The rule of thumb that can be used to predetermine the length of steel needed when making up a guy is to add the height of the guy attachment above the ground, plus ? of the distance from the pole to the anchor.

• A. 20%
• B. 30%
• C. 40%
• D. 50%

Answer: (D)

When you’re sizing a guy wire, its length is the slanted distance from the anchor on the ground up to the attachment point on the pole, which is the hypotenuse of a right triangle. The two legs are the vertical rise (the height of the attachment above ground) and the horizontal run (the distance from the pole to the anchor). In practice, crews use a simple rule of thumb: add the height to half of the distance to the anchor. This gives a quick, practical estimate that’s reliably long enough to reach the anchor and allow tensioning without requiring exact math in the field. For example, if the attachment is 20 ft high and the anchor is 6 ft away, you’d estimate about 23 ft of wire. The actual length, calculated from the right triangle, would be about 20.9 ft, but the rule provides a workable starting point that balances having enough length with not wasting material. That’s why the 50% rule is the commonly used answer.