Utility vegetation management: what regulators say about cycles and programmes

This page reports what the official source says. It is not legal advice: ask the office named here. It covers the programme side of line clearance: how often lines are inspected, what a plan has to hold and who checks it. The worker side is on the line clearance work guide, and distances for people are in the approach distances table.

Time-based and risk-based, as the documents use the words

No regulator page read for this guide sets one pruning interval for all lines. The documents ask for something different: an inspection frequency, a written plan, and a clearance that has to hold between visits. The NSW guide defines a hazard management cycle as the time between return visits to cut vegetation, chosen so the minimum clearance holds without trimming "beyond that which is acceptable to the community". The NERC standard names its own three requirement types as performance-based, risk-based and competency-based.

United States and Canada

NERC FAC-003-5, transmission lines

FAC-003-5 is the NERC standard titled Transmission Vegetation Management. Its stated purpose is a defense-in-depth strategy to manage vegetation on transmission rights of way and to limit vegetation outages that could lead to cascading. The version history on the NERC PDF records a FERC order approving FAC-003-5 on March 4, 2022, in docket RD22-2-000. The federal rule at 18 CFR 40.3 tells the Electric Reliability Organization to post the effective Reliability Standards approved and enforceable by the Commission, with their effective dates.

The standard applies to overhead transmission lines operated at 200 kV or higher, and to listed lines below 200 kV. It says it is not intended to prevent customer outages from tree contact with lower voltage distribution lines. What it requires of the line owner:

R1: manage vegetation to prevent encroachment into the Minimum Vegetation Clearance Distance, which Table 2 of the standard sets by voltage.
R3: have documented maintenance strategies, procedures or specifications that account for conductor movement and for the link between vegetation growth rates, control methods and inspection frequency.
R4: tell the control center holding switching authority, without intentional delay, when a vegetation condition likely to cause a fault at any moment is confirmed.
R5: take corrective action where a constraint such as a landowner or court order blocks the work.
R6: inspect 100 percent of applicable lines at least once per calendar year, with no more than 18 calendar months between inspections of the same right of way.
R7: complete 100 percent of the annual vegetation work plan. The standard lists reasons the plan may be modified, among them growth rate, weather, permitting delays and crew or contractor availability.

The standard is published as FAC-003-5 on the NERC site and the federal rule as 18 CFR 40.3 on the eCFR.

Oregon

The Oregon Public Utility Commission fact sheet on its role in vegetation management says all Oregon electric utilities must follow its vegetation rules. It says the commission evaluates the programmes of investor-owned electric utilities every year, and inspects consumer-owned utilities at least every three years as part of National Electrical Safety Code reviews. It states that Oregon and California are the only states with specific minimum vegetation clearance requirements, and that Oregon is the only known state where commission staff audit programmes instead of only answering complaints. It adds that the rules do not address dead or hazardous trees outside the utility right of way, and that the commission does not set a utility's annual vegetation budget. See the Oregon PUC fact sheet.

California

General Order 95, Rule 35, says that where overhead conductors pass through trees, the clearances in Table 1, Cases 13 and 14, measured between conductors and vegetation under normal conditions, are to be maintained. It adds that dead, rotten or diseased trees that overhang or lean toward a span, once the company has actual knowledge, should be removed. Appendix E gives recommended radial clearances at the time of trimming and lists factors a utility may weigh beyond them, including planned maintenance cycles, growth rate and fire risk. For lines at 2,400 volts or more but under 72,000 volts it lists 4 feet for Case 13 and 12 feet for Case 14. See Rule 35 on the CPUC site and Appendix E. Filed wildfire plans are on the wildfire plans and tree clearing page.

Manitoba

Manitoba Hydro, a utility and not a regulator, describes its own programme as mechanical brush clearing along rights of way, with selective herbicides applied at least one year after clearing once new growth has started. Its page also links planned work for the fiscal year. See Manitoba Hydro on vegetation management.

United Kingdom

HSE's tree work page treats the line owner, usually the Network Operator, as the party that sets the safe system of work near overhead lines. It says a risk-based approach is needed for work within 10 m of overhead power lines, measured horizontally at ground level from below the nearest wire. It says the Network Operator may switch the power off, refine safety distances, or arrange for a specialised utility arboricultural contractor. See HSE on working near power lines.

Australia

Victoria

Energy Safe Victoria says its line clearance assurance team evaluates the electric line clearance management plans prepared by major electricity companies, municipal councils and other organisations with responsibilities, and audits compliance with the Electricity Safety (Electric Line Clearance) Regulations 2026. The Victorian legislation site lists those regulations as statutory rule 71/2026, in force from June 24, 2026. ESV says the regulations include a Code of Practice and prescribe management procedures to limit the danger of electric lines causing fire or electrocution. See ESV on legislation, policies and areas and the regulations on the Victorian legislation site.

New South Wales

The ISSC3 Guide for the Management of Vegetation in the Vicinity of Electricity Assets, issued November 2016, says a Network Operator is to run a system for routine inspection, identification and remediation of vegetation hazards, with cycles set by vegetation growth and local conditions. Its Table 1 sets minimum vegetation clearances by voltage, conductor type and span length, and adds 0.5 m for bare conductors in bushfire prone areas. See the ISSC3 guide.

New Zealand

A lines company page, Orion's, describes the Electricity (Hazards from Trees) Regulations 2003 as amended in October 2024 and July 2026. It lists a growth limit zone, a cut back zone one metre beyond it and a hazard warning notice zone two metres beyond the growth limit zone, a clear-to-the-sky requirement from October 17, 2026, and a treefall hazard zone from July 23, 2028 in which line owners are to assess trees within 24 m either side. Cut or trim notices give the tree owner 45 days. See Orion on trees near power lines.

At a glance

Body	What it sets	Inspection or cycle wording
NERC FAC-003-5	Clearance by voltage, written strategies, annual work plan	Every applicable line once per calendar year, no more than 18 calendar months apart
Oregon PUC	Minimum clearances in its rules, programme audits	Investor-owned programmes evaluated every year; consumer-owned inspected at least every three years
California PUC	Rule 35 clearances, Appendix E guidelines	Planned maintenance cycles named as a factor, no fixed interval in the pages read
HSE	Risk-based approach within 10 m	No interval; Network Operator sets the system of work
Energy Safe Victoria	Management plans under the 2026 regulations	Plans evaluated and audited; interval not stated on the pages read
NSW ISSC3	Clearance Table 1, hazard management cycle	Set by the Network Operator from growth and conditions
New Zealand regulations, as Orion describes them	Growth limit zone, notices, clear to the sky	45 days to cut after a notice