Mayfield Electric & Water Systems maintains a tree trimming program to promote public safety, reliable service, and cost control.
Mayfield Electric & Water Systems recognizes and appreciates that trees are valuable assets to our customers' landscapes and to the quality of life in our area. However, this must be balanced with the constant threat to our customers' electric service posed by trees. In addition to outages, downed wires threaten the safety of people and animals and increase the cost of providing utility service.
Public safety, reliable service, and cost control are all important to us. That is why MEWS maintains a program of tree trimming and removal. Tree crews operate nearly year round to clear the lines to reduce tree related outages and to expedite service restoration during storms.
There are several issues that we are often questioned about concerning tree trimming activities.
2009 Tree Trimming Policy Information
Reasons for Trimming
Trees must be trimmed to prevent contact between lines and tree limbs shorting out and causing outages. Trees conduct electricity and they are connected to the ground. Electric power wants nothing more than to get to the ground though any available path. Electric wires running along poles are bare and isolated from paths to ground at each pole by insulators; but, when a tree branch touches a wire, electricity gets to do what it wants . . . it flows through the tree to ground. When this happens, one of our fuses or circuit breakers trips to interrupt the faulty flow to ground and your power goes off.
"Climbable" trees near the lines must also be trimmed on a regular basis to prevent children from climbing the trees and coming into contact with the conductors. Limbs overhanging primary lines must be pruned because they fall on the lines during storms and cause extensive outages. Backlot lines and rural rights-of-way need to be cleared or bushhogged to provide access for crews performing routine maintenance on the system or for service restoration in emergencies. Poles need to be clear of brush and trees so that linemen may safely climb them to perform their jobs.
The only economically tractable solution to the tree problem is for us to trim trees in such a manner that they do not provide electric power a path to ground.
Method of Trimming
Mayfield Electric & Water Systems uses only "lateral" or "directional" tree trimming methods according to ANSI A-300 standards. This is the voluntary standard for all tree work in the United States. Lateral trimming means that limbs are removed at their nearest main branch or to the trunk of the tree, and not simply cut to a "stub." Read more about lateral trimming below.
MEWS does not top, tip, or roundover trees unless it is absolutely necessary. This sort of "topping," "shrubbery style," or "rounding over" trimming may result in nicer looking trees, but it also results in fewer healthy trees. These techniques have many cuts between nodes which results in damage to the trees’ health and encourages prolific sprouting. Cutting a tree branch in the middle of its length results in dozens of weak new branches being output by the tree at those cuts. Those multiple cuts also cause weakness of the new branches and multiple avenues for disease and insects to enter the tree. Please read The International Society of Arboriculture's article for more information on "Why Topping Hurts Trees."
Lateral tree trimming has been endorsed by industry experts including The National Arbor Day Foundation and The International Society of Arboriculture as the best method of line clearance for the health of the trees. Although some trees’ appearance may be considered unusual after the initial trim, it quickly improves with time and growing seasons. Trees that have been lateral trimmed for three or more cycles (10 years) are considerably healthier than their counterparts that have been "rounded-over" or "topped."
Lateral Trimming
Utility companies and professional arborists now agree. The best way to trim trees, for the tree's health and for maintaining reliable electric networks, is to use a method called "directional" or "lateral" trimming.
Directional or lateral trimming strives to train the tree to grow away from and around the wires. These trimming principles were developed by the U.S. Forest Service and are endorsed by The International Society of Arboriculture (a world recognized group of experts in tree health) as well as tree care professionals across the country. This method can best be described as trimming the limbs that are growing in the direction of neighboring electric wires all the way back to their "parent" limb. Limbs growing into the utility space are removed and those limbs growing away from or parallel to the conductors remain. Limbs are removed to crotches within the crown of the tree and if more than 50% of the foliage of a limb must be removed, then it is removed in its entirety. This method satisfies the clearance requirements for MEWS as well as the health needs of the tree and leaves virtually no limb stumps which can issue new sprouts in the direction of our lines. Wherever possible, the trees are allowed to achieve their normal mature height with crown development away from the conductors. Severe crown reduction practices are only used with trees located directly beneath the conductors.
These trimming techniques give some trees an unusual appearance when viewed from the side. The trees are viewed from one pole to the next. When viewing the tree from the house or the street, it will have the a normal shape and size of crown for that species of tree.
The figure below is a very good representation of the directional or lateral trimming method.
Amount of Clearance
In all situations, trees near primary lines should be trimmed before they actually touch the lines and enough clearance must be obtained so that the trees do not grow back into the lines before the crews make the cycle and trim them again. The exact amount of clearance obtained at any given site varies considerably and is dependent on the voltage and construction of the line, the sagging of the conductors at elevated temperatures, the combined movement of the lines and trees during adverse weather conditions, the normal re-growth of the species of tree involved, and the position of the tree in relation to the lines.
Tree Removal
Mayfield Electric & Water Systems will remove trees that are directly beneath the lines or so close to the lines that they require severe trimming. The limbs will be chipped and hauled away and the trunk and larger limbs will be cut to whatever length the trees’ owner desires. The stump will be ground and removed. The wood will not be split or hauled away.
Trees along the edge of the right-of-way that are severely leaning, dead, decayed, or otherwise hazardous to the lines may be removed. MEWS reserves the right to refuse to remove any tree which in its judgment can be safely removed by a private tree worker with no damage to our lines.
Debris Disposal
Slash from line clearing operations in wooded areas may be left on the ground or mulched with a bushhog. In and adjacent to maintained areas the debris will either be chipped or mulched with a bushhog. Debris in lawns will be chipped and hauled away. Debris generated as a result of storms and storm restoration is not cleaned up by MEWS.
If you would like to have some of these chips for mulch or compost, MEWS is currently working in conjunction with the Mayfield Public Works Department to offer these chips during specific times. ***********
The chips may attract bees or insects during warm weather and they may stain sidewalks or driveways if they are left on them for an extended period. The chips should also be allowed to decay for several months before the are used as mulch or they may cause sensitive plants to turn yellow temporarily.
Services and Private Lights
Trimming for services to residences and private lights as well as trimming for light pattern is the responsibility of the customer. We will trim your service if you request it while we are routine trimming in your area. The service will only be cleared of touching branches and neither trees or large limbs over the service will be removed.
If you or a private tree worker hired by you feel that it is unsafe to work close to the service, then call our main office during regular business hours to schedule a lineman disconnect your service and re-install it after the tree work is complete. There is no charge for this. Trees or limbs that are broken onto the services during storms will be cut off by MEWS, or the service may simply be re-installed over the tree, depending on the conditions.