Lightide LED LIGHT DISTRIBUTION-1

How to Choose Light Distribution Types I, II, III, IV, V for LED Area & Site Lighting?

Overview

Good visibility under day or night conditions is one of the fundamental requirements. And it can enable motorists to move along roadways in a safe and coordinated manner. Therefore, properly designed and maintained area lighting should produce uniform lighting levels conforming to industry standards.

The prerequisite of the best outdoor area & site lighting is considering the LED distribution types and pattern. And they are imposed by the Illuminating Engineering Society of North America (IESNA).

led-area-&-site-light-solution

Light Distribution Definition

The patterns define how light is dispersed from a fixture. And it is defined by the point at which 50% of the fixture’s luminous intensity is met. Certainly, you will see these distributions used regularly in area lighting, roadway lighting, and parking lot lighting, etc. Therefore, the industry has identified 5 main types of light distribution patterns: Type I, Type II, Type III, Type IV, or Type V light distribution.

Want to know how to choose suitable and correct distribution patterns Type I, Type II, Type III, Type IV, or Type V? We would show and describe each type and how it could apply to outdoor Area & Site Lighting.

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Type I Distribution Pattern

Area Type-I-Distribution Pattern

Type I distribution is great for lighting walkways, paths, and sidewalks. This type of lighting is meant to be placed near the center of the pathway. This provides adequate lighting for smaller pathways.

T1 Light Distribution Shape

Pattern Type I is a two-way lateral distribution having a preferred lateral width of 15 degrees in the cone of maximum candlepower. Therefore, the two principal light concentrations are in opposite directions along a roadway. And this type is generally applicable to a luminaire location near the center of a roadway where the mounting height is approximately equal to the roadway width.

T1 Light Distribution Application

In addition, you can observe the longitudinal and symmetrical lighting for streets. And the bi-directional illuminance is uniformity distributed across the two sides of the light pole. Therefore, we need relatively lower power, ranging from 30W, 40W, 50Wor 60W LED lights to light up this area.

Type II Distribution Pattern

T2 Light Distribution Shape

Type II light distributions have a preferred lateral width of 25 degrees. Therefore, they are generally applicable to luminaires located at or near the side of relatively narrow roadways. And the width of the roadway does not exceed 1.75 times the designed mounting height.

T2 Light Distribution Application

The type II distribution is used for wide walkways, as well as other long, narrow lighting. In addition, 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.

You may choose below Lightide’s led fixtures.

Model# LT-SBAL060/100/150/200/250/320-T2 LED Parking Lot Lights
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Model# LT-SLPB075/150/200/240/300-T2 LED Parking Lot Lights
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Model#  LT-FLXW-100W/150W/200W/320W series 2nd-gen LED Flood Light
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Model# LT-PTB50/80 series   50W/80W Post Top LED Lights
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led area lights Type-II-Distribution
LED parking lot light TYPE-II-PATTERN-DISTRIBUTION-1

Type III Distribution Pattern

led area lights Type-III-distribution.jpg
led parking lot lights TYPE-III-DISTRIBUTION-1.jpg

The type III distribution is meant for general roadway lighting, parking areas, and other areas where a larger area of lighting is required. Therefore, this 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.

T3 Light Distribution Shape

Type III has a preferred lateral width of 40 degrees. This type has a wider illumination area if you make a direct comparison to type II LED distribution. So, it is adapted to light up the highways, parking lot, garage, driveway, as well as sports fields – football pitch, tennis, basketball, volleyball, and more. In addition, it has an asymmetric arrangement as well. The ratio between the width of the illumination area and the height of the pole should be less than 2.75. Since we need to light a large outdoor area, we need to install higher power LED lights for area & site lighting.

T3 Light Distribution Application

Model# LT-SBAL060/100/150/200/250/320-T3  LED Parking Lot Lights
Review
Model# LT-SLPB075/150/200/240/300-T3 LED Parking Lot Lights
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2nd-gen led flood light LT-FLXW-100W/150W/200W/320W series
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Model# LT-FLCD-120W~1500W Rotatable Module LED Flood Lights W/140oX100o  (T3)

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Type IV Distribution Pattern

T4 Light Distribution Shape

The type IV distribution produces a semicircular light meant for mounting on the sides of buildings and walls. And it’s best for illuminating the perimeter of parking areas and businesses. The intensity of the Type IV lighting has the same intensity at angles from 90 degrees to 270 degrees.

Type IV light distributions have a preferred lateral width of 60 degrees. And this distribution is intended for side-of-road mounting and is generally used on wide roadways where the roadway width does not exceed 3.7 times the mounting height.

Power Requirement

In addition, the power requirement for type IV LED pattern is more demanding. We need up to 100 watts, 200 watts, 300 watts, or up to 400 watts LED lights to light up the bridge and façade. Of course, we may choose below Lightide led parking lot light for options.

Model# LT-SBAL100/150/200/250/320-T4 LED Parking Lot Lights
Review
Model# LT-SLPB150/200/240/300-T4 LED Parking Lot Lights
Review

Type-IV-Distribution
TYPE-IV-DISTRIBUTION
Lightide DLC LED Parking Lot Lights

Type V Distribution Pattern

Type-V-Distribution

Type V Distribution Pattern

T5 Light Distribution Shape

Type V produces a circular 360°distribution that has equal light distribution at all positions. And this distribution has a circular symmetry of foot-candles that is essentially the same at all viewing angles.

T5 Light Distribution Application

 In addition, Type V distributions provide the largest, most even pattern of light.  Therefore, it is intended for luminaire mounting at or near the center of roadways, center islands of the parkway, and intersections. Certainly, you may choose below Lightide LED area Lighting fixtures. 

Model# LT-SBAL060/100/150/200/250/320-T5 LED Shoebox Lights
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Model# LT-SLPB075/150/200/240/300-T5  LED Shoebox Lights
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Model#  LT-PTA50  Post Top LED Lights
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Model#  LT-PTR100/150 Post Top LED Lights
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Type VS Distribution Pattern

Type VS produces a square 360° distribution that has the same intensity at all angles. And this distribution has a square symmetry of candlepower that is essentially the same at all lateral angles. Therefore, it is intended for luminaire mounting at or near the center of roadways, center islands of the parkway, and intersections. Moreover, it is also meant for large, commercial parking lot lighting as well as areas where sufficient, evenly distributed light is necessary. So it is used where the light pattern needs a more defined edge.

Type VS light fixtures are Suitable for
  • Large, commercial parking areas,
  • Spaces that need uniformly distributed light.
led parking lot lights TYPE-V-DISTRIBUTION-1

What is the difference between area lights distribution patterns?

Pattern Type Description Ref. Pic.
I
provides a wide, symmetrical light for fixtures located in the middle of a walkway. Area Type-I-Distribution Pattern
 II
 has a slightly wider distribution and is intended for installations where the fixture is placed at the edge of the roadway. led area lights Type-II-Distribution
 III
 casts light about 2.75 times wider than the mounting height of the fixture. led area lights Type-III-distribution.jpg
IV
is known as forwarding throw or asymmetric fixtures. Like Type III fixtures. In addition, 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, with little light falling behind the fixture. Type-IV-Distribution
 V
 are omnidirectional fixtures. They distribute light in a uniform square or circle around the fixture. Type-V-Distribution

IESNA Light Distribution Types

1. Distribution Classification  

A second light distribution classification system is developed by the National Electrical Manufacturers Association (NEMA). This system is used primarily for floodlighting and sports lighting fixtures. It describes the distribution of light within the beam produced by the fixture.

2. NEMA Beam Spread

The “NEMA beam spread” of light refers to the two edges where light intensity spreads horizontal and vertical to 10% of the maximum beam intensity and correlates to whether the light output is very narrow, very wide, or somewhere in between.

Following classifications will help you calculate the horizontal and vertical NEMA rating for your luminary’s particular beam spread, which is also an important aspect in lighting design.

3. NEMA Beam Spread Classifications

Beam Spread (°) NEMA Type Beam Description Beam Projection Distance
10° to 18° 1 Very Narrow 240 ft and greater
 18° to 29° 2 Narrow 200 to 240 ft
 29° to 46° 3 Medium Narrow 175 to 200 ft
 46° to 70° 4 Medium 145 to 175 ft
 70° to 100° 5 Medium Wide 105 to 145 ft
 100° to 130° 6 Wide 80 to 105 ft
 130° and up 7 Very Wide under 80 ft

There you have it. When you decide what are you need lit, make sure you are asking for the correct distribution pattern for your application.