Lighting distribution types: Useful and updated knowledge for you

There are many important factors to consider when choosing a suitable lamp. Lumens per watt, lamp type, warranty, and color temperature are all necessary, but what about light distribution? 

One of the most important things to consider is the lighting distribution types of the fixtures. If you know how to correctly calculate the layout with the right institutions and proper light distribution, you can reduce the number of fixtures and get a better design. You can have great fixtures, but it’s as good as the layout if you don’t put the light where you want it to be! 

What is lighting distribution? 

The model defines how the lamp scatters light. And it is determined by the point where it reaches 50% of the brightness of the lamp. Indeed, these distributions are frequently used in lighting areas, streets, parking lots, etc. As a result, the industry has identified five main patterns of light distribution: Type I, Type II, Type III, Type IV, or Type V light distribution. Want to know how to choose the suitable distribution model for Type I, Type II, Type III, Type IV, or Type V? We’ll tell you what each is and how you can apply it to outdoor spaces and site lighting.

What are lighting distribution types? 

There are two classification systems of lighting distribution: by IESNA and by NEMA. Let’s find out what they are.


The best prerequisite for outdoor space and site lighting is to consider LED types and distribution models. And they are adopted by the Illuminating Engineering Association of North America (IESNA).

The system of IESNA has five categories. 

Classification systems of lighting distribution by IESNA
Classification systems of lighting distribution by IESNA

Type I

The Type I distribution is ideal for driving driveways, paths, and sidewalks. This type of light is designed to be located near the center of the lane. It provides proper lighting for miniature bearings. 

Type I is a bidirectional lateral distribution with a preferred lateral width of 15 degrees at the peak power cone of a candle. Therefore, the two primary sources of light face each other on the path. Also, this type is typically applied to luminaire locations near the center of the aisle. It is where the installation height is approximately equal to the width of the gallery. 

In addition, you can observe vertical and symmetrical linear light. And the bidirectional lighting is evenly distributed on both sides of the floor lamp. Therefore, low power is required to illuminate this area, starting with a 30W, 40W, 50W, or 60W LED.

Type II

The Class II light distribution has a good side width of 25 degrees. Therefore, they are often applied to luminaires on or near the side of relatively narrow roads. Also, the width of the course does not exceed 1.75 times the planned installation height.

Type II light distribution is used for wide corridors and other long and narrow lights. This type is also intended to illuminate a larger area and is usually near the roadside. This lighting system is mainly found in small streets and jogging tracks. 

Type III

Class III distributions are intended for general lighting of streets, car parks, and other areas requiring more lighting. Therefore, you should place this lamp on the side of the site. It allows light to illuminate the exterior and fill the room.  

The recommended edge width for Type III is 40 degrees. This type has a large illuminated area when compared directly with the distribution of Class II LEDs. Therefore, it is suitable for lighting highways, parking lots, garages, driveways, and sports grounds. In addition, it has an asymmetrical layout. The ratio of the width of the illuminated area to the height of the columns should be less than 2.75. Since you need to illuminate a large outdoor room, you need to install higher wattage LEDs to illuminate the area and the site.

Type IV

Class IV distributions produce semi-circular lights for mounting on the sides of buildings and walls. It is also ideal for illuminating the surroundings of parking lots and commercial activities. Class IV light intensity has the same passion at angles from 90 degrees to 270 degrees. The Class IV light distribution has a good side width of 60 degrees. The distribution is also designed for side mounting and is typically used on wide roads where the width of the platform is 3.7 times the mounting height or less. 

In addition, the power requirements for Class IV LEDs are becoming more stringent. Lighting on terraces and façades requires LED lamps up to 100 watts, 200 watts, 300 watts, or 400 watts. Of course, you can optionally place it under the optional LED parking light.

Type V

Type V produces a 360° circular distribution with the same light distribution in all positions. And this distribution has circular symmetry of the base of the ladder, which is essentially the same at all viewing angles. 

In addition, the V-pattern distribution provides the most prominent and most coherent light pattern. Therefore, it is intended to install lights in the middle of roads and intersections. Of course, you can choose from the following types of LED area lights.

Moreover, type V also has its upgraded version- the Type VS. This distribution has a square symmetry of candle energy that is essentially the same in all angles. It is also suitable for well-lit commercial parking lots and areas where well-distributed light is required. Therefore, it is used when light modeling requires lighter edges.

#2. NEMA

The second light distribution classification system was developed by the American Electrical Manufacturers’ Association (NEMA). This system is mainly used for headlights and sports lights. It represents the distribution of light within the beam produced by the tissue.

“NEMA beam spread” of light refers to horizontal and vertical spreads where the light intensity is equal to 10% of the maximum beam intensity. It correlates with very narrow, very wide, or central light outputs. The following classifications help calculate the horizontal and vertical NEMA ratings for a particular beam spread of the fixture, which is also an essential aspect of lighting design.

NEMA: Lighting distribution types
NEMA: Lighting distribution types

To determine the NEMA classification of the luminaire for the asymmetrical beam, complete the following formula: 

Asymmetrical beam = XºH (horizontal aperture) x XºV (vertical extension) 

Based on seven beam types, when using luminaires Considering the NEMA type 6 x 5 specification, the horizontal beam width is 100° 130° and the longitudinal width is 70° 100°, classified as the large-area flood.

The Impact of Mounting Height on Illumination

#1. Freeing up space in the room 

One of the most critical advantages of mounting height is to save space. Especially for small condominiums, you can take advantage of the dedicated space to maximize or tidy up room space. 

***Refer to more: Best Floor Lamps For High Ceilings – Lighting the whole house space

#2. Most reasonable display height 

The illumination in many people’s homes is low, and the sofas are relatively large. If the light is placed directly in the TV cabinet, the viewing angle is a top-to-bottom view. Such heights make it uncomfortable to improve your eyesight. 

When choosing a light stand, you are free to choose the height. Usually, the light is about 1.3 meters from the floor. However, you should analyze some dimensions based on the size of the sofa and try to keep the sofa flat or slightly below the view. It can neither be too low nor too high. If it is too high, your neck will hurt. And if you place the light bulb directly in front of your eyesight, these potential dangers are still present.

What is the light distribution angle?

The beam angle of a lamp is the angle at which light is distributed or emitted. Lamps like halogen (and some LEDs) come in various degrees from 30 degrees to 60 degrees, with some oversized halogen lights up to 120 degrees. These are typical acronyms for beam angle propagation.

How many types of indoor lighting?

Three types: Ambient lighting, Task lighting and Accent Lighting

#1. Ambient lighting

General or ambient lighting is intended to illuminate the entire room. The light provides a uniform level of illumination throughout the space, independent of other light sources. In addition, its objective is to ensure easy and safe circulation and to create an overview of the room. Ambient light hits the wall and bounces, illuminating as much space as possible.

#2. Task lighting

Work lights illuminate a person’s activities in a particular space, such as reading, cooking, or working on a computer. This type of work requires bright lighting in a small focal point of the room. For more comfortable lighting, avoid bright or distracting lights. It is also convenient to install a single switch for focal lighting, separate from the general light switch in the room.

#3. Accent Lighting

Spotlights are primarily used to focus on a particular point of interest or to achieve the desired effect. This type of lighting gives the impression of a larger room. It is most often used to emphasize a collection of architectural elements, exterior designs, sculptures, or objects. As a general rule, proper accent lighting requires at least three times the focal light typically provided by ambient light.


Above are the concept and lighting distribution types that we want to share with you. Hope the above information will be useful to you. Follow the next articles here to update more useful information!