## Surveying point on a power line pole

## Surveying point on a power line pole

(OP)

I am a structural engineer in Canada and for the record my survey skill are limited so please excuse my terminology and knowledge.

We have just won a job where we need to measure the height differences on an electrical pole. At the top there are high voltage power lines, and around mid height on the poles there are mobile phone lines. We need to find out if the space between the upper power lines and the mobile phone lines is sufficient to run another power line.

I have used EDMs many moons ago and at first thought we could use one to determine the heights. We cannot do that though because we risk our guy with the prism getting fried on the pole! I am wondering what other options do we have? Perhaps measure the horizontal distance to the bottom of the pole and then sight the points on the pole that we need to measure and get their heights based on the vertical angles?

I would be very thankful for your help.

Thank you,

Naggud

We have just won a job where we need to measure the height differences on an electrical pole. At the top there are high voltage power lines, and around mid height on the poles there are mobile phone lines. We need to find out if the space between the upper power lines and the mobile phone lines is sufficient to run another power line.

I have used EDMs many moons ago and at first thought we could use one to determine the heights. We cannot do that though because we risk our guy with the prism getting fried on the pole! I am wondering what other options do we have? Perhaps measure the horizontal distance to the bottom of the pole and then sight the points on the pole that we need to measure and get their heights based on the vertical angles?

I would be very thankful for your help.

Thank you,

Naggud

## RE: Surveying point on a power line pole

I suggest you review your trigonometry. Assuming your poles are indeed vertical, a measurement to the base and the two points in question are sufficient to determine the height difference.

TTFN

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## RE: Surveying point on a power line pole

B+W Engineering and Design

Los Angeles Civil Engineer and Structural Engineer

http://bwengr.com | http://bwstructuralengineer.com | http://bwcivilengineer.com

## RE: Surveying point on a power line pole

Several years ago, I had to find the height of a roughly 80-foot-tall high-mast light pole for which no record information existed, so I used its shadow. The pole needed to be moved, and the height was one of the pieces of data I needed for designing the new foundation and anchorage. In addition, from the width of the far end of the shadow, I determined the diameter of the top of the tapered pole so I could estimate weight and wind capture. I also used the shadow cast by the lighting array to estimate it's size for the wind load calc and to find a comparable lighting array to estimate its weight. Here is how I described the procedure in my Mathcad document of the calculation:

In my case, I used this equation: Hp = ((Ls + Rf) * TAN(A)) - Hf

Hp = estimated height of pole

Ls = length of shadow from the face of the existing foundation

Rf = radius of the existing foundation

A = altitude angle of the Sun

Hf = height of the existing foundation above the parking lot

BTW, my two results were 83.0 feet and 83.7 feet, so I used 84 feet.

==========

"Is it the only lesson of history that mankind is unteachable?"

--Winston S. Churchill

## RE: Surveying point on a power line pole

distance*(arcsin(top)-arcsin(middle))

TTFN

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## RE: Surveying point on a power line pole

Or if a cloudy day and you can see a laser beam, use my Hilti measuring device and shoot upwards from the base of the pole to the cable...

Dik

## RE: Surveying point on a power line pole

Thanks to all of you for your replies, I appreciate you taking the time to help.

Regards.

## RE: Surveying point on a power line pole