cable. They possess the expertise to provide you with tailored solutions to accommodate diverse requirements and environments.