WHISPER 100/WHISPER 200 24 Foot Tower Manual
Document #0026 REV E
SOUTHWEST WINDPOWER
5/20/05
11
Holes for concrete anchors should be at least 24 in. (60 cm) in diameter and at least 36 in. deep.
The attachment should be placed in the hole and concrete or cement poured around it to a depth of
at least 12 in. (30 cm). Once the concrete has cured (see instructions on supplied with your
concrete for curing times) it should be buried before use.
Anchoring in Rock:
If your tower site has large rocks around it or is located on solid rock,
expansion bolts in the rock may be the best means of anchoring your guy wires and base tube. A
hole is drilled into the rock and the bolt is placed in the hole with an attachment hanger, a piece of
chain or other loop to connect to the guy wires.
For expansion bolts to work properly the rock must be of good quality and not fracture easily. If the
rock quality is poor a larger deeper hole must be drilled and a large eye-bolt cemented into it. For very
hard rock such as granite and basalt, a ¼ inch (6 mm) diameter bolt 1 ½ inch (4 cm) deep can be used.
For slightly softer rock such as dacite, welded tufts and some denser varieties of sandstone, a 3/8-inch
(10 mm) diameter bolt 3 to 4 inches (7-10 cm) deep should be used.
