Power Regulation

FERC May Tighten Tree Trimming Regs

By Todd H. Cunningham | ECT Staff Writer Published: November 7th, 2012

Noting that vegetation-related outages have been a root cause of many blackouts, the Federal Energy Regulatory Commission is proposing to approve a revised vegetation management standard.

Federal regulators are supporting their watchdog's proposal to tighten standards for tree trimming around transmission lines. (Photo By: Thinkstock)

Federal regulators are supporting their watchdog’s proposal to tighten standards for tree trimming around transmission lines. (Photo By: Thinkstock)

The North American Electric Reliability Corp.’s revised tree trimming standard would modify its current version in several ways. According to the commission’s proposed rule (Docket RM12-4), improvements would include expanded applicability. If the rule is adopted, NERC’s standard now would cover overhead transmission lines operated below 200 kilovolts—under certain specified circumstances—as well as all those operated at or above 200 kv.

The revised standard also would,  for the first time, require annual vegetation inspections, and incorporate new minimum clearance distances between vegetation and power lines.

But while FERC is proposing to approve the standard, the commission would direct NERC—consistent with activity the watchdog has already initiated—to conduct or arrange for testing to obtain data that either confirms these minimum distances, or provides reason to revisit them.

“No issue is more central to reliability than timely and effective tree trimming to keep the transmission system operational,” Commissioner Cheryl LaFleur commented prior to the panel’s vote on the rule. She termed NERC’s proposed standard “an important step forward in addressing this basic reliability issue.”

“Indeed,” she added, “a tree contact was a key contributing cause of the 2003 blackout that gave rise to this commission’s jurisdiction over reliability.”

Looking forward, LaFleur praised the commitment by NERC and the industry, in conjunction with the Electric Power Research Institute, to fund further research on the proposed minimum vegetation clearing distance.

According to Commissioner John Norris, the proposed standard was “about executing the fundamentals necessary to keep the lights on.” It “recognizes the inevitability of outages if vegetation management is not in a continual state of maintenance,” he noted.

The deadline for comment on FERC’s proposed rule is Dec. 24.  Patti Metro, NRECA manager, transmission and reliability standards, said the association will work with members to determine the impact of the proposal and decide whether to respond.

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