Morrisville Unified Development Ordinance - June 2017

Article 5: Development Standards Section 5.15. Exterior Lighting 5.15.3. Parking and Outdoor Lighting Light Levels

C. Measurement of Light Levels Light levels are specified, calculated, and measured in maintained foot-candles (i.e., include a maintenance factor for dirt build-up and lamp lumen depreciation) unless specified otherwise. Measurements of light levels shall be taken with a light meter that has been calibrated within two years. They shall be taken at finished grade (ground level), with the light-registering portion of the light meter held parallel to the ground and pointing up. The meter shall have cosine and color correction and an accuracy tolerance of no greater than plus or minus five percent. A. Light Levels and Uniformity Ratios for High Pressure Sodium (HPS) and Metal Halide (MH) Lighting Exterior light levels for high pressure sodium (HPS) and metal halide (MH) lighting shall comply with standards in Table 5.15.3, Light Levels and Uniformity Ratios for High Pressure Sodium (HPS) and Metal Halide (MH) Lighting, for the type of lighting. Table 5.15.3: Light Levels and Uniformity Ratios for High Pressure Sodium (HPS) and Metal Halide (MH) Lighting 5.15.3. Parking and Outdoor Lighting Light Levels

Light Level (foot-candles) [1][2]

Average Light Level to Minimum Light Level Uniformity Ratio

Type of Lighting

Maximum

Average

Minimum

Anchor Tenant in a Major or Neighborhood Shopping Center

n/a

4.0

0.2

4:1

Loading Dock

n/a n/a

3.0 3.0 n/a n/a

0.2 0.2 0.2 0.2

4:1 4:1 5:1 4:1

Nonresidential Parking Lot

Vehicle Sales

20.0 20.0

Vehicular Canopy

Notes: n/a = not applicable

[1] Maximum and average light levels shall be a horizontal measurement at grade or ground level of light level points on a ten-foot by ten-foot point-by-point layout grid in the overall lighted area. They shall be a not-to-exceed value measured or calculated using only the area of the site intended to receive illumination. [2] Measurements and calculations for a new system (after 100 hours of burn-in) shall be multiplied by a maintenance factor of not greater than 0.72 foot-candles for high pressure sodium lighting and 0.64 for metal halide lighting to determine compliance with the standards in this table. For example, if a maximum point measurement of 23 foot-candles was taken on a vehicle sales lot for a new metal halide lighting system, then 23 x 0.64 = 14.72 foot-candles. B. Light Levels and Uniformity Ratios for Light Emitting Diode (LED) Lighting Exterior light levels for Lighting Emitting Diode (LED) lighting shall comply with standards in Table 5.15.3.B: Light Levels and Uniformity Ratios for Light Emitting Diode (LED) Lighting, for the type of lighting.

Morrisville, NC

June 23, 2017

Unified Development Ordinance

Page 5-141