Falling tree limbs and other vegetation interfering with power lines are the Number One cause of power outages in the PSO service area. PSO recently implemented a Reliability Enhancement Plan to sharply reduce tree-related power outages, and improve long-term reliability, all at a modest increase in cost to our customers.
The first step – trimming all vegetation that threatens the reliability of PSO power lines at least once every four years – would add less than seven cents a day to a typical monthly electric bill.
To learn more about PSO's reliability work, see these resources:
Update (see below): OCC Approves PSO Interim Request For Line Clearance Funding
| PSO employees hanging informational tags on trees for sale at nurseries |
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You can help keep the lights on and reduce tree-trimming costs by planting wisely, far enough from power lines to keep trees and other plants from causing trouble as they grow. Please remember to Look Before You Leaf.
You can also view a video from OETA-The Oklahoma Network, with PSO Forestry Supervisor Richard Bewley discussing the problems of trees and power lines, and the things you can do to keep trees a safe and important part of our modern landscape:
Tulsa's This Week at City Hall recently featured a discussion about PSO's vegetation management program, focusing on the efforts primarily in the Tulsa area:
Additionally, the City of Tulsa has published
a tree ordinance with an approved list of small trees that may be planted
within 20 feet of overhead utility wires in that community. You can access
the ordinance at http://www.cityoftulsa.org.
Information on PSO’s Reliability Enhancement Program
- Trees are the leading cause of power outages on PSO’s electric system, including outages of a sustained duration as well as those annoying power “blinks” that cause people to have to go around their home resetting their digital clocks. Just one limb in contact with a power line can disrupt electric service to a thousand customers for hours.
- PSO launched its Reliability Enhancement Plan to reduce the frequency of power outages experienced by our customers.
- At this point in PSO’s reliability enhancement program, we have completed trimming 13 electrical distribution circuits serving approximately 15,000 customers in Tulsa. A look at the reliability performance of these 13 circuits from January through June 2005, compared with the same period last year, shows we are making solid progress in reducing the frequency of power outages experienced by our customers.
- On average, each of the 13 circuits had 1.81 outages during the first six months of last year. Between January and June 2005, those same circuits experienced only .92 outages, or an approximate 50 percent reduction. On one specific circuit, customers benefited from an almost 100 percent reduction in outages this year as compared to 2004.
- In announcing the plan, PSO estimated we can bring about an 80 percent reduction in tree-related outages by achieving a “four-year cycle trim”—in other words, complete a cycle of inspecting PSO’s overhead distribution power lines and removing reliability-threatening vegetation every four years. The initial results we have seen indicate PSO is on the right path to significantly reduce outage frequency for our customers.
- In Tulsa, trees cause the greatest number of customer outage minutes (about 30% of all service disruptions). Equipment failure is the second largest cause (about 23% of all outages). Equipment failure results from many causes, including accumulated storm damage and exposure to the elements over decades.
- PSO does, indeed, have older infrastructure in the older areas of Tulsa, and that is why our program to improve reliability includes inspection and maintenance of the overhead distribution system, in addition to our Forestry operations.
After we complete the tree work along an electrical circuit, PSO construction crews traverse the circuit to inspect all of the equipment and replace any deteriorated hardware, including poles, cross-arms and insulators. While performing inspection and maintenance, we also install plastic guards to block animal access to the overhead distribution system, and install lightning protection equipment.
PSO’s comprehensive inspection and maintenance program is only made possible as a result of our tree trimming effort, as it provides us access to some parts of our overhead distribution system that have been inaccessible for many years due to the overgrown nature of the vegetation.
The equipment inspection and maintenance program works together with our Forestry operations to provide a significant boost in reliability for PSO’s customers.
- PSO recognizes that moving overhead power lines to underground is a way to improve reliability and reduce the need to trim and remove trees. In fact, PSO has identified about 700 miles of overhead lines across our system that we plan to convert to underground service. The targeted lines are heavily overgrown with trees, difficult to access for repair and maintenance and have histories of poor reliability. At present, we are well along with our first such conversion project, which is in Tulsa in the Regency Park West Addition. We are also planning another conversion project that may begin later this year. Please note, however, that PSO has more than 18,000 miles of overhead distribution power lines. We are not proposing to bury all of that. The cost of doing so would be enormous—far more than anyone would deem prudent.
PSO serves over one-half million customers—industries, businesses and homeowners—who depend on PSO for electric service. Our customers rightfully expect the power to be there when they flip a switch regardless of the wind and the weather, and for it to remain on for as long as they need it. PSO is working hard to keep the lights on for our customers.
