GO 95 vs PRC 4293: two clearance rules on the same span

GO 95 Rule 35 and PRC 4293 are separate obligations and neither excuses the other. PRC 4293 requires four feet at 2,400 to 72,000 volts, six feet to 110,000, and ten feet above, on brush or forest covered land in a State Responsibility Area. Table 1 Case 13 requires 18 inches at 12 kV, so the larger figure governs.

A 12 kV feeder crossing brush covered land in the Sierra foothills carries two vegetation clearance obligations at the same time, imposed by two bodies, on two theories, to two different numbers. Neither rule mentions the other. A crew can clear that span to a figure that closes out a Rule 35 nonconformance and leaves a live violation of the Public Resources Code behind it, and the paperwork will not say so unless somebody wrote it to.

Neither rule defers to the other

GO 95 draws its own boundary in Rule 12, Applicability of Rules: "These rules apply to all overhead electrical supply and communication facilities which come within the jurisdiction of this Commission, located outside of buildings, including facilities that belong to non-electric utilities."

Rule 12 has six subrules, covering construction, maintenance, lines built before the order, reconstruction, emergency installation and third party nonconformance. None of them says what happens when another body's standard is stricter, and neither Rule 35 nor any of its four exceptions refers to the Public Resources Code or to CAL FIRE.

PRC 4293 begins the same way, looking only inward: "Except as otherwise provided in Sections 4294 to 4296, inclusive." Those are three sections of the same code. The statute does not defer to the Commission, and the Title 14 regulations that operate it do not either.

There is exactly one place the two texts touch, and it is not a conflict rule. GO 95 Appendix E lists what a utility may weigh when it sets clearances beyond the guideline figures:

"line operating voltage, length of span, line sag, planned maintenance cycles, location of vegetation within the span, species type, experience with particular species, vegetation growth rate and characteristics, vegetation management standards and best practices, local climate, elevation, fire risk, and vegetation trimming requirements that are applicable to State Responsibility Area lands pursuant to Public Resource Code Sections 4102 and 4293."

A guideline, pointing at a statute, in a list of considerations.

So the operative clearance on a span reached by both is the larger of the two figures. Not because either rule says so, but because neither one discharges the other.

Each rule is bounded on a different axis

Rule 35's limit is jurisdictional and it has essentially no geography. It reaches the facilities the General Order covers, statewide, every day of the year, and it says in its own text that public ownership of the land underneath changes nothing.

PRC 4293 is the opposite shape. It has no jurisdictional limit at all, binding "any person that owns, controls, operates, or maintains any electrical transmission or distribution line," and it is then bounded three separate ways.

By land cover. The duty attaches "upon any mountainous land, or in forest-covered land, brush-covered land, or grass-covered land." A conductor over an irrigated pasture or a paved arterial is outside the statute on its face.

By a determination. The clearance is owed "during such times and in such areas as are determined to be necessary by the director or the agency which has primary responsibility for the fire protection of such areas." The Director has made that determination standing, in 14 CCR 1252, titled Areas Where PRC 4292-4296 Apply in State Responsibility Areas:

"The Director will apply PRC 4292-4296 in any mountainous land, forest covered land, brush covered land or grass covered land within State Responsibility Areas unless specifically exempted by 14 CCR 1255 and 1257."

That heading and text were filed October 24, 2005 and became operative November 23, 2005. Outside the State Responsibility Area the determination belongs to the local agency with primary fire protection responsibility, and 14 CCR 1252 does not make it for them.

By season. 14 CCR 1253, Time when PRC 4292-4296 Apply, is one sentence and it is the one most often missed: the minimum firebreak and clearance provisions "are applicable during the declared California Department of Forestry and Fire Protection fire season for a respective county.

The Director shall post the declaration on the official Department web site." Rule 35 has no season. A span read on a date outside its county's declared season sits inside one standard and outside the other, and the date on the form is the only thing that makes which one checkable.

There is a voltage floor as well, and it sits lower than most people expect. PRC 4296 reads in full: "Sections 4292 and 4293 do not apply if the transmission or distribution line voltage is 750 volts or less."

But PRC 4293's own bands start at 2,400 volts, so a 1,200 volt circuit is neither exempted by 4296 nor given a distance by 4293. Table 1 Case 14 gives that same circuit 48 inches, a figure footnote (iii) allows a company to take down to 18 below 2.4 kV. Between 750 and 2,400 volts the Commission has a number and the statute has none.

The numbers, on one conductor

Operating voltage	GO 95 Case 13	GO 95 Case 14	PRC 4293
12 kV	18 in	48 in	48 in
66 kV	18 in	48 in	48 in
100 kV	18 in	72 in	72 in
115 kV	19 in	120 in	120 in
230 kV	30.5 in	120 in	120 in
500 kV	115 in	120 in	120 in

How the Case 13 figures above 22.5 kV are produced, and which Table 1 column a given conductor sits in, belong to their own page. What the comparison shows is that the third column is the second column.

Case 14's 48 inches is PRC 4293(a)'s four feet. The 72 inches footnote (fff) sets between 72 and 110 kV is 4293(b)'s six feet. The 120 inches it sets above 110 kV is 4293(c)'s ten feet. The band edges match too, at 2,400 volts, at 72 kV and at 110 kV, which are not the edges Table 1 uses anywhere else. Case 14 is the statute, restated inside the Commission's table and made to apply on the High Fire-Threat District's boundary rather than the State Responsibility Area's.

The two columns separate in two places only. Above 500 kV, footnote (ggg) adds 0.40 inch per kV and the statute stays flat at ten feet. Below 2,400 volts, Case 14 has a figure and the statute does not.

Everything expensive is in the left column. On land that is brush covered State Responsibility Area but outside the High Fire-Threat District, Case 13 asks 18 inches of a 12 kV feeder and PRC 4293(a) asks 48. At 115 kV the same pair is 19 inches against 120. One span, one afternoon, one conductor, and a six-fold spread between the two answers, with the smaller of them coming from the Commission.

Appendix E's left column is the statute

Rule 35 points to Appendix E for time-of-trim guidance, and Appendix E prints two columns of recommended radial clearances, one headed Case 13 of Table 1 and the other Case 14 of Table 1. The Case 13 column reads 4 feet, 6 feet, 10 feet and 15 feet. The rows those run against begin "Radial clearances for any conductor of a line operating at 2,400 or more volts, but less than 72,000 volt," then 72,000 to 110,000, then 110,000 to 300,000, then 300,000 and above.

Those are PRC 4293's three distances, on PRC 4293's three voltage bands, in wording that tracks the statute's own phrasing. Appendix E adds one row the statute does not have, 15 feet above 300 kV, where PRC 4293 stops climbing at ten.

The practical consequence runs the wrong way from how it reads. Outside the High Fire-Threat District, on State Responsibility Area land, the figure a crew cuts to as a Commission guideline is the same figure CAL FIRE enforces as a statutory floor. Appendix E's own status is advisory, its clearances described as recommended and to be established where practicable, and the distinction between what a crew cuts to and what an inspector measures against is normally about margin.

Here it is not. Falling short of Appendix E on that span is falling short of PRC 4293. A willful or negligent failure to do what PRC 4293 requires is a misdemeanor under PRC 4021, which reaches the omission of acts required by Chapter 2 through Chapter 6 of Part 2 of Division 4. PRC 4293 sits in Chapter 3.

The measurement conditions are not interchangeable

Table 1 footnote (ddd) reaches Cases 13 and 14 and nothing else, replacing the still-air benchmark used everywhere else in the table with normal annual weather variations. That is the Commission's condition, and it is written as a range of ordinary conditions the clearance must survive.

PRC 4293 sets a fixed ceiling instead:

"In every case, such distance shall be sufficiently great to furnish the required clearance at any position of the wire, or conductor when the adjacent air temperature is 120 degrees Fahrenheit, or less."

14 CCR 1256, Minimum Clearance Provisions-PRC 4293, then adds the half that GO 95 leaves implicit. The distance is "measured at a right angle to the conductor axis at any location outward throughout an arc of 360 degrees."

It must hold at "any position through which the conductor may move, considering, among other things, the size and material of the conductor and its span length." It must hold as well at "any position through which the vegetation may sway, considering, among other things, the climatic conditions, including such things as foreseeable wind velocities and temperature, and location, height and species of the vegetation."

That second clause changes what a number means. A 51-inch reading taken in still air on a 400 foot span, with a flexible bay laurel standing on the downhill side, is not a 51-inch clearance under 1256. The sway is inside the measurement, not a cushion sitting outside it, and what was measured and from which surface has to say which convention was used. Two inspectors can walk the same span, both be honest, and file different numbers.

Covered conductor gets an answer from one rule only

Cases 13 and 14 are both titled for bare line conductors, and the only weight GO 95 gives a covering runs through Rule 35's Exception 1, which is conditioned on trimming or removal being impracticable rather than on the covering itself.

PRC 4293 starts from the other end. It requires clearance "between all vegetation and all conductors which are carrying electric current," with no bare qualifier at all, and then answers the covering question twice, explicitly.

PRC 4294: "A clearing to obtain line clearance is not required if self-supporting aerial cable is used. Forked trees, leaning trees, and any other growth which may fall across the line and break it shall, however, be removed." The second sentence survives the first, so the cable buys relief from the radial clearance and none from the overhang duty.

14 CCR 1257(a)(1) then exempts the minimum clearance provisions where conductors are:

• "insulated tree wire, maintained with the high density, abrasion resistant outer covering intact"

• "insulated self-supporting aerial cable, maintained with the insulation intact"

• "supported by sound and living tree trunks from which all dead or decadent branches have been removed"

Both of the first two conditions turn on the word intact, which is a thing an inspector can look at and photograph. 14 CCR 1258 closes the loop on the third. Where conductors are fastened to living, sound trees, "commonly referred to as tree lines, the requirements of PRC 4292 and 4293 shall apply the same as to a pole or tower line."

So a close photograph of the covering at the point of contact, showing the jacket unbroken, is the evidence that carries a 1257(a)(1) exemption. Under Rule 35 the same photograph carries nothing, because the covering is not what Exception 1 turns on.

Refusal is a different fact under each rule

Rule 35's Exception 2 is about conduct. It asks what the company did, and it wants two current artifacts, one of them proving delivery was attempted.

PRC 4295 asks a different question entirely:

"A person is not required by Section 4292 or 4293 to maintain any clearing on any land if such person does not have the legal right to maintain such clearing, nor do such sections require any person to enter upon or to damage property which is owned by any other person without the consent of the owner of the property."

That is a test of legal right and of consent, not of effort. Added by Stats. 1965, Ch. 1144, and unamended since.

Usually the same file answers both, because the letter and the attempted visit that satisfy Exception 2 are also what establishes that consent was withheld. But the file has to say the second thing and not only the first, and it has to name the parcel rather than the span.

CAL FIRE's stated expectation adds a step the Commission does not ask for. The Power Line Fire Prevention Field Guide, November 2008 edition, at page 14, says PRC 4295 "is not, however, intended as a loophole." Utilities are "expected to make reasonable effort to secure permission to make the clearances and, if unsuccessful, to report their problem to the responsible fire protection agency."

After that report, "the agency can then attempt to persuade the property owner to allow the clearing." The guide is not itself a regulation, except where 14 CCR 1257(b) incorporates named pages of it. A refusal file with no report to the fire agency is complete under Exception 2 and short of what the enforcing agency has said in print that it expects.

The same six inch tree, filed two ways

Rule 35's Exception 4 was added October 22, 1997 by Decision 97-10-056. It lifts the clearance requirement off a mature tree whose trunk and major limbs stand at least six inches from a primary distribution conductor but closer than Table 1 Cases 13E and 14E would otherwise require. The utility bears the risk of that call and the Commission grades it afterward. There is no register, no filing and no confirming professional.

14 CCR 1257(a)(3) does the same job for PRC 4293 and charges a very different price for it. The tree must clear six inches from the line at all times, measure at least six inches in diameter at conductor level, and carry no scaffold branches below eight and one half feet, all "as confirmed by a Certified Arborist or a Registered Professional Forester." Every utility with primary distribution conductors in a State Responsibility Area then owes three things.

• It must inspect its Exempt Trees annually.

• It must hold a database giving each one's location as latitude and longitude in decimal degrees on WGS84 along with species and last inspection date.

• It must report that database to CAL FIRE in an electronically researchable format by July 1 each year for the previous calendar year.

Where contact has happened or is anticipated, the condition is corrected by altering the tree or applying an engineering solution, and the action is documented in the same database. Subsection (b) then withholds the whole exemption from Hazard Trees, as identified on pages 1-20 through 1-24 of the November 2008 Field Guide.

One 14-inch valley oak standing 30 inches off a 12 kV phase inside a State Responsibility Area is therefore two things at once. Under Rule 35 it is a judgment a qualified person makes in the field and the company defends if the Commission ever asks. Under 14 CCR 1257 it is a coordinate, a species, an arborist's confirmation, an annual inspection date and a line in a July 1 filing. The tree has not moved. The file has.

Two findings, two units of measure

The Commission's side runs through GO 95 Rule 18A:

• an auditable maintenance program

• three priority levels

• correction intervals set by level and location

• records showing the nature of the work, the date and who did it, kept ten years

CAL FIRE's side is built differently and says so. The Field Guide, at page 21, instructs that "Because of the danger of electrocution, fire agency personnel are NOT to attempt to physically or mechanically measure conductor clearances. Visual estimation is adequate."

The finding is written on a California Fire Safety Inspection Report, form LE-38, and "a copy should be sent or given to the electric utility." The same guide, at page 63, is equally direct about the other direction: protection agency personnel should know GO 95, but "they have no responsibility for enforcing it," and their contribution is to observe infractions and report them to the utility.

So the two findings arrive in different units. One is a visual estimate from a party who is instructed not to measure, delivered on an agency form, on a statute whose breach is a misdemeanor. The other is a measured nonconformance inside the utility's own program, on a rule whose penalty exposure runs through Public Utilities Code sections 2107 and 2108. Which body can actually do what about each is worth settling before an audit rather than during one.

What the span record has to name

A clearance figure standing alone answers neither rule, because the same figure passes one and fails the other depending on facts the figure does not carry.

Take 22 inches at the closest approach on a 12 kV distribution span, west phase, measured on August 14, 2026, in a county whose fire season is declared, on brush covered land inside a State Responsibility Area but outside the High Fire-Threat District. Against Table 1 Case 13 that span conforms, with four inches to spare.

Against PRC 4293(a) it is 26 inches short of a statutory minimum. The reading is the same reading. What decides it is the land cover, the responsibility area, the fire-threat tier and the date, and a record that omits any one of those cannot be tested against both standards by anyone who was not standing there.

Four things, then, alongside the number: which land the span crosses, which date it was read, which Table 1 case was applied, and which subdivision of PRC 4293 was applied. Named that way, the entry survives an evaluator working from either direction. Named as a distance and a span number, it survives neither.

Further reading

• CPUC GO 95 Rule 35: the vegetation clearance rule, explained: The Commission's side of the pair, rule by rule and exception by exception.

• PRC 4293 radial clearance in State Responsibility Areas: The statute read on its own terms, with the Title 14 regulations that operate it.

• Which agency enforces which vegetation rule: CAL FIRE, the CPUC and NERC, and what each one can actually do about a finding.

Frequently asked questions

If a span meets GO 95 Rule 35, is it compliant with PRC 4293?

Not necessarily. Outside the High Fire-Threat District, GO 95 Table 1 Case 13 requires 18 inches at 12 kV while PRC 4293(a) requires four feet. On brush covered land inside a State Responsibility Area both apply, so a span held at 22 inches conforms to Case 13 and falls 26 inches short of the statute. Neither rule contains a provision deferring to the other.

Does PRC 4293 apply all year?

No. 14 CCR 1253 makes the minimum firebreak and clearance provisions of PRC 4292 through 4296 applicable during the declared CAL FIRE fire season for the respective county, and requires the Director to post the declaration on the Department's website. GO 95 Rule 35 carries no seasonal limit at all, which is why the date on an inspection form decides which of the two standards was live when the reading was taken.

Do the GO 95 and PRC 4293 numbers ever agree?

Inside the High Fire-Threat District they are the same numbers. Table 1 Case 14 requires 48 inches to 72 kV, 72 inches to 110 kV and 120 inches above that, which are PRC 4293's four, six and ten feet on PRC 4293's own voltage bands. They part above 500 kV, where footnote (ggg) adds 0.40 inch per kV and the statute does not, and below 2,400 volts, where Case 14 sets a figure and the statute sets none.

Does covered conductor change the answer under either rule?

Under PRC 4293 it can. 14 CCR 1257(a)(1) exempts insulated tree wire kept with its abrasion resistant covering intact and insulated self-supporting aerial cable kept with its insulation intact, and PRC 4294 says a clearing is not required where self-supporting aerial cable is used, while still requiring removal of growth that may fall across the line. GO 95 Cases 13 and 14 are written for bare line conductors and Rule 35's Exception 1 turns on whether trimming is practicable rather than on the covering.