Product information

• Dredging Foundation - Data sheet
• Dredging Foundation - Installer manual. 
  The text is in Norwegian, but the illustrations are clear and can be used as a visual reference.

How to install the dredging foundation

The prefabricated foundation is compatible with the following Zaptec columns: Zaptec Column, OnePole, Premium (one, two and four outlet versions).

The following steps are based on recommendations from the supplier. Always consult your local supplier or Zaptec representative for specific guidance and to ensure compliance with local regulations.

Installation steps

1. Place the foundation on a well-compacted layer of 30/60 gravel.
2. Add 8/16 gravel inside the foundation, up to the level of the cable entry.
3. Fill around the outside of the foundation with 30/60 gravel, up to just below the cable entry. Level and compact carefully.
4. Insert the cable conduit, ensuring it ends well above the foundation to prevent sand and gravel from entering.
5. Add 8/16 gravel outside the foundation to cover the conduit (about 30cm). 
6. Continue filling outside with 30/60 gravel, up to ground level and just below the foundation bolts. Compact every 30 cm.
7. Fill the inside of the foundation with 8/16 gravel. This prevents ground heat from circulating inside the column. 
8. After installing the column, fill the hole up to finished ground level with 8/16 gravel. 

Note on ground frost and installation depth

If you are installing the foundation anywhere with cold winters, pay close attention to ground frost. Frost can shift the foundation if it is not installed deep enough.

For example, in Sweden, there are three main frost zones:

• Zone 1 (South): Recommended depth - 500 mm.
• Zone 2 (Central): Recommended depth- 700 mm.
• Zone 3 (North): Recommended depth- 900 mm.
• Zone 4: Recommended depth - over 1,000mm (rarely needed for most projects).

The foundation itself can still be 500 mm, but in colder zones, you need to dig a deeper hole and fill it with extra gravel. This prevents frost from moving the foundation over time.

Updated 13 November 2025 11:16