Installation Guide

SOUTHWEST WINDPOWER DOCUMENT 0228 REV A
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Holes for concrete anchors should be at least 2 feet in diameter and at least 3 feet deep. The
attachment should be placed in the hole and concrete or cement poured around it to a depth of at
least 1 foot. Once the concrete has set 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 can be drilled and a large eye-bolt cemented into it. For very
hard rock such as granite and basalt, a ¼ inch diameter bolt 1 ½-inch deep can be used. For slightly
softer rock such as dacite, welded tufts and some denser varieties of sandstone, a 3/8-inch diameter or
larger bolt at least 3 to 4 inches deep can be used.
For softer types of rock, such as sandstone or limestone, a hole 1 inch diameter and 8 inches deep can
be drilled and an eye-bolt 5/8 inch in diameter cemented into it. If cement is to be used, it should be
mixed just thin enough to pour and poured into the hole before the bolt is installed. This will help to
insure that the cement goes to the bottom of the hole and help prevent bubbles that may compromise
the strength of the attachment. If expansion bolts are to be used, follow the instructions supplied with
the bolts. There are several different types of expansion bolts that are installed using different
methods.