CPUC GO 95 Rule 35: the vegetation clearance rule, explained
Updated: Sep 21
Rule 35 of CPUC General Order 95 requires overhead supply and communication companies to maintain the minimum vegetation clearances set in Table 1, Cases 13 and 14, and to remove dead or diseased limbs overhanging a span once they have actual knowledge of them. Appendix E's larger time-of-trim clearances are guidelines, not the enforceable minimum.
Rule 35 is the vegetation rule in California's overhead line code, and it is shorter than almost anyone expects. Four paragraphs and four exceptions decide whether a trimmed span passes an audit or turns into a citation. Most of the confusion around it comes from one fact: the clearance a crew cuts to is not the clearance the rule enforces.
What Rule 35 actually requires
Rule 35 sits in Section III of General Order 95, "Requirements for All Lines." Its opening sentence carries the entire obligation:
Where overhead conductors traverse trees and vegetation, safety and reliability of service demand that certain vegetation management activities be performed in order to establish necessary and reasonable clearances the minimum clearances set forth in Table 1, Cases 13 and 14, measured between line conductors and vegetation under normal conditions, shall be maintained.
Two cases, and which one governs is a question about location before it is a question about voltage. Case 13 is the radial clearance of bare line conductors from tree branches or foliage. Case 14 is the radial clearance from vegetation in the High Fire-Threat District, which Table 1 footnote (hhh) defines by reference to GO 95 Rule 21.2-D.
The caption printed on Case 14 still reads "in Extreme and Very High Fire Threat Zones in Southern California," language that predates the statewide CPUC Fire-Threat Map adopted in Decision 17-12-024 on December 21, 2017. The footnote is what governs; the caption is a leftover. Footnote (jjj) then carves back out again: Case 14 does not reach plowed or cultivated orchards of fruit, nut or citrus trees, where Case 13 clearances apply instead.
Rule 35 also points to Appendix E, and that is where most misreadings start. Appendix E is headed "Clearance of Poles, Towers and Structures from Railroad Tracks" and then, under that heading, carries the vegetation table.
Its numbers are described in its own text as "recommended minimum clearances that should be established, at time of trimming, between the vegetation and the energized conductors and associated live parts where practicable." Should, not shall. Table 1 is what an inspector measures against. Appendix E is what a crew cuts to so that Table 1 still holds when the cycle comes around again.
The gap between them is large. A 12 kV span inside Tier 2 is trimmed to Appendix E's recommended 12 feet. It falls into nonconformance only if it later closes to less than the 48 inches Case 14 requires in Table 1's column E. Twelve feet is the target; four feet is the line. The full set of numbers, case by case and column by column, and why the two are worked as separate figures, each belong to their own page.
Who the rule binds
The rule answers this itself, in one sentence that gets skipped:
These requirements apply to all overhead electrical supply and communication facilities that are covered by this General Order, including facilities on lands owned and maintained by California state and local agencies.
Three things follow from it. Rule 35 is not an electric-only rule; communication facilities are in scope on their own terms, and GO 95 Rule 18A makes the corrective-action duty run to each company, "including utilities and CIPs."
Public ownership of the land underneath is not an exemption, so a distribution line crossing a county regional park carries the same clearance obligation as one crossing a subdivision. And the duty attaches to the facility, not to the parcel: the party the Commission cites is the company that owns or operates the conductor, whatever the landowner did or refused to do.
That last point is why Exception 2 exists at all, and why a shared pole raises a question the rule does not answer on its face. Rule 18B handles the adjacent case, requiring a company that finds a safety hazard on another company's facility during its own inspection to notify that company no later than 10 business days after discovery. The pole owner is normally allowed no more than five business days to pass the notice along when the owner of the offending equipment cannot be determined.
The measurement condition almost nobody quotes
Table 1 footnote (ddd) attaches to Cases 13 and 14 and to nothing else:
Clearances in this case shall be maintained for normal annual weather variations, rather than at 60 degrees, no wind.
The rest of Table 1 is measured at 60 degrees Fahrenheit and no wind, the benchmark GO 95 Rule 37 sets for the vertical and horizontal clearances. The vegetation cases are deliberately not measured that way.
The clearance has to survive the year's ordinary heat and its ordinary wind, which means the conductor's position at 105 degrees on an August afternoon, sagging and blowing toward the tree, is the position that counts. Rule 37 reinforces it from the other direction: the clearances specified in Cases 11, 12 and 13 "shall in no case be reduced below the tabular values because of temperatures and loading."
The practical consequence is that a span measured at 22 inches on a still March morning, outside the High Fire-Threat District, is not comfortably above the 18-inch Case 13 minimum. It is four inches of margin against a full summer of sag, sway and growth, and what exactly was measured, and from what, decides whether that four inches is real.
Contact is not automatically a nonconformance
The rule's third paragraph deals with secondary and service conductors, and it is the part most often quoted back incorrectly. Communication and electric supply circuits energized at 750 volts or less, including their service drops, "should be kept clear of vegetation in new construction and when circuits are reconstructed or repaired, whenever practicable." Once a company has actual knowledge that such a circuit "shows strain or evidences abrasion from vegetation contact," the condition shall be corrected, by one of four named remedies:
reducing conductor tension
rearranging or replacing the conductor
pruning the vegetation
placing mechanical protection on the conductors
Rule 35 then defines its own terms, which is rare in GO 95 and worth reading exactly:
For the purpose of this rule, abrasion is defined as damage to the insulation resulting from the friction between the vegetation and conductor. Scuffing or polishing of the insulation or covering is not considered abrasion. Strain on a conductor is present when vegetation contact significantly compromises the structural integrity of supply or communication facilities. Contact between vegetation and conductors, in and of itself, does not constitute a nonconformance with the rule.
So a photograph of a limb resting on a triplex service drop, showing a polished stripe on the jacket and no cut into it, does not on its own document a Rule 35 nonconformance. The record has to show damage to the insulation or a compromise of structural integrity. That language was added by Decision 12-01-032 on January 12, 2012, and it settled a dispute that had been costing both utilities and inspectors real time.
Dead, rotten and diseased, and the actual-knowledge trigger
The second paragraph is the overhang provision, and every word of its trigger matters. It reaches dead, rotten or diseased trees, and the dead, rotten or diseased portions of otherwise healthy trees. When a company "has actual knowledge, obtained either through normal operating practices or notification to the company," that those trees or portions "overhang or lean toward and may fall into a span," they "should be removed."
Two features distinguish this from the clearance obligation above it. It is not distance-based; a sound limb at 30 feet raises nothing under this paragraph, and a dead one leaning at 60 feet does. And the duty begins on knowledge, whether that knowledge arrived through a scheduled patrol or through a phone call from the property owner.
The date a condition was first seen is therefore the date the clock starts, which is why the inspection record does more work here than anywhere else in Rule 35. What qualifies the tree in the first place and what authority exists to take it down immediately are separate questions with separate answers.
The four exceptions, and what each one costs
Exception 1 covers conductors, or aerial cable complying with Rule 57.4-C, energized at less than 60,000 volts, where trimming or removal is not practicable and the conductor is separated from the tree by suitable materials or devices to avoid abrasion and grounding. Table 1 footnote (bbb) is the same relief seen from the table side. It is conditioned on impracticability, not on preference, and covered conductor alone does not invoke it.
Exception 2 is the good-faith exception, and it is specific about evidence. A good-faith effort "shall consist of current documentation of a minimum of an attempted personal contact and a written communication, including documentation of mailing or delivery." Two artifacts, both current, one of them proving delivery was attempted.
The written communication may include a statement that the company may seek to recover costs and liabilities arising from its inability to trim. And where permission is genuinely unobtainable and Exception 2 is met, the company is not compelled to fall back on Exception 1.
Exception 3 is not a safe harbor. It acknowledges that unusual circumstances beyond the utility's control can produce nonconformance, and then says the utility may be directed to take prompt remedial action "whether or not the nonconformance gives rise to penalties or is alleged to fall within permitted exceptions."
Exception 4, added by Decision 97-10-056 on October 22, 1997, exempts mature trees whose trunks and major limbs sit more than six inches, but less than the clearance required by Table 1 Cases 13E and 14E, from primary distribution conductors. Column E is Table 1's column for supply conductors and cables of 750 to 22,500 volts, so the ceiling on the exemption is 18 inches outside the High Fire-Threat District and 48 inches inside it.
The trunk or limb must be of sufficient strength and rigidity to keep from encroaching on that six-inch minimum "under reasonably foreseeable local wind and weather conditions." Then the rule states plainly who carries the risk: "The utility shall bear the risk of determining whether this exemption applies, and the Commission shall have final authority to determine whether the exemption applies in any specific instance." It is a judgment the company makes in the field and the Commission grades afterward, on the file.
What compliance looks like in the record
Rule 35 says what the clearance is. GO 95 Rule 18A says what the company must be able to show about it. Every company is required to run an auditable maintenance program, sort nonconformances into three priority levels, correct within the period set for the level, and keep the records.
The Level 2 clocks are where a Rule 35 finding usually lands, and they are set by location:
Level 2 nonconformance | Correction time |
Fire risk in Tier 3 of the High Fire-Threat District | Not to exceed six months |
Fire risk in Tier 2 | 12 months |
Worker safety compromised | 12 months |
All other Level 2 conditions | 59 months |
Rule 18A also names the circumstances that can extend a correction time, and the first one on the list is third-party refusal. Level 1 is immediate action. Level 3 is re-inspect, re-evaluate or repair as appropriate.
The record standard itself is one sentence in Rule 18A(1)(b). It says what the file must contain on completion of the corrective action:
the company's records shall show, with sufficient detail, the nature of the work, the date, and the identity of persons performing the work
Those records are preserved for at least ten years and produced to Commission staff on 30 days notice. That is the altitude a Rule 35 record is written at. Not "span cleared," but which span, on which date, by whom, to what measured clearance.
What that looks like as a working document and how long each piece of it has to survive are their own subjects. Rule 18A(3) then defers to the older machinery: a company already running a General Order 165 auditable inspection and maintenance program consistent with Rule 18A continues under that program.
Where Rule 35 stops
Rule 35 is the Commission's rule, and it is rarely the only clearance obligation on a given span. On State Responsibility Area land the same conductor also carries PRC 4293's radial clearances, enforced by CAL FIRE on a different theory and to different numbers. Above 200 kV, NERC FAC-003 applies on top of both. Which body enforces which of them is worth knowing before an audit, not during one.
On the CPUC side, the exposure is statutory. Public Utilities Code section 2107 sets a penalty of not less than $500 and not more than $100,000 for each offense, the ceiling raised by SB 901 (Stats. 2018, ch. 626, sec. 37).
Section 2108 makes each day of a continuing violation a separate and distinct offense. Since Decision 14-12-001, the Commission's electric safety citation program has let Safety and Enforcement Division staff issue citations for GO 95 violations directly, without opening a formal proceeding first, and Rule 35 is among the rules it names.
Further reading
Minimum vegetation clearance by voltage in California: The Table 1 numbers themselves, case by case and column by column.
Time-of-trim clearance versus maintained clearance: Why a crew cuts to one number and an inspector measures against another.
GO 95 Rule 35 and PRC 4293: two rules, two different clearances: The second clearance obligation that lands on the same span in an SRA.
Frequently asked questions
Does GO 95 Rule 35 apply to communication companies, or only to electric utilities?
Both. The rule states that its requirements apply to all overhead electrical supply and communication facilities covered by General Order 95. GO 95 Rule 18A carries the same reach, placing the corrective-action duty on each company, including utilities and communications infrastructure providers.
Is a tree touching a power line automatically a Rule 35 violation?
No. Rule 35 says that contact between vegetation and conductors, in and of itself, does not constitute a nonconformance. On circuits at 750 volts or less the trigger is strain or abrasion, and the rule defines abrasion as damage to the insulation from friction. Scuffing or polishing is expressly not abrasion.
Which Table 1 case applies to my span, Case 13 or Case 14?
Case 14 applies in the High Fire-Threat District, which Table 1 footnote (hhh) defines by reference to GO 95 Rule 21.2-D. Case 13 applies elsewhere, and also inside the district for plowed or cultivated orchards of fruit, nut or citrus trees under footnote (jjj).
Does a property owner's refusal to allow trimming excuse the utility?
Only if Exception 2 is satisfied. That requires current documentation of at least an attempted personal contact and a written communication, including documentation of mailing or delivery. Without both artifacts on file, the refusal is not an exception, it is an uncorrected nonconformance.
