PG&E Commitment: Latest Updates on Wildfire Response and Recovery Effort

Posted on November 2, 2017

PG&E Vegetation Management: What the Law Says

Q: What specific laws and regulations does PG&E follow?

A: PG&E’s Vegetation Management Program reduces electrical outages and wildfire risks, helping improve service safety and reliability to our customers. PG&E and all regulated electric utilities in California are required to prune or clear vegetation close to energized electrical equipment, structures and high-voltage power lines for public safety and electric system reliability.

PG&E follows all applicable vegetation clearance requirements and performs regular power line tree safety activities in accordance with industry standards, guidelines and acceptable procedures that help to reduce widespread outages or fire caused by overgrowth of trees or other vegetation.

Applicable regulations are administered by the North American Electric Reliability Corporation (NERC), Federal Energy Regulatory Commission (FERC), California Public Utilities Commission (CPUC), and the California Department of Forestry and Fire Protection (CAL FIRE). In addition, PG&E is required to report its vegetation management plan for transmission to the California Independent System Operator (CAISO) and follow its plan. Vegetation clearance requirements include:

California Public Utilities Commission (CPUC) General Order 95, Rule 35

State law requires that we maintain our power lines and keep them free from hazards. GO 95, Rule 35, requires an 18-inch clearance be maintained at all times between vegetation and high-voltage power lines between 750 and 22,500 volts (4 feet is required in Santa Barbara County). GO 95, Rule 35 also requires removal of dead, diseased, defective and dying trees that could fall into the lines. The clearance requirements increase dependent on voltage. GO 95, Rule 35, applies to the entire PG&E territory year round, though additional rules apply in a State Responsibility Area (SRA). The SRA is the area of the state where CAL FIRE has primary responsibility for the prevention and suppression of wildland fires.

Public Resource Code (PRC), Section 4292 

This law is administered by the California Department of Forestry and Fire Protection (known as CAL FIRE). PRC 4292 requires that PG&E maintain a firebreak of at least 10 feet in each direction from the outer circumference of the base of non-exempt poles. Non-exempt poles are those poles that have equipment attached that when operating properly have the potential to emit sparks. Limbs within the 10-foot radius of the pole are removed up to 8 feet above ground. All dead branches below the cross arms and within the 10-foot radius must be removed. This applies in the SRA during designated fire season.

Public Resource Code (PRC), Section 4293

This law is administered by the California Department of Forestry and Fire Protection (known as CAL FIRE). PRC 4293 requires a 4-foot clearance be maintained at all times for power lines between 2,400 and 72,000 volts, and a 10-foot clearance for conductors 115,000 volts and above. GO 95, Rule 35 also requires the removal of dead, diseased, defective and dying trees that could fall into the lines. The clearance requirements increase as the voltage increases. This applies in the SRA during designated fire season.

Federal Energy Regulatory Commission (FERC) and North American Electric Reliability Corporation (NERC)

In addition to state requirements, the FERC and NERC require that utilities adopt and maintain minimum clearance standards between vegetation and transmission voltage power lines as part of an approved vegetation management program. These clearances vary depending on voltage. In some cases, the minimum clearances required in state regulations are greater than the federal requirement.

Q: At a high level, what are the vegetation management requirements around electric lines?

A: About specific transmission requirements:

For transmission lines, requirements for keeping lines free from vegetation ranges from 4 to15 feet. We need to maintain clearances throughout the year. The trees identified for work are prescribed for removal or pruning to maintain compliance with applicable state and federal regulations (FAC 003-4, CAISO agreement, PRC 4293, and CPUC GO 95, Rule 35). At the time of pruning, we keep lines free from vegetation at even greater distances in order to maintain clearance throughout the year.

Additionally, when conducting utility tree work, PG&E uses directional pruning, a method recommended by the International Society of Arboriculture, the American National Standards Institute (ANSI) and the Arbor Day Foundation. Directional pruning reduces growth towards the power lines and encourages growth away from the lines. Trees pruned in this way are less susceptible to pests and disease. They may appear unbalanced, but if they are healthy, they will thrive and the appearance will soften over time. Directional pruning allows trees to coexist safely with powerlines.

Learn more here.

About specific distribution requirements:

For primary distribution lines above 750 volts, requirements for clearance range from 1.5 to 4 feet. At the time of pruning, we keep lines free from vegetation at even greater distances in order to maintain clearance throughout the year as required by PRC 4293, and CPUC GO 95, Rule 35.

About Service or Secondary lines:

Under the requirement for Service or Secondary conductors (Below 750 volts), if conductor shows signs of strain or evidences of abrasion from vegetation contact, it must be corrected by reducing conductor tension, rearranging or replacing the conductor, pruning the vegetation, or placing mechanical protection on the conductor(s).

Email Currents at Currents@pge.com.

Comments are closed.

"PG&E" refers to Pacific Gas and Electric Company, a subsidiary of PG&E Corporation.
© 2017 Pacific Gas and Electric Company. All rights reserved.