How to seal the top of the distribution box

Seal the top of a distribution box by using a secure lid with twist-lock or gasket seals, optionally reinforced with sealant and screws for a watertight and tamper-resistant installation.

Step-by-Step Instructions

1. Prepare the Box and Lid Ensure the distribution box is properly installed and leveled in the trench. The top of the box should be clean and free of debris. If using a riser, attach it securely to the box with stainless steel screws to allow at-grade access for inspection and maintenance . 2. Select the Proper Seal Choose a non-corrosive, low-density polyethylene seal or gasket compatible with your box and pipe size. For standard 4” or 6” pipes, twist-lock seals or Polylok seals are commonly used . Ensure the seal matches the inlet/outlet configuration. 3. Apply Sealant (Optional for Increased Head or Smooth Pipes) For smooth-walled pipes or installations with higher water head, apply a bead of asphalt-based or compatible sealant where the seal lip contacts the box. This enhances watertightness . 4. Insert and Lock the Seal Place the seal into the box opening, then twist and lock it at the designated locking points. Polylok seals may require pushing the seal from inside the box and securing it with a nut from the outside. Ensure the seal is oriented correctly, especially for smaller pipe sizes . 5. Insert the Pipe Push the pipe at least one inch into the box through the seal. For corrugated pipes, compress the first few corrugations, insert the pipe, then allow it to expand to its original shape to ensure a tight fit . 6. Secure the Lid Place the lid on the box. For added safety and tamper resistance, fasten the lid with stainless steel screws if the box design allows. This prevents accidental removal and maintains a sealed environment . 7. Backfill Carefully Hand backfill around the box in layers, tamping each layer starting 8” away from the box to avoid deflection. Ensure the lid remains in place and the top is flush with grade .

Tips for Long-Term Performance

• Regularly inspect the lid and seals for damage or wear.
• Use UV-resistant materials if the box is exposed to sunlight.
• Ensure all pipe connections remain tight to prevent leaks or infiltration. By following these steps, the distribution box will remain watertight, secure, and compliant with local codes, ensuring proper function and longevity of the system .