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NRG_34m_TallTower_Installation_Manual_and_Specifications_Rev_1.05.docx
19 April 2011
Installing Screw-In Anchors
Note: Unlike a tent stake, screw-in anchors are installed in line with the pull of the guy wires from the tower. It is
important to install the anchor at an angle, so the eye of the anchor is toward the tower and the helix screws in away
from the tower. If the anchor is incorrectly installed straight into the ground, the load will bend the rod and pull it
through the ground, allowing the guys to go slack. Refer to the appropriate stamped drawing in the Appendix to
determine the angle of the tower guys from the ground.
Figure 9: Installing Screw-in Anchors
Screw the anchor into the ground by placing a stout bar through the eye of the anchor, and rotating clockwise. It is
sometimes helpful to start the anchor into the ground straight down for the first turn, then push it down to the correct
angle and complete the installation. Continue screwing the anchor into the ground until about 150 mm (6 inches) of
the anchor rod remains above the ground.
If the anchor cannot be installed due to rocks in the soil, or other obstacles, try placing the anchor as much as 1 m (3
feet) from its ideal position to avoid the obstacle, or replace the screw-in anchor with the correct anchor for the soil.
Arrowhead anchors are often suitable for rocky soils.
If necessary, a hole can be dug for the screw-in anchor to the proper installed depth, the anchor placed in the hole,
and the hole back-filled. The earth must be tamped onto the anchor hard while back filling. The holding power of an
anchor placed this way will not be as great as an anchor screwed into undisturbed soil. If in doubt, get professional
advice on whether this option will work for your site.
Installing Arrowhead Anchors
Arrowhead anchors are designed for all soils but are especially effective in rocky soils. The arrowhead anchor is
driven into the soil with a drive rod. The rod is removed and the anchor is left in the ground. Then the anchor must
be pre-tensioned which will cause the anchor to rotate in the ground and develop its full holding potential.
Like screw-in anchors, the arrowhead anchor must be placed so the force from the guy wires pulls directly on the
anchor. Drive the arrowhead anchor away from the tower at an angle into the ground. Refer to the appropriate
stamped drawing in the Appendix to determine the angle of the tower guys from the ground.
Note: It is important to drive the anchor at an angle. If the anchor is incorrectly installed straight into the ground, the
load will result in the anchor cable cutting through the ground until the angle is correct, resulting in significant slack in
the tower guys, and possible tower failure.