What Are Light Distribution Types I, II, III, IV, V?

Are you dealing with poor lighting in your spaces? Inadequate light distribution can create zones that are either too dim or excessively bright. Understanding the different types of light distribution is key to finding the perfect lighting solution for your needs.

Selecting the appropriate light distribution is essential for achieving optimal lighting. This article will guide you through the various light distribution types and their applications, enabling you to make informed decisions for your lighting requirements.

The Illuminating Engineering Society of North America (IESNA) classifies light distribution to optimize outdoor lighting designs for roads, walkways, and parking lots. This classification ensures efficient and effective light spread. Type I distribution targets narrow paths, improving visibility and safety. Type II covers broader areas like entrance roadways without excessive spillage. Type III suits large areas such as parking lots, offering uniform lighting with minimal glare. Type IV, with a semicircular spread, is ideal for the outer edges of properties, enhancing safety and security. Type V provides circular light distribution, ensuring even coverage in central, open areas.

Keep reading as we explore each light distribution type and their best use cases.

Type I

Type I light distribution is tailored for pathways and narrow spaces where directed lighting is essential. It features a bidirectional lateral spread, commonly employed to illuminate walkways, sidewalks, and minor roads. The primary beam spans approximately 15 degrees, casting light forwards and backwards along the intended path. This distribution is ideal for focusing light on specific sections of a path to enhance visibility and safety. The main advantage of Type I is its precise lighting placement, ensuring no light is wasted and the path is both well-lit and safe for nighttime use.

Type II

Type II light distribution is designed for broader walkways, entrance roads, and similar elongated spaces, with a lateral spread of about 25 degrees. This setup is optimal when the area’s width does not exceed 1.75 times the height of the light fixture. It’s used to illuminate lesser streets, wider sidewalks, and jogging paths, focusing light downwards and to the sides to cover the area thoroughly without unnecessary spillage. This distribution type ensures the area is well-lit, enhancing visibility for both pedestrians and drivers.

Type III

Type III light distribution suits larger areas such as roadways and parking lots, offering a medium-wide lateral spread of 40 degrees. It’s typically mounted on the perimeter of the areas to be lit, tailored for spaces where the breadth does not surpass 2.75 times the height of the lighting pole. Type III distribution casts light outward and sideways, providing uniform illumination over large spaces without glare or light pollution. This is particularly effective for extensive areas needing broad visibility and safety.

Type IV

Type IV light distribution is utilized for illuminating the peripheries of large spaces like parking lots and business complexes, featuring a semicircular spread of 60 degrees. It is mounted on building sides or the outer edges of open areas, casting a broad swath of light across a large zone. This lighting type is crucial for the safety and security of property edges, aiding in crime and accident prevention. It’s ideal for areas where the width is up to 3.7 times the height of the light pole.

Type V

Type V light distribution, distinct in its circular form, is used centrally in large, open spaces such as intersections, central park islands, or vast parking lots. This distribution ensures light spreads evenly in all directions, regardless of the viewing angle, providing comprehensive coverage. It’s especially beneficial for lighting large areas uniformly, ensuring every section is equally illuminated for safety and visibility.

IESNA Light Distribution Types

What are the main differences between IESNA and NEMA lighting distribution types?

The main differences between IESNA and NEMA lighting distribution types are how they classify them and the typical applications for each type.

IESNA Light Distribution Types

IESNA categorizes light distribution patterns to assist in determining the coverage of light across a horizontal plane. This system is crucial for planning outdoor lighting installations such as roadways, parking lots, and pedestrian areas. The classifications start with Type I, targeting narrow paths with directional lighting from a central source, and extend to Type V, which evenly spreads light in a circular pattern, ideal for illuminating large, open spaces.

NEMA Beam Spread Types

In contrast, NEMA defines light distribution through beam spread, considering both vertical and horizontal angles where light intensity reduces to 10% of its maximum. This approach is vital for specifying the focus of floodlights and spotlights, with classifications ranging from Type 1, producing very narrow beams perfect for highlighting distant targets, to Type 7, creating a broad beam that is effective for wide, close-range illumination.

In summary, IESNA distribution types are designed for general and broad outdoor area lighting, focusing on how light disseminates across a surface. Meanwhile, NEMA types concentrate on specific beam angles, ideal for targeted and precise lighting both indoors and outdoors. Understanding both classifications is essential for selecting appropriate lighting fixtures for any project.

Comparing IESNA and NEMA Classifications by Beam Angle

IESNA (Illuminating Engineering Society of North America) and NEMA (National Electrical Manufacturers Association) offer distinct methods for describing how light spreads from a fixture. Here’s a closer look at each:

IESNA Classifications

IESNA organizes light distribution into five primary types (I to V), focusing on the horizontal spread of light. This is particularly relevant for outdoor environments such as roadways and parking lots. IESNA measures where the light reaches 50% of its maximum intensity, which helps determine the spread of light relative to the fixture’s mounting height. Type I is designed for narrow paths, while Type V covers broad circular areas.

NEMA Classifications

Conversely, NEMA classifications consider both vertical and horizontal beam angles, essential for precision in directional lighting like floodlights and spotlights. NEMA quantifies beam spread in degrees and defines the angles at which light intensity is at 50% and 10% of the maximum, allowing for tailored lighting control based on specific needs.

Key Differences Summarized:

• Measurement Approach: IESNA gauges horizontal dispersion at half-maximum intensity, whereas NEMA specifies exact angles where light reaches 50% and 10% intensity.
• Application Focus: IESNA is suited for broad area lighting across expansive spaces, while NEMA targets more precise, directional lighting scenarios.
• Classification Types: IESNA classifications are based on the pattern of light distribution, and NEMA classifications detail specific beam angles for targeted applications.

How Many NEMA Street Light Distributions Are There?

NEMA categorizes beam spreads into seven distinct types, ranging from very narrow to very wide. Understanding these types helps in selecting the appropriate lighting for varying distances and spaces, streamlining the process for outdoor and industrial applications. This classification system not only facilitates choosing the right lighting but also contributes to energy efficiency and optimal illumination.

What is the Best Beam Angle for Landscape Lighting?

The optimal beam angle for landscape lighting depends on the size of the area and the extent of illumination required. Narrow beam angles are perfect for spotlighting specific features, while wide beam angles are ideal for illuminating larger spaces. Matching the beam angle with the mounting height and the area’s dimensions enhances both the aesthetics and functionality of your outdoor lighting.

What is the Distribution of Light in All Directions?

Type V distribution emits light in a circular pattern, making it highly effective for expansive areas such as intersections and large parking lots. This omnidirectional spread ensures uniform illumination, eliminating dark spots and enhancing safety and visibility throughout the area.

How to Read a Lighting Distribution Diagram?

A lighting distribution diagram, also known as a photometric curve, illustrates the directional spread of light from a fixture. Learning to interpret these diagrams is crucial for determining how light disperses, aiding in strategic placement of fixtures to achieve desired lighting effects. These diagrams are invaluable tools for precise lighting planning.

Can Light Travel in Different Directions?

Yes, light can be directed in various patterns through specific fixture designs and installation techniques. Adjustable lighting is essential for applications such as street and architectural lighting, where precision in directionality enhances visibility, safety, and aesthetic appeal.

What is the Difference Between C0 and C90?

C0 and C90 are terms used in photometric plans to indicate light distribution angles—C0 runs along the length of the luminaire, and C90 is perpendicular to it. Understanding the difference between these angles is crucial for effective light placement and ensuring optimal directional light coverage in an environment.

Stellar LED Street Light Distributions Type II

What is the Distribution of Light Called?

Light distribution from fixtures is classified into five types (I, II, III, IV, V), each describing the direction and spread of light. These classifications assist in selecting the right type of lighting, optimizing light usage, and maximizing efficiency in various settings.

Conclusion

Selecting the correct light distribution type is vital for effective lighting across different environments. Each distribution type offers specific advantages for various applications, ensuring efficient and targeted illumination. For additional information or personalized lighting solutions, contact us at Logos Lighting.