Fire and Fuels / July 2013: power lines and fire

Power lines are part of the fire environment, especially in the wildland-urban interface. They are a recurring cause of wildfires in California, and along the coast, where lightning fires are rare, power lines are one of the most common ways that wildfires start. For example, power lines were the ignition source for several recent fires in the S.F. Bay Area:

May 10 - Phleger Estate near Woodside, CA - 0.5 acres
June 14 - Highway 1 in Olema, CA - 1.5 acres
July 4 - Mt. Tam near Kenfield, CA - 1 acre

Fortunately, these fires did not start under extreme weather conditions and were quickly suppressed.

A Power Line Fire Prevention Field Guide has been developed for California which includes the public resource code requirements designed to prevent power line fires. The introduction sets the stage for understanding how high winds, in combination with power lines have led to some of California's largest wildfires:

"Electrical power presents an unusual hazard which brings about a mutual concern on the part of Local, State, Federal fire protection agencies and the electric utilities...

The potential exists that power line caused fires will become conflagrations during the long, hot and dry fire season commonly experienced in California. The very same weather conditions that contribute to power line faults also lead and contribute to the rapid spread of wildfire. The most critical of these weather factors is high wind, which is commonly accompanied by high temperatures and low humidity.

High, gusty winds may cause vegetation to sway into power lines, break off limbs or fall into power lines. High winds may also create vibrations in power lines that can lead to stress failures or cause loose connections to separate. Arcing usually accompanies such faults. Automatic Reclosers re-energizing the line into the fault may cause repeated arcing and increase the probability of igniting vegetation."

More...

TOP BANNER PHOTO: Power lines run through a prescribed fire burn unit along Highway 1, south of Olema in Marin County.

A power line fire near Kentfield at the base of Mount Tamalpais started on the 4th of July. Photo by Scott Holland.

Power Lines and Firefighter Safety

Firefighting near power lines adds additional hazards to an already hazardous job. For this reason, safety guidelines have been developed for firefighters such as the following guidance from PG&E:

Treat all downed wire as ENERGIZED conductor. Isolate and deny entry.
Tactics should consider transmission lines to be an exposure requiring protection when threatened by fire. When possible, establish a Control Line to prevent the spread of fire into the area within 100 feet of and parallel to the edge of the outer most phase conductor.
Smoke, ash, and incidental mist from firefighting operations can contaminate the insulators on transmission structures. This contamination may cause a short-circuit to occur at the structure, creating an electrical hazard.
Spot fires that may occur beneath the tower lines, normally do not generate enough smoke to create an electric safety hazard. Spotters should be able to safely work under the tower lines when spot fires are controlled quickly and are at least 100 feet from the main smoke plume passing though the tower lines.
Small burning trees under the tower or steel pole lines that exceed the height of an individual present a real threat of creating a phase-to-ground short. Maintain clearance between the trees and firefighting operations.
The incidental light-colored smoke that has cooled and dropped from the heavy smoke plume represents no threat of being involved in a phase-to-ground short.
When fighting a fire near high-voltage transmission lines, one should never direct the hose stream:

At wires or raise the hose stream above the height of an individual.
Into the heavy plume of smoke that is within 100 feet of the outside conductor.
At burning trees under the lines.

Aerial drops of chemical fire retardant onto electric transmission lines should be avoided. This retardant can contaminate the insulators on a line, leading to arcing and short-circuits.

For complete guidance with illustrations, see Wildfire Fighting Near High-Voltage Electrical Transmission Lines Owned By Pacific Gas & Electric Company.

See also VIDEO by the Salt River Project, Electric Fire: Firefighter Safety Around Power Lines, posted on Wildfire Today.

Vegetation, Wildlife and Power Lines

It is often an interaction with trees or wildlife that causes a power line fire. Wind blown trees may break a line, or birds caught in the lines may get electrocuted and ignite vegetation when they fall. The Edgewood Fire at Phlegar Estate near Woodside involved both vegetation and wildlife. A falling tree branch snapped a line, and a deer was ignited when it crossed into the area electrically charged area. The fire then spread to the surrounding vegetation....

PHOTO: The NPS / S.F. Bay Area fire crew visited the site of the Edgewood Fire at Phlegar Estate where the remains of electrocuted deer were still visible.

Vegetation Management

VIDEO: PG&E Tree Crews Work to Prevent Power Outages and Wildland Fires

PG&E has a large vegetation management program that helps reduce the risk of fire associated with its electrical operations throughout Central and Northern California. They inspect all of their 120,000+ miles of utility lines for vegetation clearance. In addition, PG&E's Public Safety and Relability Program (PS&R) conducts pro-active tree work focused on fire risk reduction.

The PS&R program uses historic outage data to pinpoint species and locations where trees are most likely to drop limbs or fall into power lines. They are also piloting fire-risk computer modeling which looks at factors including weather, wind, slope and fuel load to determine where the highest fire risk exists near PG&E power lines. Contractors patrol the pre-determined line sections for problematic trees and prescribe species-specific work in accordance with the failure pattern of the tree.

Wildlife

Avian Power Line Interaction Committee (APLIC)

When wildlife comes in contact with power lines, it may lead to harm, and it may involve fire. Birds in particular are often involved. APLIC was formed in 1989 to address whooping crane collisions with power lines. Since its inception, APLIC has expanded to address a vareiety of avian/power line interactions including electrocutions, collisions and nests.

The mission of APLIC is to lead the electric utility industry in protecting avian resources while enhancing reliable energy delivery. APLIC works in partnership with utilities, resource agencies and the public to:

Develop and provide educational resources
Identify and fund research
Develop and provide cost-effective management options, and
Serve as the focal point for avian interaction utility issue

APLIC members include over 30 electric utilities in the United States and Canada as well as the Edison Electric Institute, National Rural Electrical Cooperative Association, Rural Utilities Service, and U.S. Fish and Wildlife Service. More...

Bay Area Headlines

GGNRA Unveils Draft Fire Plan for Rancho

(Half Moon Bay Review, July 3, 2013)

When Firefighters Should Stop Fighting

(Monterey County Herald, July 7, 2013)

Power Lines Caused Last Week's Mount Tam Fire

(Marin Independent Journal, July 8, 2013)

Service Honors 2 Firefighters Killed in Arizona

(San Francisco Chronicle / AP, July 20, 2013)

Upcoming Events

JULY 17 to SEPTEMBER 17, 2013 - CALIFORNIA FIRE SAFE COUNCIL GRANTS CLEARINGHOUSE 2014 FUNDING CYCLE OPEN - Applications for 2014 grant funds will be accepted through 5:00 pm September 17. Grant writing workshops will be held at several locations. More...

"My heart has been broken into 19 pieces..."

-- expression of loss by an Arizona State Forestry employee regarding the fallen firefighters on the Yarnell Fire.

The Wildland Firefighter Foundation helps families of firefighters killed in the line of duty and assists injured firefighters and their families. They provide financial assistance, immediate and ongoing emotional support, advocacy and recognition to fallen and injured wildland firefighters. This work is made possible by donations to the foundation.

Special Tribute to the Granite Mountain Hotshots

by the Wildland Fire Lessons Learned Center

Sincerely,

Jennifer Chapman

Fire Communication and Education Specialist

S.F. Bay Area National Parks

415-464-5133 TEL

Thanks to all the partners who are working to improve fire safety and restore ecosystem health.