Circle of Safety, Reliability and Regulations Impact

Circle of Safety, Reliability and Regulations Impact


By William Porter, Director of Consulting Services, CN Utility Consulting

This article was originally published in the March/April 2013 issue of Utility Arborist Newsline.

Utility vegetation management (UVM) surveys indicate that the primary objectives of UVM are safety and electric reliability. These objectives are essential characteristics of a green industry that is still trying to define its role and scope of responsibility in society. How UVM evolves will depend on how those objectives are prioritized among others.

For UVM to be successful, UVM program planners should understand the relationship between reliability and the elements that make up a UVM program and how safety and electric reliability are regulated rights and commodities.

Electric reliability is driving the UVM regulations being crafted and adopted in many states. These new rules are attempting to guarantee reliable service to citizens who have come to expect uninterrupted power delivery. Investor Owned Utilities (IOUs), which exist under the regulatory oversight of public utility commissions (PUCs), are the primary entities impacted by these rules, with many cooperatives still self-regulating (Cooper 2008). However, these new regulations are impacting the way UVM is being performed even outside the utilities they regulate (CNUC 2010). They are influencing UVM standards of care, and any arboricultural standard of care has to begin with safety.

Electric cooperatives provide a unique opportunity to examine the relationships among safety, reliability and regulations.

Electric Cooperative Regulations

Cooperatives are regulated by their member-elected board of directors (Cooper 2008). In some states, the PUC regulates cooperatives. However, seldom are there commissionenforced rules that pertain to REC UVM.

Some state PUCs have the authority to enforce the same rules that apply to IOUs. For example, in South Carolina, all utilities, including cooperatives, must comply with commission rules (Title 58-27-40. t58c027.php). In the case of Iowa, the Iowa Utility Board not only has jurisdiction over cooperatives, it has specific rules that regulate reliability and UVM activities (Rule 19920.18 (476,478 https://www.legis.iowa. gov/DOCS/ACO/IAC/LINC/11-14- 2012.Rule.199.20.18.pdf). However, in Florida the exercise of commission authority is limited to a few areas of the REC business activities ( utility/puc_study_march2011.pdf).

What Do Regulations Mean for electric Cooperatives?

Considering that almost half of the U.S. distribution line miles are owned by RECs, it is inevitable that RECs will be influenced by stateadopted UVM and reliability regulations. Although there are states in which the PUCs have regulatory oversight over RECs, there are a large number of PUCs that do not get involved with UVM. RECs in general are self-regulated when it comes to vegetation management (Cooper 2008). Many cooperatives indicate they adhere to the National Electrical Safety Code (NESC) 218 and A300, and they have sophisticated UVM programs that are administered much like the larger IOUs. However, the number of states that have detailed UVM requirements is increasing, and more UVM activities, such as storm resiliency and tree risk assessment are falling under PUC purview (CNUC 2010). Many cooperatives have responded by updating their UVM programs, even if they are not directly impacted by the regulations.

Since many cooperatives have grown in wealth and numbers of customers and some service territories are no longer primarily rural, there is a greater chance that public opinion will have an impact on UVM activities that involve electric reliability or safety. News about prolonged electric interruptions, wildfires and electrical accidents is now reaching geographically isolated customers through the Internet. Increased cooperative membership awareness of reliability and safety issues could influence the PUCs decision-making concerning UVM.

In the current regulatory environment, cooperatives have an opportunity to influence UVM policymaking rather than following the regulatory responses of IOUs.

A Cooperative Case Study: Are Reliability Indices Effective Tools to Measure UVM Efficacy?

Much of what we have learned about UVM has been tested in small-scale pilot projects. In fact, cooperatives already have a wealth of experience with which to understand the issues of reliability and safety, and they are excellent laboratories for proof of concept.

One of the utilities included in the CN Utility Consulting benchmark project (CNUC 2012) provides a good case study of a cooperative that is adapting its UVM program to fit a growing customer base and a changing culture of reliability expectations. The company is a medium-sized cooperative, with:

• 125,000 customers

• 152 customers per square mile

• 52 customers per line mile

• 1,000 square miles of service territory

• 30 percent urban/suburban

• 69 percent rural

• 1 percent remote

This cooperative has a five-year planned UVM cycle that is frequently a seven-year actual UVM cycle for urban/suburban and a 10-year actual cycle for rural. Once a circuit has a sufficient number of customers, it is deemed a suburban circuit and it is evaluated for an upgrade to a fiveyear cycle. The vegetation manager knows the 10-year cycle is much higher than industry standards. However, upper management has Page 18 Utility Arborist Newsline established that electric reliability standard indices will determine whether funds should be allocated to lower the cycle length. The coop’s tree-related, non-major event System Average Interruption Duration Index (SAIDI) is one of the industry’s lowest and, for the past three years, funds have been withheld for revising the UVM program for the 70 percent of their line miles that are still on a 10-year cycle. The System Average Interruption Frequency Index (SAIFI) is also comparatively better than a majority of utilities.

The question here is not whether five, seven or 10 years is too long to wait to perform UVM, but why reliability indices aren’t impacted by deviations from industry and best management practices for UVM. Is there a disconnect between reliability metrics and UVM efficacy? Is the answer to keep going with the current program and adjust when the SAIDI/SAIFI start to get worse? These are not only reliability questions. They are also safety, cost-effectiveness, customer service and fire risk questions that must be understood in the context of reliability and UVM program effectiveness.

The complexities of UVM and of electric delivery are different enough to necessitate different performance standards. The effects of UVM on reliability have to be understood, because electric interruptions are becoming unacceptable to end users under most circumstances. UVM has to be adequate, and if it isn’t, our experience is telling us that regulators will step in to ensure it is.

Why Would This Co-op be Concerned If Reliability Is not an Issue?

The data spans four years, enough time for roughly 40 percent of the rural lines to be managed one time. In one year (2009 to 2010), the number of non-major event treerelated outages jumped 28 percent. Should the UVM program address the circuits where these outages occurred or address the entire program, because in all likelihood a similar spike will happen again? Greater datasets and GIS information on outage locations would further explain the dichotomy of low SAIDI/ SAIFI and under-resourced rural UVM.

A more direct impact on the UVM program can be detected through time studies of reactive work. Figure 2 (below) shows how long-cycle rural UVM can precipitate increased reactive work at the expense of routine maintenance. The increased reactive work correlates directly with the increase in non-major event outages. Consequently, the already limited routine schedule is further constrained because resources are re-assigned to reactive work. Reductions in routine work caused by repeated spikes in outages, and reactive work over a 10-year cycle may only be marginally detectable in reliability metrics if the majority of the outages are in low customer density, rural areas.


While the cost of deferred maintenance is well documented, the relationship between reliability and UVM efficacy is not well established. More importantly, the relationships between public safety, worker safety and reliability metrics have not been investigated. It is important to remember that SAIDI and SAIFI are influenced by customer density. When electric reliability is measured over variable customer densities, outages in high density population regions will have more weight than in low density areas. This effect could hide problems with UVM efficacy.

The Circle of Safety, Reliability and Regulations

Although SAIDI and SAIFI for the case study cooperative were well within the acceptable industry benchmarks, it is obvious that the UVM program is not sustainable in its current form. It would be safe to predict that given the current conditions, the system will sustain many future episodes where the number of outages caused by trees will spike.

UVM has to be proactively planned from the perspective of UVM, not reactively planned from the perspective of electric reliability. Studies have shown that the cost savings for deferring maintenance, whether it is according to reliability indices or not, will result in much higher expenditures. The true cost of deferring maintenance may be the next wildfire, the next electrocution accident, the next hurricane or the next major storm.

Literature Cited:

CNUC (2010) Utility Vegetation Management Benchmark & Industry Intelligence

CNUC (2012) Distribution Preliminary Report 2011 – 2012 2nd Edition Cooper, J. (2008) Electric Co-operatives: From New Deal to Bad Deal? Harvard Journal of Legislation 45: 335-375.

Cooper, J. (2008) Electric Co-operatives: From New Deal to Bad Deal? Harvard Journal of Legislation 45: 335-375.

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