UpCodes logo
Go To Full Code Chapter
17.3.5.1 Electrical Transmission Lines
17.3.5.1.1
Clearance of brush and vegetative growth from electrical transmission and distribution line(s) shall be provided and maintained in accordance with 17.3.5.1.
17.3.5.1.2
A combustible-free space around poles and towers shall consist of a clearing of not less than 10 ft (3.05 m) in each direction from the outer circumference of the pole or tower during such periods of time as designated by the AHJ.
17.3.5.1.3 Trimming Clearance
17.3.5.1.3.1
At the time of trimming, clearances not less than those established by Table 17.3.5.1.3.1 shall be provided.

Table 17.3.5.1.3.1 Minimum Clearances Between Vegetation and Electrical Lines at Time of Trimming
Line Voltage Minimal Radial Clearance from Conductor
ft m
2400—72,000 4 1.2
72,001—110,000 6 1.8
110,001—300,000 10 3.0
300,001 or more 15 4.6
17.3.5.1.3.2
The radial clearances in Table 17.3.5.1.3.1 are minimum clearances that shall be established at time of trimming between the vegetation and the energized conductors and associated live parts.
17.3.5.1.4
Clearances not less than those established by Table 17.3.5.1.4 shall be maintained during such periods of time as designated by the AHJ.

Table 17.3.5.1.4 Minimum Clearances Between Vegetation and Electrical Lines to Be Maintained
Line Voltage Minimum Clearance
ft m
750—35,000 6 152
35,001—60,000 12 305
60,001—115,000 19 483
115,001—230,000 30.5 775
230,001—500,000 115 2920
17.3.5.1.4.1
The site-specific clearance achieved, at the time of pruning, shall vary based on species' growth rates, the utility company specific trim cycle, the potential line sway due to wind, line sway due to electrical loading and ambient temperature, and the tree's location in proximity to the high voltage lines.
17.3.5.1.4.2
The AHJ shall establish minimum clearances different than those specified by Table 17.3.5.1.4 when evidence substantiating such other clearances is submitted to the AHJ and approved.
17.3.5.1.5* Electrical Power Line Emergencies
During emergencies, the utility company shall perform the required work to the extent necessary to clear the hazard.
17.3.5.2 Structures
17.3.5.2.1
Persons owning, leasing, controlling, operating, or maintaining buildings or structures in, upon, or adjoining hazardous fire areas, and persons owning, leasing, or controlling land adjacent to such buildings or structures, shall maintain an effective defensible space in accordance with 17.3.5.2.1.1 through 17.3.5.2.1.11.5.
17.3.5.2.1.1*
Ground fuels, including native vegetation and plants used for landscaping within the defined landscaping zones, shall be treated or removed. (1144:6.2.1]
17.3.5.2.1.2
Live vegetation within the fuel modification area shall have dead material removed and shall be thinned and pruned in conformance with the wildland fire mitigation plan, as approved by the AHJ. [1144:6.2.2]
17.3.5.2.1.3
Dead and downed fuels within 30 ft (9 m) of all buildings shall be removed or treated to maintain the fuel modification area in conformance with the wildland fire mitigation plan, as approved by the AHJ. [1144:6.2.3]
17.3.5.2.1.4
Vegetation under trees within the fuel modification area shall be maintained at a height that will preclude ground fire from spreading in the tree crown. [1144:6.2.4]
17.3.5.2.1.5*
Tree crowns within the structure ignition zone shall be spaced to prevent structure ignition from radiant heat. [1144:6.2.5]
17.3.5.2.1.6
The fuel modification plan shall include a maintenance element identifying and defining the responsibility for continued and periodic maintenance. [1144:6.2.6]
17.3.5.2.1.7 Chimneys and Flues
17.3.5.2.1.7.1
Every fireplace and wood stove chimney and flue shall be provided with an approved spark arrester constructed of a minimum 12-gauge welded wire or woven wire mesh, with openings not exceeding 1/2 in. (12.7 mm). [1144:5.8.1]
17.3.5.2.1.7.2
Vegetation shall not be allowed within 10 ft (3 m) of a chimney outlet. [1144:5.8.2]
17.3.5.2.1.8* Accessory Structure(s)
Accessory structures shall be constructed to meet the requirements of Chapter 5 of NFPA 1144 or shall be separated from the main structure by a minimum of 30 ft (9 m). [1144:5.9]
17.3.5.2.1.9 Mobile and Manufactured Homes
17.3.5.2.1.9.1
Permanently located mobile and manufactured homes with an open space beneath shall have a skirt of noncombustible materials, exterior fire-retardant-treated wood, or other ignition-resistant material. [1144:5.10.1]
17.3.5.2.1.9.2
Any enclosed space beneath the mobile or manufactured home shall be vented according to 5.2.2 of NFPA 1144. [1144:5.10.2]
17.3.5.2.1.10 Vehicle Parking Areas
Vehicle parking areas within the immediate landscaped zone shall be maintained free of dry grasses and fine fuels that could be ignited by hot exhaust systems or firebrands. [1144:5.11]
17.3.5.2.1.11 Exterior Exposure Hazards
17.3.5.2.1.11.1*
Heat and flame sources that are unprotected or unsupervised shall not be permitted within 30 ft (9 m) of the primary structure. [1144:5.12.1]
17.3.5.2.1.11.2
Incinerators, outdoor fireplaces, permanent barbecues, and grills shall not be built, installed, or maintained in hazardous fire areas without prior approval of the AHJ. [1144:5.12.2]
17.3.5.2.1.11.3
Openings in incinerators, outdoor fireplaces, permanent barbecues, and grills shall be provided with an approved spark arrester, screen, or door. [1144:5.12.3]
17.3.5.2.1.11.4
Propane tanks and other combustible liquids storage shall conform to NFPA 58 and the wildland fire hazard mitigation plan required in 17.1.10. [1144:5.12.4]
17.3.5.2.1.11.5
Other combustible materials within 30 ft (9 m) of any structure shall be removed or stored in conformance with the wildland fire hazard mitigation plan as approved by the AHJ. [1144:5.12.5]
17.3.5.2.2
Where required by the AHJ because of extra hazardous conditions, additional areas shall be maintained to include additional defensible space from buildings or structures, trees adjacent to or overhanging a building shall be maintained free of deadwood, and the roof of a structure shall be free of leaves, needles, or other dead vegetative growth.
17.3.5.3 Roadways
Areas within 10 ft (3 m) on each side of portions of highways and private streets shall be cleared of combustible vegetation and other combustible growth. Single specimens of trees, shrubbery, or cultivated ground cover such as green grass, ivy, succulents, or similar plants used as ground covers shall be permitted to be exempt provided that they do not form a means of readily transmitting fire.

Related Code Sections

17.3.5 Wildland Urban Interface, Clearance of Brush and Vegetative Growth
Clearance of brush and vegetative growth from electrical transmission and distribution line(s) shall be provided and maintained in accordance ...
17.3.5.2.1.4 Wildland Urban Interface,
Vegetation under trees within the fuel modification area shall be maintained at a height that will preclude ground fire from spreading in the tree ...
17.3.5.2.1.2 Wildland Urban Interface,
Live vegetation within the fuel modification area shall have dead material removed and shall be thinned and pruned in conformance with the wildland ...