Can anyone tell me how to estimate a pole's height from the ground? I am curious, I have seen this done in the past but have forgotten the technique the foreman used.
Can anyone tell me how to estimate a pole's height from the ground? I am curious, I have seen this done in the past but have forgotten the technique the foreman used.
Depends on how accurate you need to be:
You can place a stick of known height next to the pole and estimate how many multiples of this stick make up the pole height.
or
Stand back and visually pick the 1/2 way point of the pole top to ground. Then pick the 1/2 way point of this point to ground. Continue until you reach a point that you can measure. then multiply back to get the height.
or
Use an inclinometer that will allow you to measure the a % difference from the ground line to the top. This % difference is the % of your horizontal distance from the pole
or
From a known horizontal distance, sight a straight line from your location on the ground, to the top of a reference stick or person's head between you and the pole, to the top of the pole. The pole height is:
height = distance from you to pole * (height of reference / your distance to reference)
add: you could also ratio the shadow length of a stick of known height to the shadow length of the pole, if the sun is cooperating.
Last edited by mivey; 03-31-09 at 01:08 PM.
Read the brand. Normally, it is about eye level and will have something like 5-35 or 3-40 or similar. the first number is the class (how fat it is) and the second is the height. The pole is normally set 10% + 2' deep. Therefore, if the brand says 1-55, it is about 7½ feet deep and about 47½ feet above grade. :smile:
Charlie Eldridge, Indianapolis, Utility Power GuyResponses based on the 2011 NEC, unless stated otherwise.
Angles, 10 feet from base find your angle to the top. Example, a 20ft pole should be at 60 degree, a 40ft should be at 75 degree.
Get a 45 degree drafting square for a couple $'s. With the square held level, sight down the length of the 45 degree side and walk away from the pole until the tip of the pole is lined up with the square. Measure the distance from the pole to your feet and add your own height to this.
Another method is to use the length of the shadow and sun data. This only works if the shadow is on level ground (or measured at level point from base), and of course, on a sunny day
Sun data can be obtained here: http://www.usno.navy.mil/USNO/astron...ices/alt-az-us
H = height, SL = shadow length, AA = altitude angle
Last edited by Smart $; 03-31-09 at 02:38 PM.
We teach our First Class Boy Scouts to visually lay the pole or tree down. Stand back a ways and hold a stick up at arms length. Move the stick until your thumb covers the bottom of the pole and you sight the top of the pole with the top of the stick. Roll your hand 90 degrees and note where the stick top is aiming and measure the distance from that point back to the pole. It is rough but will get close.
My uncle the logger would walk until he could see the tree top when bending over and looking between his legs. His stomach was smaller than mine and that position gave him a 45 degree viewing angle. He would drive a stake and drop the tree top within 5 feet of the stake. It could be he was just fooling me with his bend over antics.
Bob Wilson
Hold a 10' stick of conduit straight up. Measure the shadow. Measure the poles shadow.
Multiply the length of the Poles shadow by 10. Then divide by the length of the conduits shadow.
Pole Shadow x Conduit Length / Conduit shadow
That'll get ya pretty darn close, and all you need is your tape, and some conduit. I would assume these are handy? :cool:
Otherwise measure your shadow...
My 2¢
Doug S.
Get a protractor or a carpenter's level.
With a carpenter's level you will need to go out to a distance where the level, set on the ground, (or close enough to it), will point to the top of the pole with the 45 deg bubble indicating level. The pole height equals your distance from the base of it. OR
Take a protractor and walk any distance from the pole, get an angle that you are looking up to the top of the pole, (the same angle that Smart $ shows to the sun in the previous post), use the same formula-the Height = distance from the pole x the Tangent of the angle.
Just for kicks, do both, see how close you get.
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