Pre-inspecting a distribution cycle and a transmission cycle: what differs

A distribution pre-inspection starts with an assigned circuit and a walk. Its default prescription is a prune sized to hold two to three annual cycles. A transmission pre-inspection starts with an aerial LiDAR delivery and a ranked detection list. Its default prescription is to fell. On a NERC line the calendar comes from FAC-003-5 Requirement R6.

Two vegetation pre-inspections can happen on the same afternoon, a mile apart, under conductors that look broadly alike from the road. One of them is governed by a state clearance rule and a utility procedure. The other is governed by those and by a federal reliability standard with a calendar year in it. Almost everything that differs between a distribution cycle and a transmission cycle follows from that second sentence.

The worked example here is PG&E, because PG&E publishes both procedures and a contractor can read them. The distribution side is Utility Procedure TD-7102P-01, "Vegetation Management Distribution Inspection," Revision 4, effective November 15, 2025.

The transmission side is Utility Standard TD-7103S, "Vegetation Management Transmission Program" and Utility Procedure TD-7103P-01, "Vegetation Management Transmission Inspection", both Revision 4, both published November 27, 2024 and effective January 27, 2025. One utility's procedures bind that utility alone. They are useful here because they are the same company answering the same question twice and arriving at different answers.

Two programs meet at 60 kV, and only one of them answers to NERC

TD-7103S defines what the transmission program covers by voltage:

Facilities (Transmission): The components of the electric Transmission line overhead system, including conductors (from 60 kV to 500 kV), steel structures, non-steel structures, insulators, switches, and Substations.

It defines the federal subset separately:

NERC-Regulated Transmission Lines (NERC lines): Transmission lines operated at 200 kV or higher and certain sub-200 kV lines that are elements of a Major Western Electric Coordinating Council (WECC) Major Transfer Path (MTP).

A 115 kV circuit is not outside the transmission program. It is outside the NERC list. That single distinction reappears at every stage of the cycle below, and getting it backward is the most expensive mistake available on this subject, because it sets the clock, the detection ranks and the hazard tree horizon all at once. Which lines the federal standard actually reaches, and how a sub-200 kV line gets designated is a determination made outside vegetation management.

It is also a determination that arrives on a schedule. TD-7103S section 6.3 says where from:

An annual assessment of NERC lines will be provided by the PG&E Transmission Planning team, disseminated to VASA and VM Operations through the common inbox: NERC-TPL-001-TP@pge.com.

The list is refreshed once a year by another department and sent to an email address. A program manager who has never seen that message has never seen the scope of the year's federal obligation.

One cycle opens with a circuit, the other with a flight

A distribution inspector is issued an assigned circuit or project area, a pre-patrol report and historical outage data, and then walks it. The transmission inspector is issued a list of points.

TD-7103S section 2.1 states that annual transmission inspection "uses light detection and ranging (LiDAR) technology to identify potential tree risk," and that "ground patrols are informed by the LiDAR detections identified." TD-7103P-01 section 3.1 draws the consequence in one sentence:

IF Aerial LiDAR information exists for a transmission line (T-line), THEN the VMI does not need to perform ground patrol of the entire line segment.

The inspector goes to the detections and to the spans the detections sit in. The patrol plan comes from Appendix B of the procedure rather than from the map. That is a different job from walking a circuit pole to pole. It is also a different skill. The transmission inspector is field verifying somebody else's measurement and deciding whether the vendor's point is real.

The exception is worth knowing, because it is the one place the transmission cycle looks like the distribution cycle. TD-7103S section 2.1 states that commercial nut-producing orchards are inspected by ground patrols, with LiDAR informing minimum ground to conductor clearances in orchard spans. Under an almond canopy the laser cannot do the work. What an agricultural corridor asks of the inspection instead is its own subject.

Two calendars, and only one of them starts on January 1

Requirement R6 of NERC Reliability Standard FAC-003-5 reads:

Each applicable Transmission Owner and applicable Generator Owner shall perform a Vegetation Inspection of 100% of its applicable transmission lines (measured in units of choice - circuit, pole line, line miles or kilometers, etc.) at least once per calendar year and with no more than 18 calendar months between inspections on the same ROW

Two clocks run at once and both have to be satisfied, which the requirement by requirement reading of the standard sets out. What matters on the ground is that the calendar year is the outer container, so work done in December does not count toward the following year and work done in January starts a fresh one.

TD-7103P-01 section 1.2 schedules against that directly. NERC ground inspections begin after January 1. Non-NERC ground inspections begin after November 15, or earlier if directed by PG&E leadership. The LiDAR analytical reporting follows the same split: non-NERC reports arrive as data is processed, NERC reports arrive after January 1.

The urgency clocks split the same way.

What	NERC lines	Non-NERC transmission
Ground inspection opens	After January 1	After November 15
LiDAR analytical report	After January 1	As data is processed
Field verification of an urgent critical detection	2 business days from vendor receipt	10 business days from vendor receipt
Deadline to complete identified tree work	December 31 of the same year	Within one year of identification

Sources for the table are TD-7103P-01 sections 1.2 and 2.2, and TD-7103S sections 2.1 and 5.3. The two business day figure is the one to carry into a staffing plan. It means a vendor delivery on a Friday is a Tuesday field visit, in whatever terrain the line crosses.

A distribution routine patrol has no equivalent fixed date. Its assessment timeframe is the next Routine annual inspection cycle, and a Hazard Patrol looks ahead approximately six months. Where the distribution vegetation cycle actually comes from, given that General Order 165 does not set one is a separate question with a longer answer.

The default prescription runs the other way

This is the difference a crew notices first. Both procedures give the inspector a ladder, and the ladders start at opposite ends.

	Distribution, TD-7102P-01 Rev 4 Table 4	Transmission, TD-7103P-01 Rev 4 section 4 and TD-7103S section 2.3
First choice	Prune so vegetation maintains compliance for 2 to 3 Routine annual inspection cycles	Fell all trees less than 24 inches DBH, as a best management practice
Second choice	Prune to maintain compliance for one Routine annual cycle	Prune with multiple years of clearance, at minimum one year of clearance
The bi-annual case	Bi-Annual clearance after PG&E VM Representative approval	Fell, with no pruning option offered
Palms	Covered by the general ladder	Fell, as a best management practice

TD-7103P-01 section 4.3 puts the bi-annual rule in one line:

PRESCRIBE felling for all vegetation requiring bi-annual (twice yearly) pruning.

On distribution the same situation is an approval request. On transmission it is a removal. The 24 inch diameter at breast height threshold is the other half of the rule, and it cuts both ways. Section 4.4 of the same procedure covers vegetation growing into a structure or a guy wire. For a tree of 24 inches DBH or greater there, the options are pruning or no work, and felling takes a consultation with the VPL.

Behind the ladder sits a different objective. TD-7103S section 2.3 tells the inspector to prescribe "to achieve full enjoyment of the applicable Transmission right-of-way (ROW) easement document or agreement associated with the property parcel," and states that "the desired outcome is to fell incompatible trees when tree work is required."

The transmission prescription is aimed at the corridor, not at the conductor. How wide that corridor is, and where the width comes from decides how much of the parcel the prescription reaches. Which prescription the inspector writes and on what grounds is the general version of this question.

Overhang is prescribed the same way. In a High Fire-Threat District the inspector lists for work any rank 7 detection with vegetation within 0 to 6 feet of the outside transmission wire, and the procedure names the result: "a clear-to-sky Extended Overhang zone beyond the transmission conductors." Outside an HFTD the same rank 7 band is 0 to 2 feet. Which tier a span sits in therefore changes the shape of the cut and not only the distance.

The same dead tree, held to two horizons

TD-7103P-01 defines Hazard Tree in layers, and one of the layers applies to NERC lines only:

All Lines: Trees that are dead or show signs of disease, decay, or ground or root disturbance which might fall into or otherwise impact the conductors, towers, or guy wires before the next inspection cycle. NERC lines only: In addition, trees within the easement with a potential to fail within the next two years (as assessed by the VMI), which would pass within the PG&E minimum clearance requirements.

Stand in front of a declining valley oak inside the easement. On a line that is not on the NERC list, the question is whether it will fail before the next inspection cycle.

On a 230 kV NERC line the question becomes whether it will fail within two years, and whether the failure path would carry it inside 10 feet of the conductor. The same tree can be a no work record on one line and a felling prescription on the other, and the only variable that moved is which line it stands under.

Two years is a long assessment to defend from the road. The distribution procedure reaches the same class of tree through a Level 1 inspection that escalates to a Level 2 where defects are seen, and through the Elevated work category, which requires a Tree Risk Assessment form and a TRAQ qualification for strike trees. What the assessment levels are, what a Level 2 leaves blank, and who is qualified to sign one is the machinery both cycles borrow. The horizon is what differs.

Where the conductor is allowed to be

A distribution inspector measures against the Minimum Distance Requirement and projects growth to the next annual cycle. Table 3 of TD-7102P-01 asks that inspector to "CONSIDER normal weather patterns for the local area, line position, and line conditions." It supplies no modeled conductor position to measure from.

Transmission does not treat the wire as fixed. Appendix B of TD-7103P-01 ranks every detection by which conductor position was modeled when the measurement was taken.

• As flown: the conductor where the aircraft found it.

• Maximum operating conditions: the conductor at its rated sag. Rank 2, the urgent grow-in under this model, applies to NERC lines only.

• Modeled blowout: the conductor position "modeled at 56 mph wind." Ranks 9 and 10, applied in High Fire-Threat Districts and on NERC lines only, with a tree record required at rank 9 on NERC lines.

Rank 1, the as flown urgent grow-in, is set at 15, 10, 10 and 4 feet for 500, 230, 115 and 60 or 70 kV. Those are the PG&E Minimum Clearance Distances exactly, so a rank 1 detection is a report that vegetation is already inside the number the program prescribes to.

The distances are measured from the modeled conductor, not from where the aircraft found it. A tree standing well clear of a 230 kV conductor on the day of the flight can still be a rank 9, because the model walks the conductor toward it. At 230 kV the rank 9 band is 6 feet from the blown out position. The inspector who walks up to that tree is being asked about a conductor position they cannot see.

That is what Requirement R3 of FAC-003-5 means when it makes the documented strategy account for conductor movement. It is also why the prescription is written against the PG&E Minimum Clearance Distance rather than against the much smaller MVCD. Appendix A of TD-7103S sets it by voltage.

Voltage	PG&E Minimum Clearance Distance
60 or 70 kV	4 ft.
115 kV	10 ft.
230 kV	10 ft.
500 kV	15 ft.

The distribution side has its own version of this on idle plant, and both procedures agree on it. TD-7103P-01 section 4.3 directs the inspector to "TREAT all Idle, de-energized, and lower voltage lines attached pole to pole as energized at the designed transmission voltage." A line running at distribution voltage on transmission structures is inspected as transmission.

A span with nothing wrong still makes a record

This is the part a distribution inspector moving onto transmission gets wrong. It is also the first thing an auditor asks about. Appendix B of TD-7103P-01 states the rule:

LiDAR Detections Rank 1-16 require at least one location record to show proof of Span Inspection.

A detection the inspector looks at and dismisses still produces rows. Where no prescription is required on a rank that would otherwise carry a tree record, Appendix A directs the inspector to do three things:

• Record the tree with a Priority Type of No trim and a Notification Type of Inventory.

• Enter the LiDAR detection code in Tree Comments.

• Enter an explanation of why no prescription is listed.

The span itself gets a location record documenting that it was inspected.

Read that against R6 and the reason is plain. The requirement is 100 percent coverage of applicable lines, and the measure accepts "completed and dated work orders, dated invoices, or dated inspection records." Coverage is proved by rows. A program that only creates rows when it finds work cannot demonstrate it inspected anything else. What the system of record has to be able to do with entries like these is a separate decision, made before the cycle opens rather than during it.

One category is deliberately outside the count. Tower, pole and guy wire clearing is a best management practice under section 4.4 and "is NOT considered annual work performed during a routine cycle." It gets its own location record, with CC1A in the SSD number field and the tower or pole number in Location Comments. Work that can be started and stopped on operational need is kept out of the number that has to reach 100 percent.

The landowner appears in one procedure and not the other

TD-7102P-01 Revision 4 spends a numbered section on notification. The inspector attempts contact, documents the method, the name, the date and time and the outcome, and attempts up to two more times if there is no response. How that notification record travels with the unit is the distribution pre-inspection's most reconstructible artifact.

TD-7103P-01 Revision 4 contains no notification steps. Notification appears as a field in the Project Management Database, as a third party utility notification, as part of the imminent threat path, and once for orchards, where the inspector is told to contact the VPM about a notification of potential work. Customer interference is sent out to TD-7103P-07, a separate transmission interference procedure. A constraint is documented in the system of record and worked with the VPL or VPM.

The asymmetry is a consequence of where the work happens. Distribution runs along streets, through backyards and across frontages with an owner at every parcel. Transmission runs in a corridor the utility holds rights in, and the prescription is written to the extent of those rights. The landowner conversation still happens on transmission.

It happens under a different procedure, and the pre-inspection record does not carry it. What notice a utility owes and what a refusal entitles it to do does not change with voltage, and the workflow a refusal opens is written for the distribution codes.

The underbuilt pole, where one inspector writes both prescriptions

The most common place the two cycles collide is a 60 or 70 kV transmission circuit with 12 to 21 kV primary distribution underbuilt on the same pole. Both procedures address it, and they address it to the same person.

TD-7103P-01 section 8.1:

In Underbuilt locations, the distribution VMI must PRESCRIBE work to the transmission specifications.

TD-7102P-01 Revision 4, Table 3, gives that same distribution inspector three instructions for an underbuilt span:

• Evaluate the Minimum Distance Requirement or the Minimum Clearance Distance, based on anticipated growth rates before the next Routine annual inspection cycle.

• Prescribe work that would satisfy clearance requirements for both distribution and transmission lines.

• Add comments about transmission clearance to the system of record.

Those instructions are compatible on the clearance and divergent on everything else. The transmission specifications say fell a tree under 24 inches DBH, fell anything needing twice yearly pruning, and clear the overhang to sky in an HFTD. The distribution ladder says prune for 2 to 3 cycles. An inspector holding a 16 inch DBH ornamental under an underbuilt span is being pointed at a removal by one document and a prune by the other, on a parcel where the owner is standing in the driveway.

Neither procedure resolves it in text. TD-7103P-01 section 4.2 names who does:

IF the tasks in step 4.1 are not achievable, THEN the VMI must ESCALATE the issue to the VPL, VPM, SVPM (or Delegate). Adjustments to Prescriptions are at the discretion of PG&E VPM, SVPM (or Delegate).

The prescription belongs to the utility. The inspector's job at that pole is to write down what both specifications require, name the conflict, and send it up. The authority an inspector carries in the field, and the line between what they decide and what the procedure escalates is the same in both programs.

Marking is where the collision becomes visible to a crew. Appendix G of TD-7103P-01 rotates paint colors on a four year cycle and offsets the two programs against each other. In 2026 the distribution routine program marks in red and the transmission routine program marks in orange. A dot means pruning and an X means felling in both. An orange X and a red dot on the same trunk are a legible statement about which program wants what, and a crew reads them from the truck.

What is left open, and who decides it

Three things in this comparison are not settled by any rule. It is worth being clear about which.

The method of inspection is open. R6 requires the Vegetation Inspection and sets the coverage and the interval. The NERC Glossary adds only that it "may be combined with a general line inspection." Nothing federal says aerial, ground, LiDAR or otherwise. TD-7103P-01 section 3.1 is the utility's answer to a question the standard left to it, and a different transmission owner may answer it differently and still comply.

The distribution cycle length is open in the same way. FAC-003-5 reaches applicable transmission lines and stops. For distribution the cycle comes from the utility's own program and its wildfire mitigation plan commitment rather than from an inspection interval in General Order 165 or a distance in General Order 95 Rule 35.

The contract is where a prime finds the rest. TD-7103S section 5.2 points pre-inspection services at a document outside the procedure set: "SPECIFIC CONDITIONS NO. 4851 FOR VEGETATION MANAGEMENT PRE-INSPECTION SERVICES," dated November 21, 2023. Both inspection procedures, TD-7102P-01 and TD-7103P-01, carry a Level of Use of Informational Use. What is enforceable against a contractor running either cycle is in the specific conditions and the contract that names them, and a prime bidding transmission pre-inspection without having read 4851 is bidding on the procedure alone.

Both transmission documents here were read on September 20, 2026, at Revision 4, effective January 27, 2025. Revision numbers move, and a public copy and a filed copy of the same procedure are often not the same revision. Which revision a prime is actually working to, and who decides that is worth settling before any of this reaches a field guide.

Common questions

Further reading

• What a pre-inspection produces: The unit of work both cycles hand to a crew, and the fields inside it.

• FAC-003-5, requirement by requirement: The federal standard that puts a transmission cycle on a calendar year.

• Right of way width and the easement: Why a transmission prescription is written to a corridor boundary.

Frequently asked questions

Does FAC-003-5 say how a transmission line has to be inspected?

No. Requirement R6 sets the coverage and the clock, not the method: a Vegetation Inspection of 100 percent of applicable lines "at least once per calendar year and with no more than 18 calendar months between inspections on the same ROW." The NERC Glossary definition of Vegetation Inspection adds only that it "may be combined with a general line inspection." How the inspection is performed is the utility's decision. PG&E's decision is written into TD-7103P-01, which states that where aerial LiDAR information exists for a transmission line, the inspector "does not need to perform ground patrol of the entire line segment."

Is a 115 kV line a transmission line for vegetation purposes?

For PG&E's program, yes. TD-7103S defines transmission Facilities as conductors from 60 kV to 500 kV, and the Transmission Annual Patrol covers all of them. For NERC, only if it has been designated. TD-7103S defines NERC lines as those "operated at 200 kV or higher and certain sub-200 kV lines that are elements of a Major Western Electric Coordinating Council (WECC) Major Transfer Path (MTP)." A 115 kV circuit is inside the transmission program and outside the NERC list, and the two produce different clocks, different detection ranks and different hazard tree horizons on the same span.

Can one inspector cover a span that carries both?

Yes, and both procedures say who writes what. TD-7103P-01 section 8.1 states that in underbuilt locations "the distribution VMI must PRESCRIBE work to the transmission specifications." TD-7102P-01 Revision 4, Table 3, tells the same inspector to prescribe work that satisfies clearance requirements for both lines and to add comments about transmission clearance to the system of record. The two sets of specifications do not produce the same prescription from the same tree, and TD-7103P-01 section 4.2 sends the disagreement to the PG&E VPM or SVPM.

Why does the transmission inspection procedure have no notification section?

Because the transmission cycle works a corridor the utility already holds rights in. TD-7103P-01 Revision 4 contains no landowner notification steps at all. Customer interference is routed out to TD-7103P-07, and a constraint is documented in the system of record and worked with the VPL or VPM. The distribution procedure, by contrast, spends a numbered section on contact attempts and the fields each one has to carry.

What does a transmission inspector record on a span where nothing needs work?

A location record. Appendix B of TD-7103P-01 states that "LiDAR Detections Rank 1-16 require at least one location record to show proof of Span Inspection." Where a detection that would normally require a tree record turns out to need no work, the inspector records it with Priority Type of No trim and Notification Type of Inventory, enters the detection code in Tree Comments, and enters an explanation of why no prescription is listed. That record is the evidence of coverage, and coverage is what R6 measures.