Nema Beam Spread: Understanding Lighting Distribution

Understanding NEMA Lighting Classifications

NEMA (National Electrical Manufacturers Association) lighting classifications help lighting professionals select the right fixtures for specific applications. Founded in 1926, NEMA is an ANSI-accredited organization that develops standards for electrical equipment used in North America, including comprehensive lighting distribution standards.

These classifications are essential for designing effective lighting systems that meet safety requirements, efficiency standards, and performance expectations for commercial and industrial applications.

NEMA Beam Spread Classifications

NEMA classifies lighting fixtures by beam spread angle and approximate projection distance. These classifications range from Type 1 (very narrow) to Type 7 (very wide). Understanding these classifications helps specify the right fixture for mounting height and coverage requirements.

• Very Narrow (NEMA Type 1)
  • Beam Spread: 10° to 18°
  • Typical Projection Distance: 240+ feet
  • Applications: Long-throw applications, accent lighting
• Narrow (NEMA Type 2)
  • Beam Spread: 18° to 29°
  • Typical Projection Distance: 200-240 feet
  • Applications: Perimeter lighting, security applications
• Medium Narrow (NEMA Type 3)
  • Beam Spread: 29° to 46°
  • Typical Projection Distance: 175-200 feet
  • Applications: LED parking lot lights, medium-height applications
• Medium (NEMA Type 4)
  • Beam Spread: 46° to 70°
  • Typical Projection Distance: 145-175 feet
  • Applications: General area lighting, roadways
• Medium Wide (NEMA Type 5)
  • Beam Spread: 70° to 100°
  • Typical Projection Distance: 105-145 feet
  • Applications: Wide area coverage, lower mounting heights
• Wide (NEMA Type 6)
  • Beam Spread: 100° to 130°
  • Typical Projection Distance: 80-105 feet
  • Applications: LED flood lights, wall washing
• Very Wide (NEMA Type 7)
  • Beam Spread: 130°+
  • Typical Projection Distance: Under 80 feet
  • Applications: Close-range area lighting, under-canopy applications

Note: Projection distances are approximate and vary based on fixture design, lumen output, and specific photometric characteristics. Consult photometric data for precise performance specifications.

NEMA Light Distribution Pattern Types

In addition to beam spread classifications, NEMA defines six standard light distribution patterns for roadway and area lighting applications. Each pattern type addresses specific geometric lighting requirements.

Type I Distribution

• Pattern: Two-way 15° lateral distribution
• Applications: Sidewalks, paths, walkways
• Fixture Placement: Center-mounted
• Mounting Height Guidelines: Approximately equal to walkway width

Type II Distribution

• Pattern: 25° lateral distribution
• Applications: Narrow roadways, wide walkways, ramps, entrance roads
• Fixture Placement: At or near roadway side
• Mounting Height Guidelines: Road width should not exceed 1.75 times the mounting height

Type III Distribution

• Pattern: 40° lateral distribution
• Applications: General roadways, parking areas
• Fixture Placement: Side-mounted
• Mounting Height Guidelines: Road width should not exceed 2.75 times the mounting height

Type IV Distribution

• Pattern: 60° semicircular distribution
• Applications: Wide roadways, wall-mounted applications
• Fixture Placement: Side-mounted
• Mounting Height Guidelines: Road width should not exceed 3.7 times the mounting height

Type V Distribution

• Pattern: 360° circular distribution
• Applications: Intersections, center medians, large parking areas
• Fixture Placement: Center-mounted
• Characteristics: Equal light distribution in all horizontal directions

Type VS Distribution

• Pattern: 360° square distribution
• Applications: Intersections, center medians, defined boundary areas
• Fixture Placement: Center-mounted
• Characteristics: Square light pattern with more defined edges than Type V

Selecting the Right Distribution

Choosing the appropriate NEMA classification depends on several factors:

• Mounting Height: Higher mounting on light poles allows wider distribution patterns
• Coverage Area: Narrow beams for distant targets, wide beams for close, broad coverage
• Application Requirements: Security lighting may require different patterns than general area lighting
• Spacing and Layout: Fixture spacing affects overlap and uniformity

For optimal results, lighting design should be based on photometric analysis and may require consultation with lighting professionals to ensure proper illumination levels, uniformity, and compliance with local codes.

Professional Installation Note: Electrical installations should be performed by qualified electricians in accordance with local electrical codes and regulations. Proper permits and inspections may be required.