What are lighting distribution patterns? Lighting distribution is basically the projected pattern of light that a fixture will disperse onto a surface.
The patterns define how light is dispersed from a fixture and are defined by the point at which 50% of the fixture’s luminous intensity is met. You will see these distributions used regularly in parking lot lights, area lighting, floodlighting & roadway lighting. While there are other symmetrical and asymmetrical lighting distribution types, the industry has identified 5 main types of lighting distribution patterns:
Type I light distribution provides a wide, symmetrical light for fixtures located in the middle of a walkway. The width of the pattern it creates is about equal to the fixture’s height.
Type I fixtures are good for:
- Narrow walkways
- Border lighting
Type II fixtures have a slightly wider lighting distribution patterns and are intended for installations where the fixture is placed at the edge of the roadway.
They light an area up to 1.5 times wider than the mounting height of the fixture. For example, if the fixture is 10 feet high, it will cast light up to 15 feet wide on the area below.
Type II fixtures are best suited for:
- Wide paths
- Side streets
Type III light distribution casts light about 2.75 times wider than the mounting height of the fixture.
Fixtures should be placed along the side of the area to be lit, allowing the light to project outward. A fixture with Type III distribution mounted to a 10-feet pole will cast light about 27.5 feet in width from the light source.
Type III fixtures are ideal for:
- General parking areas
Type IV light distribution fixtures are known as forwarding throw or asymmetric fixtures.
Like Type III fixtures, these light fixtures will cast light 2.75 times wider than their height, but produce a more rounded distribution pattern that pushes the light outward, will little light falling behind the fixture. They’re best mounted on walls or used to illuminate specific areas.
Type IV fixtures work best on:
- Building exteriors
- Perimeter of parking areas
Large spaces usually require Type V light fixtures. These fixtures distribute light evenly around all sides of the fixture, usually in a square or circular pattern.
Type V light fixtures do best on:
- Large, commercial parking areas
- Spaces that need uniformly distributed light
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