Routine Maintenance Improves Reliability
​​​​​​​​​Trees and other vegetation are key contributors to approximately 20-30% of all electric service interruptions. Preventive pruning helps keep trees and power lines a safe distance apart. Areas where line clearance work is completed experience fewer outages and a significant improvement in electric reliability.
Our vegetation management crews are trained in proper arboricultural pruning techniques which meet the standards set by the American National Standards Institute (ANSI). These techniques take into account the species and location of the tree in relation to the overhead wires as well as the overall health of the tree.
Pruning trees near power lines is dangerous. Pepco's contractors are specially trained to work in close proximity to electrical conductors. Please see Tree Pruning for additional information.​
Transmission and Distribution Vegetation Maintenance
Pepco maintains two distinct types of overhead electric facilities. Electric transmission rights-of-way contain facilities that carry power from power generation stations to substations; electric distribution easements contain facilities that carry power from substations to customers.
Pictured above is an example of an electric transmission facility.
Electric Distribution Vegetation Maintenance​
Scheduled Maintenance​​
Pepco performs routine tree and vegetation maintenance on regular cycles. These cycles are four years in length for distribution facilities.Pepco also performs some off-cycle work where preventative maintenance is needed.
Standards and Pruning Technique
Pepco performs pruning to provide clearance from the overhead facilities. This work is done in many cases to direct the tree growth away from the facilities and is often referenced as directional pruning.
The pruning clearances to which we hold our contractors are based on the growth rate and size and shape of each tree, the location of the tree in relation to the power line, the type of utility facility, and a cycle length of 4 years. These clearances are in accordance with the Maryland RM 43 mandated requirements.
Shown above, directional pruning guides the growth of the tree away from the wires.
Pepco does not practice "topping" or "rounding over" of trees. That method can cause a flush of fast growing ​sprouts that grow directly back into the wires. To learn more about avoiding and reducing tree and utility conflicts, visit the International Society of Arboriculture and the Arbor Day Foundation website.
Electric Transmission Right-of-Way Maintenance
Powering lives begins with a journey that transports high-voltage electricity from power generation stations, to substations that "step down" the voltage to a level that can be distributed to your home.
Transmission rights-of-way (ROW) typically contain large steel poles or tower structures that are used to transport high-voltage electricity across large distances. In some instances these ROW may contain large wood poles or wood pole structures. Pepco has the right by easement or fee ownership to perform vegetation management on and adjacent to transmission ROWs in our service territory. Where feasible or required, Pepco uses a technique called integrated vegetation management to make sure that trees and other vegetation never cause an interruption to the system from within the ROW. Additionally, Pepco also performs pruning on trees outside of the ROW to minimize the likelihood of trees falling onto or near these critical facilities
Federal Mandates
Federal standards mandate that utilities have a transmission vegetation management program to prevent widespread outages on the transmission system. The North American Electric Reliability Corporation (NERC.com) strictly enforces these standards. The Federal Energy Regulatory Commission (FERC) has specific guidelines and requirements that electric utilities must meet. Visit the FERC website for more information.
Acceptable Vegetation
Pepco only allows shrubs and low-growing trees on its electric transmission rights-of-way. Pepco does not prune trees to maintain them within electric transmission rights-of-way; incompatible growing trees and other vegetation are removed.
It is required that you contact Pepco if you are considering planting any vegetation within an electric transmission right-of-way. Pepco encourages the establishment of native prairie grasses and flowers in a ROW's Wire and Border Zones, and fosters plant species that support pollinator insects.
Check out our interactive map of where Pepco is performing maintenance.
U.S. Fish & Wildlife Service​
Maryland Department of Natural Resources
The International Society of Arboriculture
The National Arbor Day Foundation
University of Maryland Cooperative Extension Service
Mid Atlantic Chapter of the International Society of Arboriculture
Tree Care Industry Association (for ANSI Standards)
National Association of State Foresters​