Table 1 of 8 CCR 2950: the minimum approach distance, and who owes it
Updated: Sep 21
Title 8 section 2950 applies Article 38 wherever a worker, a tool, or the tree itself is likely to come within Table 1's distance of an energized overhead conductor. Table 1 binds everyone who is not a qualified line clearance tree trimmer or trainee: 10 feet through 50 kV, rising to 35 feet at 800 kV.
Two ground workers on the same contract, one feeding a chipper under a 12 kV distribution feeder and one under a 115 kV subtransmission line. Neither is a qualified line clearance tree trimmer. Both have been told the 10 foot rule, and Cal/OSHA's own Tree Work Safety Guide prints it that way at page 5.
Only one of them has been given the right number. Table 1 of Title 8 section 2950 owes the first worker 10 feet and the second 12 feet 4 inches, and the same table decides, before anyone puts a hand on a tree, whether the job is line clearance tree trimming at all.
What section 2950 does, and what Article 38 contains
Article 38 of the High-Voltage Electrical Safety Orders, formerly Article 87 and renumbered by an editorial correction filed November 2, 1983, has exactly two sections. Section 2951 carries the operating rules. Section 2950 is titled Application, and it does two jobs in five lines.
The first is the switch. Subsection (a):
This article shall apply to all line clearance tree trimming operations performed in the vicinity of exposed energized overhead conductors and equipment where any part of the employee's body, tools or equipment being used, or parts of trees being worked upon, is likely to come within the distances specified in Table 1 of this section.
Three things are inside that trigger and all three are commonly left out of a job brief. The employee's body is the obvious one. Tools or equipment being used takes in the pole pruner, the pole saw, the rope, and the aerial device.
Parts of trees being worked upon is the one that decides most jobs: a limb that will swing, drop or be lowered through the space near the conductor puts the operation inside Article 38 even if the climber never gets close. The test is likely to come within, not did come within, so it is answered when the work is planned rather than after it.
The second job is the distance itself. Subsection (b):
Minimum approach distances to energized conductors for persons other than qualified line clearance tree trimmers and trainees shall be maintained in accordance with Table 1.
Note what that produces. The same figure runs the scope of the whole article and the limit for the unqualified people standing under it. On a 115 kV line the trigger is 12 feet 4 inches. Work planned to bring a limb 11 feet from that conductor is line clearance tree trimming in California. The ground crew who are not qualified trimmers are already outside their own limit at that distance.
Subsection (b) and Table 1 are not original to the section. They were adopted by an amendment filed September 25, 2012, operative October 25, 2012, at Register 2012, No. 39, and the General Industry Safety Orders sections 3420 and 3423 were amended in the same register entry. Before that date Article 38 named no distance of its own at all.
Table 1, and the arithmetic it was built from
The table as printed, in the regulation's own three columns:
Nominal voltage, phase to phase (kV) | Distance (ft in) | Meters |
0.0 to 1.0 | 10 00 | 3.05 |
1.1 to 15.0 | 10 00 | 3.05 |
15.1 to 36.0 | 10 00 | 3.05 |
36.1 to 50.0 | 10 00 | 3.05 |
50.1 to 72.5 | 10 09 | 3.28 |
72.6 to 121.0 | 12 04 | 3.76 |
138.0 to 145.0 | 13 02 | 4.00 |
161.0 to 169.0 | 14 00 | 4.24 |
230.0 to 242.0 | 16 05 | 4.97 |
345.0 to 362.0 | 20 05 | 6.17 |
500.0 to 550.0 | 26 08 | 8.05 |
785.0 to 800.0 | 35 00 | 10.55 |
Four features of it change how a crew uses it.
The first four rows are the same number. From 0.0 kV to 50.0 kV the distance is 10 feet and it does not move. A 480 volt service drop, a 4 kV lateral, a 12 kV feeder and a 21 kV circuit are one row as far as an unqualified person is concerned.
The table's first step is at 50.1 kV. Anyone reading the table as a ladder that descends with voltage will get the lower half of the system wrong, and the lower half of the system is where most distribution clearing happens.
The rows are nominal transmission classes, not a continuous scale. There is no row between 121.0 and 138.0 kV, none between 145.0 and 161.0, none between 169.0 and 230.0, none between 242.0 and 345.0, none between 362.0 and 500.0, and none between 550.0 and 785.0. The gaps fall between standard classes rather than inside them, so a 60 kV, 115 kV, 138 kV, 161 kV, 230 kV or 500 kV circuit all land on a printed row.
Where something does fall in a gap, section 2951(a) supplies the exit: the employer may determine the maximum nominal voltage to which an employee will be exposed and treat all lines as energized at that voltage, which lands the crew on the next row up.
The distances are arithmetic, and the formula is in a different article. Section 3420(b) of the General Industry Safety Orders defines Proximity as an area within 10 feet of conductors rated 50 kV phase to phase or less, increasing by 4/10 inch for each additional kilovolt above that.
Run that formula at the highest voltage in each Table 1 band and every row falls out: 22.5 kV over 50 gives 9 inches, and the 50.1 to 72.5 row reads 10 feet 9 inches. Ninety-five kilovolts over 50 gives 38 inches, and the 138.0 to 145.0 row reads 13 feet 2 inches.
Five hundred kilovolts over 50 gives 200 inches, and the 500.0 to 550.0 row reads 26 feet 8 inches exactly. Seven hundred and fifty over 50 gives 300 inches, and the last row reads 35 feet.
Of the eight rows above 50 kV, four are exact, three are rounded up by two tenths or four tenths of an inch, and one, the 72.6 to 121.0 row, is rounded down by four tenths. That is worth knowing for one practical reason: the number a crew owes is the number for the top of its band, not the number for the voltage on the tag.
The two distance columns are not conversions of each other. They are the same rule computed in different units, 4/10 inch per kilovolt against 10 millimeters per kilovolt, and 4/10 inch is 10.16 millimeters. The gap compounds. At 550 kV the imperial column gives 26 feet 8 inches and the metric column gives 8.05 meters, which is 26 feet 5 inches.
At 800 kV the imperial column gives 35 feet and the metric column gives 10.55 meters, which is 34 feet 7 inches. A crew working a 500 kV corridor from a metric rangefinder is three inches inside the figure the same table prints in feet. On transmission, take the larger of the two.
Who Table 1 binds, and who it lets go
Subsection (b) draws its line by exclusion: everyone except qualified line clearance tree trimmers and trainees. Inside a line clearance operation that is a longer list than it first looks.
The ground crew are on it. So are these:
The chipper operator.
The flagger holding traffic on a roadside span.
The foreman who is qualified as a supervisor but not as a trimmer.
The utility inspector walking the job.
The biologist doing a nest survey ahead of the saw.
The general arborist a customer sends out to watch their tree come down.
None of them is inside the exclusion, and every one of them owes 10 feet on a 12 kV feeder.
The exclusion turns on two defined terms in section 2700, and only one of them requires a stated period of time. A Qualified Line Clearance Tree Trimmer is a person who has completed a minimum of 18 months related training and on the job experience and is familiar with the special techniques and hazards involved.
A Qualified Line Clearance Tree Trimmer Trainee is any worker regularly assigned to a line clearance crew and undergoing on the job training who has demonstrated the ability to perform the assigned duties safely at that level of training, with no period attached at all. What separates those two credentials from a qualified tree worker, and what a trainee's supervision has to look like to hold, are their own subjects.
Two consequences follow that are easy to state and easy to get wrong on a job site. A trainee is outside Table 1, which means a first-week trainee under direct supervision may lawfully be closer to a 12 kV conductor than a twenty-year general arborist standing on the ground next to them.
And qualification is a property of a person, not of a company: a contractor whose crew leads are qualified does not thereby put its ground personnel inside the exclusion. What the paperwork behind an individual's qualification has to show is where an evaluator will actually test this.
The three exceptions, and what each one costs to claim
Section 2950 prints three exceptions to subsection (b), and none of them is a status a person holds by job title alone.
Exception No. 1 is the only one that covers routine work.
A qualified tree worker as defined in the General Industry Safety Orders (GISO), Section 3420(b) may perform tree trimming activities within 10 feet, but no closer than 1 foot, of energized low voltage (600 volts or less) power lines and conductors, provided the provisions in GISO Section 3423 related to such work are met.
Three limits, all of them hard. The conductor must be at 600 volts or less, which on a distribution system means secondary and service, not the primary above it. The 1 foot floor is absolute: the exception opens a band between 10 feet and 1 foot and closes it there, so a qualified tree worker may never be nearer than 12 inches to an energized 120/240 volt service drop. And the conditions are the four competencies in section 3423(b)(2):
Distinguishing exposed live parts from other parts of electric equipment.
Telling low voltage from high voltage.
Knowing the minimum approach distances corresponding to the voltages the employee will be exposed to.
The work practices and protective equipment needed to avoid contact.
Cal/OSHA's Tree Work Safety Guide reprints this note beneath its copy of Table 1 at page 19 and cites 3423(b)(2) specifically, where the regulation itself cites section 3423 as a whole.
Above 600 volts there is no counterpart. Section 3423(c) closes the door from the other side, requiring line clearance tree trimming operations as defined in section 2700 to be conducted under Article 38 and permitting only qualified line clearance tree trimmers or trainees to perform them. How Article 12 handles the rest of tree work is a separate page; the part that matters here is that it does not open a second route to a primary conductor.
Exceptions No. 2 and No. 3 are emergency provisions and read almost identically. Number 2 covers a qualified telecommunication worker as defined in section 8601 of the Telecommunication Safety Orders. Number 3 covers a qualified electrical worker as defined in section 2700. Each is available only when the employee is "performing restoration work or other emergency work," and each is conditioned on the employee being "trained and experienced in the special techniques and work procedures required to avoid the hazards of line clearance tree trimming operations."
That condition is the whole exception. A qualified electrical worker is qualified in high voltage work by two years of training and experience with high-voltage circuits and equipment, which is not the same body of knowledge as felling and rigging next to a conductor. The exception does not transfer one qualification to the other; it asks whether this individual holds both, and it asks it in a context where nobody has time to check.
The document that answers it has to exist before the storm. A lineman who clears a limb off a conductor during a restoration is inside Exception No. 3 only if the employer can show the training that puts them there. A lineman who clears a limb during a scheduled outage is not inside it at all, because a planned outage is neither restoration work nor emergency work.
Where a qualified trimmer's own number comes from
Note 1 under Table 1 is a redirect, and it is the part of section 2950 most often read as though it were a blank:
Minimum approach distances to energized conductors for qualified line clearance tree trimmers and trainees as defined in Section 2700 are provided in the provisions and references of Section 2951 of these Orders.
Follow it and section 2951(b) hands the question on again: "Under no circumstances shall the minimum approach distances specified in Section 2940.2, be violated." So the trimmer's distance is not printed anywhere in Article 38. It comes from section 2940.2, which is not a lookup table but a choice of three methods the employer has to make and record. The employer may compute distances from the equations in Table 2940.2-1 for AC systems using a maximum anticipated per unit transient overvoltage determined by an engineering analysis.
Or it may take the published distances in Tables 2940.2-3 and 2940.2-4 and the last row of Table 2940.2-6. A third route, the older values in Appendix A, was available only until October 1, 2018 and has expired. For voltages over 72.5 kV the engineering analysis is not optional: subsection (a)(1)(A) required it by that same date, and the employer has to make it available to employees and to the Chief of the Division or designee for examination and copying.
Two provisions attached to that choice reach a California tree crew directly. Distances taken from the published tables must be multiplied by an altitude correction factor for work above 3,000 feet, which is most of the Sierra foothills and much of the higher elevation corridor work in the state. And section 2940.2(b) is a prohibition, not a target.
No employee may approach or take any conductive object without an approved insulating handle closer than the established distance unless the employee is insulated or guarded from the energized part, or the part is insulated or guarded from the employee. What section 2951 requires once the operation is underway covers the rest.
The practical upshot is that "what is the minimum approach distance for a qualified line clearance tree trimmer in California" has no single published answer. It has an employer's answer, arrived at by a named method, corrected for elevation, and written down. An evaluator asking a contractor which of the three methods in 2940.2(a) its distances came from is asking a question the contractor should be able to answer in one sentence.
The federal distance is not this distance
Table 1 carries an asterisk on its voltage heading and a single footnote: "Exceeds phase to ground minimum approach distances per the federal standard, 29 CFR 1910.333." That sentence is doing more work than its length suggests, and it explains the whole shape of the table.
29 CFR 1910.333(c)(3)(i)(A) gives an unqualified person 10 feet for voltages to ground of 50 kV or below, and 10 feet plus 4 inches for every 10 kV over 50 kV above that. The federal definition of line-clearance tree trimming uses the same two bands to fix its own scope.
Both are indexed to voltage to ground. Table 1 is indexed to nominal voltage phase to phase, and on a three phase system the phase to ground value is the phase to phase value divided by the square root of three. That single difference is why California's numbers are larger everywhere above 50 kV.
Work it on three California circuits. A 115 kV line is 66.4 kV to ground, so the federal figure is about 10 feet 7 inches and Table 1 says 12 feet 4 inches. A 230 kV line is 132.8 kV to ground, so the federal figure is about 12 feet 9 inches and Table 1 says 16 feet 5 inches.
A 500 kV line is 288.7 kV to ground, so the federal figure is about 17 feet 11 inches and Table 1 says 26 feet 8 inches. At 12 kV both regimes say 10 feet and the question never arises, which is exactly why it goes unnoticed until a crew moves to transmission.
One more asymmetry sits behind the two definitions. Federal 1910.269 builds a distance into the definition of the work itself, so whether a job is line-clearance tree trimming is answered by measuring. California's section 2700 definition of Line Clearance Tree Trimming Operations names no distance at all, describing the work as within the vicinity of electric supply lines and equipment, and leaves section 2950(a) to supply the measurement.
The two arrive at similar places by opposite routes, and they do not arrive at the same number. How the federal standard sorts unqualified employees, qualified employees and line-clearance tree trimmers, and what an arborist doing incidental work near a line may not assume, are the two pages that carry that further.
What the crew's record has to name
A section 2950 finding is closed by three entries, and the first of them is not a distance.
The voltage determination comes first, because Table 1 cannot be read without it and section 2951(a) requires it before work begins. The entry names the nominal voltage of the lines posing a hazard, or the maximum nominal voltage the employer has elected to treat every line as carrying, and it names which of those two it is. A record that says 12 kV without saying whether that was measured, taken from the utility's circuit map, or adopted as a maximum leaves the Table 1 row unproven.
The Table 1 row comes second, written as a row and not as a habit. Nominal 115 kV, row 72.6 to 121.0, 12 feet 4 inches, imperial column. Anyone who later asks why a crew stood where it stood can check that against the printed table in one step, which is not true of a file that records only "MAD maintained."
The qualification status of each person on site comes third, and it is the entry that decides which of the two regimes the other two entries belong to. For every worker: qualified line clearance tree trimmer, trainee, or neither. Where an exception is being relied on, the file holds the artifact rather than the label, because each of the three exceptions is a factual claim about a named person. Exception No.
1 needs the qualified tree worker determination under section 3420(b) and the 3423(b)(2) competencies, plus the evidence that the conductor was at 600 volts or less. Exceptions No. 2 and No. 3 need the restoration or emergency condition and the specific line clearance training the exception's own words require. An exception claimed without its artifact reads to an evaluator the way it reads to Cal/OSHA, which is as an unqualified person inside the minimum approach distance.
Further reading
Qualified line clearance tree trimmer versus qualified tree worker: The two Title 8 credentials that decide which side of Table 1 a person stands on.
8 CCR 2951: what a line clearance operation has to do: The operating rules that attach once section 2950 says the article applies.
GISO Article 12: tree work, maintenance and removal: The general industry article that section 2950's first exception is written against.
Frequently asked questions
What is the minimum approach distance for a 12 kV line under 8 CCR 2950?
Ten feet. Table 1 of section 2950 prints 10 feet and 0 inches for every nominal voltage from 0.0 to 1.0 kV up through 36.1 to 50.0 kV, so a 4 kV lateral, a 12 kV feeder and a 21 kV circuit all carry the same figure for a person who is not a qualified line clearance tree trimmer or trainee. The number does not shrink as voltage falls.
Does the 10 foot rule apply at every voltage?
No. Table 1's first step up is at 50.1 kV, where the distance becomes 10 feet 9 inches, and it keeps rising: 12 feet 4 inches from 72.6 to 121.0 kV, 16 feet 5 inches from 230.0 to 242.0 kV, and 35 feet at 785.0 to 800.0 kV. Cal/OSHA's own Tree Work Safety Guide states the shorthand and then corrects it in the same bullet, noting that approach distances greater than 10 feet are required for higher voltage lines.
Can a certified arborist who is not a qualified line clearance tree trimmer work inside 10 feet of a conductor?
Only under Exception No. 1, and only on low voltage. A qualified tree worker as defined in General Industry Safety Orders section 3420(b) may work within 10 feet, but no closer than 1 foot, of energized lines and conductors at 600 volts or less, provided the provisions of section 3423 related to such work are met. Above 600 volts there is no equivalent, and section 3423(c) reserves the work to qualified line clearance tree trimmers and trainees.
What approach distance applies to a qualified line clearance tree trimmer?
Not Table 1. Section 2950's Note 1 sends qualified trimmers and trainees to section 2951, and section 2951(b) sends them to section 2940.2, where the employer establishes the minimum approach distance by one of the methods in 2940.2(a) rather than reading a fixed figure out of Article 38. Above 3,000 feet of elevation the result is multiplied by an altitude correction factor.
What if a line's voltage falls in one of Table 1's gaps?
Table 1 has no row between 121.0 and 138.0 kV, between 145.0 and 161.0, between 169.0 and 230.0, between 242.0 and 345.0, between 362.0 and 500.0, or between 550.0 and 785.0. Those gaps sit between standard nominal transmission classes rather than inside them. Where a circuit does land in one, section 2951(a) allows the employer to determine the maximum nominal voltage to which an employee will be exposed and treat all lines as energized at it, which resolves to the next row up.
