EPA Calculations for Sports Lighting Poles
EPA — effective projected area — is the wind-catching area of everything mounted on a pole, and getting the math right is what keeps poles standing in a windstorm. It's a small calculation with the largest possible consequences, which is why it's done formally rather than estimated.
This reference defines EPA, states the core rule, and explains why every retrofit demands a fresh EPA check.
What EPA is
EPA combines a fixture's projected area with its drag coefficient — roughly, EPA ≈ projected area × Cd. It represents how much wind force the object catches, not just its physical size. Manufacturers publish each fixture's EPA, and poles publish an allowable EPA at a rated wind speed and mounting height. Both numbers are needed to check a design.
The core rule
The rule is simple and absolute:
| Rule | Detail |
|---|---|
| Total mounted EPA ≤ pole's allowable EPA | At the design wind speed and mounting height |
| Sum everything | Every fixture, crossarm, and bracket counts |
| Higher wind speed → lower allowable EPA | A pole fine at 90 mph may be overloaded at 120 mph |
| Higher mounting → lower capacity | The same pole's allowable EPA drops with height |
Both wind speed and mounting height reduce the pole's allowable EPA, so a configuration that passes on one site or at one height can fail on another.
Why retrofits demand a recheck
LED fixtures are usually smaller and lighter than the metal halide they replace, which often helps the EPA case — but "often" is not "always," and you must never assume. Changing the fixture count, adding crossarms, or raising mounting height all change the total EPA. So every retrofit, and every fixture addition, needs a fresh EPA check against the existing pole's rating before proceeding. Duvon runs the EPA check as part of every design and retrofit.
Frequently asked questions
What is EPA?
Effective projected area — the wind-catching area of everything mounted on a pole, combining projected area and drag coefficient (EPA ≈ area × Cd). Manufacturers publish fixture EPA; poles publish allowable EPA.
What is the core EPA rule?
Total mounted EPA (all fixtures, crossarms, brackets) must stay within the pole's allowable EPA at the design wind speed and mounting height.
Why does a retrofit require a fresh EPA check?
LED is usually lighter, which helps, but changing fixture count, adding crossarms, or raising height all change EPA — so every retrofit needs a recheck.
How is fixture EPA found?
Manufacturers publish each fixture's EPA; it's summed with crossarms and brackets and compared to the pole's allowable EPA at the site's wind speed and mounting height.
Does higher wind speed reduce how many fixtures a pole can carry?
Yes — allowable EPA falls as wind speed rises, so a pole carries fewer fixtures in a high-wind region than a low-wind one.
Ask Duvon to run the EPA check for your poles. Get a free assessment at duvonlighting.com/free-quote.