PECO is committed to providing customers with reliable electric service. Trees and other vegetation cause about one third of all electric outages. Preventative pruning around aerial power lines is vital to providing reliable electric service.
PECO’s vegetation management crews are trained in proper arboricultural pruning techniques, which meet the standards set by the American National Standards Institute (ANSI). These standards take into account the type and location of the tree in relation to the overhead wires and the health of the tree. PECO notifies property owners prior to work beginning in each community. Areas where line clearance work is completed experience fewer outages and a significant improvement in electric reliability.
PECO maintains two distinct types of electric rights-of-way. Electric transmission rights-of-way carry power from power generation stations to substations, and electric distribution rights-of-way carry power from substations to customers. Find out more about the maintenance of the two types of right-of-way below.
In addition, you can download our factsheet(pdf) to give you a quick view of the different maintenance programs.
Electric Distribution Right-of-Way Maintenance
PECO performs routine tree and vegetation maintenance on regular cycles. These cycles are five years in length. PECO also performs some mid-cycle work where trees are especially fast growing, or there are other problems that may result in interruptions to electric service.
Electric utility pruning is often perceived differently from other types of pruning because the objectives are different. However, when pruning trees in urban and suburban environments, the tools and methods used are similar to those used for other pruning purposes. Likewise, utility arborists are expected to adhere to the same professional standards as other arborists.
PECO employs professional contractors to perform its line clearance work. The work is performed in accordance with American National Standards Institute (ANSI) Standard A300, Part 1: Tree, Shrub, and Other Woody Plant Maintenance – Standard Practices, Pruning.
The type of tree pruning used by PECO is called directional pruning (or natural target pruning). This method is designed to encourage the tree to grow away from the electric lines and has been adopted as a national standard (ANSI A300, Part 1).
The diagram above shows how directional pruning guides the growth of the tree away from the wires.
The diagram above shows how topping or rounding over of trees can cause a flush of fast growing sprouts that grow directly back into the wires.
Find out further information about how to avoid tree and utility conflicts by visiting the International Society of Arboricultures’ website (+).
Electric Transmission Right-of-Way Maintenance
Electric transmission lines carry power from generation stations to substations. They carry high voltages – at PECO these vary between 66,000 volts and 500,000 volts. These lines are extremely sensitive to the proximity of trees and other vegetation. Power outages on electric transmission lines can have far reaching consequences, such as the loss of power to many thousands of customers, or even regional power blackouts. The aim of PECO’s electric transmission right-of-way vegetation maintenance program is to make sure that trees and other vegetation never cause an interruption to the system.
PECO manages its electric transmission rights-of-way as natural meadows and grass lands, using a technique called integrated vegetation management(+). The rights-of-way provide habitat for birds and animals that is otherwise becoming rare in southeast Pennsylvania.
Electric transmission right-of-way showing the wire zone and the border zone.
PECO does not allow tall-growing trees on its electric transmission rights-of-way. PECO does not prune trees to maintain them in electric transmission rights-of-way; incompatible or tall growing trees are removed.
PECO has been a contributing partner in a scientific study into the effects of different management techniques along electric transmission rights-of-way. This study area is located near Green Lane, Montgomery County, PA. PECO uses the results of the study to guide its maintenance techniques. Learn more about the Green Lane study(+).
See what the Federal Energy Regulatory Commission (FERC) has to say about vegetation management