November 15, 2007 -- Blount County Commission Passes Commercial Lighting Regulation


On November 15, 2007, the Blount County Commission passed the following change to the county's zoning resolution pertaining to commercial lighting.

Blount County Zoning Resolution 

Section 7.14. Design Requirements for Commercial and Industrial Developments.......


D. Outdoor Lighting Standards. Outdoor lighting is important for night visibility, safety, and security. Outdoor lighting can, however, also invade privacy and cause nuisance if excessive glare and direct light trespasses on adjacent properties. These requirements ensure that new development minimizes the amount of light that may shine on abutting properties. The following is required when installing lights:


1. A lighting plan may be required (as determined by the Building Commissioner or reviewing body);


2. A light "point by point" footcandle diagram must be shown on the site plan with a 10x10 foot maximum grid. The diagram should cover at least ten feet on either side of property lines that border residential zones or uses;


3. Lighting must not exceed 0.5 footcandle at or beyond the property line zoned or used for residential purposes;


4. Any luminaire with lamp(s) rated at a total of more than 1800 lumens, and any flood or spot luminaire with lamp(s) rated at a total of more than 900 lumens shall not emit any direct light above a horizontal plane through the lowest direct light emitting part of the luminaire (full cut-off);


5. Laser source lights or any similar high intensity light for outdoor advertising or entertainment is prohibited; and


6. The operation of searchlights for advertising purposes is prohibited.


This verbiage starts on page 78 of the November 15, 2007, proceedings of the Blount County Commission (3.9 MB PDF).


The posting plus comments is here.


Excerpt from Planning Board Memorandum Elaborating on the November 15, 2007 Commercial Lighting Regulation


Following is an excerpt from an October 17, 2007, memorandum written by John Lamb, Planning Director for Blount County, substantially elaborating on the new amendment to the Blount County Zoning Resolution concerning commercial lighting. [Our webmaster apologizes for not supplying the link to this memo, but our current web authoring tool is not compatible with the symbols in the link; for more info, please email us.] 

"The Planning Commission indicated that the [wording of the commercial lighting regulation that was eventually passed on November 15th] was a stop-gap measure to allow the remainder of design standards for commercial developments to be considered in a timely manner by the County Commission.... Staff was directed to expand an alternate set of regulations on outdoor lighting for consideration at the October meeting. The following combines the original proposal (alternative 1) is last month’s staff memo, and a set of additional considerations handed out at the last meeting. Staff also changed the wording to define qualified professionals to include electrical engineer, certified lighting contractor, and electrical contractor qualified in lighting, based [on] discussions at the last meeting.

D. Outdoor Lighting Standards. In both rural and urban settings, proper design of commercial lighting is important in order to address impacts on surrounding properties and the character of the community. A complete lighting plan shall be part of site plan documents, and the site plan approval body (Planning Commission or Board of Zoning Appeals) may set appropriate conditions for spill light mitigation during site plan review and approval. The following apply particularly to new commercial developments, and shall also be applied to substantial additions or expansions to existing developments. All lighting structures in existence prior to adoption of these regulations are exempt from further regulations, provided that replacement of structures shall meet all of these regulations.

1. Maximum spill light (light trespass) at perimeter of a commercial property shall be subject to the following performance standards and requirements:

For locations in the Urban Growth Boundary of Maryville and Alcoa as defined in the 1101 Growth Plan, maximum spill light shall be no greater than 0.8 footcandles. For locations in the Rural Areas as defined in the 1101 Growth Plan, maximum spill light shall be no greater than 0.4 footcandles.

2. Lighting Plan. A qualified professional, either electrical engineer, certified lighting contractor, or electrical contractor qualified in lighting plans and installation, shall prepare and certify a lighting plan conforming to requirements in these regulations. All lighting plans shall follow standards for footcandle output as established by the Illuminating Engineering Society of North America (IESNA). A light “point by point” footcandle diagram shall be shown on the site plan with a 10x10 foot maximum grid. The diagram shall cover at least ten feet on either side of property lines that border residential zones or uses. The qualified professional who prepares the lighting plan shall inspect the installation of all lighting equipment, and conduct a performance verification to measure spill light illuminance levels of all lighting after lighting installation, to include night-time field measurements of spill light at a vertical height of 6 feet from ground level at points spaced no greater than fifty feet apart along the perimeter of the commercial property, and at points along the perimeter closest to lighting fixtures. Where lighting installation does not meet required performance standards, the qualified professional shall coordinate adjustment of the lighting installation to meet such standards and

again conduct performance verification measurements specified above. Upon completion of installation, inspection of installation, and performance verification measurements (with any necessary adjustments), the qualified professional shall submit a drawing showing the final measured spill light illumination levels specified at points along the perimeter identified above, with professional stamp and signed certification letter that lighting installation and performance meets all applicable standards and the approved site plan. For phased installation of lighting, new measurements for all lighting, drawing, and certification shall be required for each phase as specified above.

3. All lighting structures of greater than 1000 lumens shall be full cut-off type, mounted facing to the ground with no upward angle, to minimize unnecessary scattering of light. All lighting structures shall be designed and placed so as to minimize light spill and glare to surrounding residential properties.

4. The site plan for lighting shall include all lighting pole locations and luminaire mounting heights, all security and safety lighting structures, and projected spill light illuminance and glare of all lighting combined at commercial property perimeter, meeting standards above. Means for minimizing and mitigating glare shall be part of the lighting plan submitted for site plan review and approval. No light shall be mounted at height greater than 20 feet.

5. Tall shrubs and trees may be considered as screens to reduce glare and spill light.

6. External lighting of the face of signs or walls of structures shall be placed above the sign or wall and shielded. Sign or wall lighting shall not reflect or glare beyond the face of the sign or wall.

7. Uplighting is prohibited except in cases where the fixture is shielded from the sky by a roof overhang or similar structural shield, and where the fixture does not cause light to extend beyond the structural shield. Exempt from this is lighting of governmental flags only, provided that the combined lighting is no more than 1300 lumens, and provided that the fixtures shall be shielded such that the lamp(s) is not visible outside a 15 foot radius.

8. Flashing or intermittent lights, lights of changing degree of intensity, or moving lights shall not be permitted, provided that holiday lights are exempt, and provided that necessary emergency and tower lighting is exempt, and provided that lighting cut-off or dimming at close of business is exempt and encouraged, and provided that sensor activated security lighting is exempt and encouraged.

9. Luminaires that have a maximum output of 260 lumens per fixture, regardless of number of bulbs, (equal to one 20 watt incandescent light), may be left unshielded provided that the fixture has an opaque top to keep light from shining directly up. Luminaires that have a maximum output of 1,000 lumens per fixture, regardless of number of bulbs, (equal to one 60 watt incandescent light) may be partially shielded, provided the bulb is not visible, and the fixture has an opaque top to keep light from shining directly up.

10. Canopy lights – all lighting shall be recessed to full cut-off standard and recessed sufficiently so as to ensure that no light source is visible from or causes glare on public rights-of-way or adjacent property.

11. All non-essential exterior commercial lighting is to be turned off after business hours and when not needed. Lights with timer installed are encouraged. Sensor activated lights are encouraged to replace lighting that is desired for security purposes.

12. Sports lighting – sports field lighting fixtures shall be mounted no higher than 90 feet, provided that such sports field light fixtures shall be a distance 40 feet or height of pole whichever is greater from any adjacent residential or residentially zoned property boundary, and provided that no outside sporting event shall start after 10:00 p.m. or extend beyond 11:00 p.m. with all field lights out by 11:30 p.m., and provided that sports fields shall provide tall vegetative or other acceptable buffering from adjacent properties in order to reduce and mitigate glare.

13. Temporary lighting such as that used at construction sites or other uses of a temporary nature are exempt, provided that the temporary lighting shall be aimed so as to minimize glare and light trespass to adjacent properties, turned off after 11:00 p.m. (except for necessary security lighting), and turned off after completion of project."