Pole Mounting Height and Lumen Output
Mounting height is the single most important variable in outdoor area lighting design. As mounting height increases, the illuminated area per fixture increases but the footcandle level at ground level decreases for the same lumen output. Footcandles follow the inverse square law: doubling the mounting height reduces footcandles to one-quarter. Higher mounting heights require significantly higher lumen output to maintain target footcandle levels, but allow wider fixture spacing, reducing the total number of poles required.
The footcandle levels in the table above are estimates based on typical commercial LED area light efficacy and standard spacing ratios.
Actual maintained footcandle levels depend on the specific fixture's photometric distribution, pole spacing, reflectance of surrounding surfaces,
and the light loss factor applied for lumen depreciation over time. A Bulbs.com lighting specialist can provide a free photometric layout specifying exact fixture placement,
pole spacing, and maintained footcandle levels for your application. Call Bulbs.com at 888-455-2800 or email customerservice@bulbs.com.
Sensors & Controls
When the LED area lights are paired with photocells, motion sensors, and networked lighting controls, they deliver maximum energy savings and qualify for the highest utility rebate tiers in most commercial and municipal programs.
Bulbs.com representatives can verify rebate eligibility in your utility territory and assist with control system specification. Call Bulbs.com at 888-455-2800 or email customerservice@bulbs.com.
Mountings
LED area lights support multiple mounting configurations to accommodate different pole types, structural conditions, and installation requirements. Selecting the correct mounting type is essential for both fixture performance and code compliance.
The mounting configuration affects beam aim, EPA (effective projected area) wind load calculations, and the ability to adjust the fixture after installation.
| Mounting Type |
Typical Applications |
Key Considerations |
| Slip Fitter (Tenon)
Slides over a 2 3/8" or 2" OD tenon on top of a round pole. Most common outdoor pole-mount configuration |
Parking lots, roadways, campuses, shopping centers, sports fields |
Verify tenon OD and fitter ID match. Adjustable slip fitters allow ±5 or ±15 tilt for aiming |
| Trunnion/Yoke
U-bracket mounts the fixture between two arms. Can be wall-mounted, surface-mounted, or mounted to a mast arm via an adapter. |
Building walls, canopies, bridge undersides, sports lighting mast arms |
Most versatile mounting option as it can fit on many different mounting surfaces without adapters. |
| Knuckle/Adjustable Arm
Articulating knuckle allows the fixture to be aimed in multiple axes after installation. Mounts to poles, walls, or surface structures. |
Security lighting, facade illumination, flag poles, accent applications requiring precise aiming. |
Greater aiming flexibility than fixed slip fitter. Useful when optimal beam angle cannot be predetermined. |
| Direct Arm/Mast Arm
Fixture mounts directly to a horizontal mast arm projecting from a pole. Common in roadway and street lighting configurations |
Roadways, parking lot perimeters, pathways, municipal street lighting |
Most common option for parking lot illumination when the light is pointing down towards the surface. |
| Surface/Wall Mount
Fixture mounts flush to a vertical wall or building surface using an integral back plate or mount bracket. |
Building perimeters, loading docks, stairwells, entry points, pathways |
Wall mounting reduces mounting height vs. pole.Factor reduced height into photometric calculations. |
Beam Distribution
LED area light distribution types are classified by the IESNA (Illuminating Engineering Society of North America) photometric standards,
which define how light is distributed laterally and longitudinally relative to the fixture mounting position.
Selecting the correct distribution type for your application and pole placement is as important as selecting the correct lumen output.
Having an incorrectly specified distribution type will result in poor uniformity, wasted light outside the target area, and unnecessary light trespass onto adjacent properties.
Type III — The Standard for Commercial Parking Lots
Type III distribution is the most widely specified distribution type for commercial parking lot lighting. It delivers a medium-to-wide lateral spread with significant forward throw.
The light pattern extends approximately 2.75 times the mounting height in front of the pole, making it ideal for situations where the pole is placed at the edge or perimeter of the parking area.
For a 20 ft mounting height, a Type III fixture illuminates approximately 55 feet in front of the pole.
Type III is specified when poles are placed along the edge of a parking lot, driveway, or roadway with the lit area extending away from the pole in one primary direction.
Type IV — Wide Throw for Large Perimeter Applications
Type IV distribution delivers a wider forward throw than Type III. It is typically designed for higher mounting heights then the Type III as Type IV provides a strong lateral spread and minimal backlight.
Type IV is specified for large parking lots, big-box retail properties, and roadway perimeter applications where fixtures are mounted at the boundary of the lit area and light needs to reach deep into the space.
The minimal backlight characteristic of Type IV also makes it the preferred distribution type for applications where light trespass onto adjacent properties or roadways must be controlled,
such as parking lots adjacent to residential neighborhoods.
Type V — Symmetric for Lot Interiors
Type V distribution delivers equal illumination in all lateral directions (360°) from the fixture, making it the correct specification for pole placements in the interior of a parking lot where light needs to be distributed uniformly in all directions.
Type V fixtures are specified when the pole is centered within the area being lit such as an interior island pole in a large parking lot rather than at the perimeter.
Type V Square is a variant that distributes light in a square pattern optimized for grid-pattern pole layouts, maximizing covered area and uniformity between poles in a regular grid.
Full Cutoff and Dark Sky Compliance
Full cutoff (FCO) optics restrict light output above 90°, eliminating uplight and reducing sky glow. Full cutoff area lights are required by many municipalities and dark sky ordinances,
and are a prerequisite for IDA (International Dark-Sky Association) Dark Sky Place certification. Backlight-Uplight-Glare (BUG) ratings quantify the amount of backlight (B), uplight (U), and glare (G) produced
by a fixture at its installed aim angle. Many utility rebate programs and municipal specifications require fixtures to meet specific BUG rating limits.
A lower number indicates less light in that zone. Consult local dark sky requirements and utility specifications before finalizing distribution type selection.