Light Distribution Definition

Light Distribution Definition - What does Light Distribution mean?

The prerequisite of best outdoor street lighting is considering the LED distribution types and pattern imposed by Illuminating Engineering Society of North America (IESNA). In many bidding documents of LED replacement for metal halide, halogen, mercury or high-pressure sodium street lamps, the contactors are required to provide the flood lightssatisfying Type I, Type II, Type III, Type IV or Type V light distribution, which is related to IES diagrams.

It is intended for luminaire mounting at or near center of roadways, center islands of parkway, and intersections. It is also meant for large, commercial parking lot lighting as well as areas where sufficient, evenly distributed light is necessary. Type VS is used where the light pattern needs a more defined edge.

Want to know the difference between Type 1, Type 2, Type 3, Type 4 or Type 5 lighting distribution patterns? We show and describe each type and how it could apply to Outdoor Parking Lot Lights.

For instance, Type I & V is symmetrical lighting pattern for narrow sidewalks, crossroad or pavement such kind of longitudinal uniformity street lighting, and tennis courtbasketball court or football field lighting; while Type II, III & IV are asymmetrical outdoor IESNA LED lighting distribution for alley, parking lotwarehouse or building facades. This chapter shares with you what are the LED distribution types and their classification.

lighting distribution types

Iesna outdoor lighting distribution types

Type I Lighting Distribution

Type I distribution is great for lighting walkways, paths and sidewalks, or narrow roads. This type of lighting is designed to be placed near the center of the pathway. This provides good lighting for narrower paths or roadways. If the mounting height is equal to the width of the roadway, then Type I is a good choice.

Type II Lighting Distribution

Type II distribution is used for wider walkways, on-ramps for road ways, as well as other long, narrow lighting. It can accommodate roads wider than Type I. This type is meant for lighting larger areas and usually is located near the roadside. You'll find this type of lighting mostly on smaller side streets or jogging paths. For roadways, the width of the road should not be greater than 1.75X the mounting height.


Type III Lighting Distribution

The type III distribution is meant for general roadway lightingparking areas and other larger areas where an area of lighting is required. Type III lighting needs to be placed to the side of the area, allowing the light to project outward and fill the area. Its throw is taller than Type II but its side to side throw is shorter. For roadways, the width of the road should not be greater than 2.75X the mounting height.


Type IV Lighting Distribution

The type IV distribution produces a semicircular light meant for mounting on the sides of buildings and walls. It's best for illuminating the perimeter of parking areas and businesses. Its projects further out front than Type III but its side to side throw is shorter than Type III. For roadways, the width of the road should not be greater than 3.75X the mounting height.

LED lighting distribution

Type V Lighting Distribution

Type V produces a circular distribution that has the equal light distribution at all positions. This distribution has a circular symmetry of foot candles that is essentially the same at all viewing angles. It is great for parking areas or flooding large areas of light directly in front of the fixture. It is one of the most common distribution types available today.

Since we are LED lighting manufacture, we supply IESNA-compatible, LED explosion proof lightslow cost flood lightsand streetlights that are compatible to type I, II, III, IV & V LED distribution requirement. If you are interested to get the IES files and quotes, please feel free to contact us at email

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