Friday, April 27, 2012

High-Tension Wire Fall Zones

Every residential appraiser should have this in their trick bag.  You’re appraising a house that backs to high-tension wires.  FHA requires that the home is outside of “Fall Zone”.  You have no ideal how tall the towers are.

On way to estimate the fall zone is an indirect measurement of height based on some simple algebra.

First, start by standing a sufficient distance from the tower so you can line up the height within the length of a ruler as you look at the tower past the ruler with an out-stretched arm. Take note of the height of the tower as you eyeball the tower. It helps to close one eye.  For this example we will use 10 inches (A). Then measure the distance from your eye to your thumb. In my case, that distance is 28 inches (B). Measure the distance to the tower which we will call Y.  We will use 140 feet for this distance.  

Solve for X using the following equation.   

              A                     X
            ------       =      -----
              B                     Y

 10                     X
-----      =         ------
 28                   140

Cross Multiply…

             28X     =          (10) (140)
Divide each side by 28....

            28X               1400
            ------     =      -------
28                            28

Solve for X....  

  X       =          50

The tower is approximately 50 feet tall.  Within a reasonable margin of error, you can conclude whether or not the house is within the fall zone.  If the house is a sufficient distance beyond 50 feet from the base of the tower, it would be safe to say the house is outside the fall zone.  


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