Lighting guidelines in Johnston do not specify pole heights or fixture locations, but instead stress the importance of uniform lighting design with a respect for adjacent properties.
When site plans are submitted for review, a photometric plan on a 10-foot grid illustrating the proposed illumination at ground level is also required which includes all exterior fixtures.In addition, manufacturers’ information sheets are required on the proposed lighting materials.
City staff review a submittal for the following:
- The maximum average illumination value adopted by the city for high activity areas is 1.5 times the Illumination Engineering Society (IES) guideline.
- The uniformity ratio (average:minimum) may not exceed 6:1 for high activity areas.
- The ratio of maximum:minimum may not exceed 20:1.
- The trespass light level at the property line shall not exceed the standard for the proposed activity level on adjacent property.
- Tilting of fixtures is prohibited.Use of floodlights is prohibited except for architectural emphasis.
- Cut-off fixtures must shield the light source at an angle of 90-degrees from vertical (no light spill above this angle) for any light source greater than 2,000 lumens (150 watts).
- Illumination under a canopy may be up to 25 foot candles.
For more information, contact the Community Development Department.