What Is Effective Projected Area (EPA) of Flood Light?

Outdoor lighting normally utilizes LED flood lights and these fixtures are mounted on high poles. There are many posts about proper outdoor lighting fixtures selection, but few posts explain the importance of poles to support these outdoor flood lights. Outdoor environments such as the heavy wind are risky for safety and security. Proper support of flood lights is relevant to structural aspect, and it requires careful analysis. It is helpful to understand some of terminologies, such as Effective Projected Areas. Today, let’s talk about this technical topic - EPA (Effective Projected Area).

Understanding EPA

EPA (Effective Projected Area) refers to the total surface area of items such as the lighting fixtures that the pole can support at a given wind velocity. For flood lights, EPA is a way to measure the strength of a light pole. As known, the wind can touch almost anything. So engineers or LED lighting manufacturers use the EPA to determine the force that the wind is going to apply to the structure. This value is used in combination with a luminaire’s net weight to determine the mounting requirements to help to choose the right pole, mounting heights, mounting ways, etc. 

EPA is the measurement of a three dimensional light fixture on a two dimensional area (see the below drawing). 

How to calculate Effective Projected Area (EPA) ?

Equation: To determine the EPA of a luminaire, the frontal projected area is multiplied by

the drag coefficient of the luminaire.

EPA = (Frontal Projected Area) x (Drag Coefficient)

Take our SP01 LED flood light as an example:

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