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Calculating Effective Projected Area (EPA)

Calculating Effective Projected Area (EPA)

Calculating Effective Projected Area (EPA)


To calculate the Effective Projected Area (EPA) for situations like outdoor lighting (involving fixtures and poles) it's a function of both the projected area AND the drag coefficient. Check out this literature from GE:


Click on "Poles/Brackets," and on the 3rd page of the pdf it says what I said.

One little difference between using the drag coefficient or not is that the orientation of the pole might differ in calculating the EPA. For example, if you look at a square pole, it has a higher projected area if you look at it like a diamond and say PA = height x width x 1.414. But a diamond has lower wind resistance than a square, so the maximum EPA might come from other orientation where you have PA = height x width.

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