A pole loading analysis asks one question for every pole on a route: with the new attachment added, can the pole, its guys and its anchors carry every load the code and the owner say they must? This primer explains the forces, the National Electrical Safety Code (NESC) ideas behind them and what the results mean in the field, so you can read an analyst’s report and ask the right questions. It is used in AE-01 Pole Attachment Applications, AE-02 Field Survey and Make-Ready Engineering and AE-03 Make-Ready Execution and Coordination.
What Pole Loading Is
A pole is a cantilever: it is held at the ground and loaded along its length. Every wire, strand, cable, crossarm, transformer and guy attached to it pushes or pulls on it. Wind and ice make those forces larger. A pole loading analysis adds up the forces for the weather cases the NESC and the owner require, applies the code’s margins, and compares the result with what the pole, guys and anchors can hold.
The analysis is run during make-ready engineering in AE-02, after the field survey. It is only as good as the survey behind it: a missed attachment, a wrong pole class or a guess at the lead of a guy changes the answer.
Forces on a Pole
The figure at the top of this page, Forces at a Glance, draws each force as an arrow. An analyst splits the loads into three directions and then checks the bending they cause at the ground.
Vertical Load
Vertical load is the downward force from the weight of the attachments and wires, the ice on them, and the downward part of guy tension. A guy that holds the pole against a sideways pull also presses the pole down into the ground, so adding a guy adds vertical load.
Transverse Load
Transverse load acts across the line. Most of it is wind on the pole and on every wire and cable. At an angle pole, the tension in the wires on each side also pulls the pole toward the inside of the angle, which is why angle poles are usually guyed on the bisector of the angle.
Longitudinal Load
Longitudinal load acts along the line. On a straight run with equal spans, the tension on each side of the pole roughly balances. At a dead-end, or where span lengths or attachments change from one side to the other, the tension is unbalanced and the pole is pulled toward the side with more tension. Angle and dead-end poles carry the unbalanced tension (AE-02), so they are the poles that need the closest look.
Ground-Line Moment
The sideways loads act high on the pole, and the pole resists them at the ground. The bending effect at the ground line is the ground-line moment. The pole’s strength and how it is set in the ground must resist it. Guys exist to take sideways load off the pole so the ground-line moment stays within what the pole can carry.
Loading Districts and Weather Cases
The NESC sets the weather a line must be designed for. The analysis uses the NESC loading criteria for the loading district where the line is built (per NESC Rule 250) and the owner’s criteria.
An analyst usually checks more than one weather case:
- District loading: combined ice and wind for the line’s loading district (per NESC Rule 250B).
- Extreme wind: wind with no ice, where the rule applies (per NESC Rule 250C).
- Extreme ice with concurrent wind: heavy ice with some wind, where the rule applies (per NESC Rule 250D).
Which cases apply, and the wind, ice and temperature for each, come from the adopted NESC edition and the line’s location. Owners can add cases of their own (per owner spec). Ask the analyst which cases governed each pole.
Grades of Construction
A grade of construction is the level of strength the NESC requires a line or structure to meet. It depends on what the pole carries and what it crosses: a pole carrying supply lines over railroad tracks or a limited-access highway may need a stricter grade than the same pole on a quiet road. Stricter grades need more strength margin. The grades and when each applies come from the NESC (per NESC Section 24; per NESC Rules 241 to 243).
A communication-only pole and a joint-use pole carrying power can fall under different grades. The analyst sets the grade for each pole; the report should show it.
Load and Strength Factors
The NESC does not compare raw loads with raw strength. It adds margins, often called safety factors:
- Load factors multiply the calculated loads, so the design load is larger than the expected load (per NESC Rule 253).
- Strength factors reduce the rated strength of the pole, guy or anchor, so the design counts on less than the part’s full rating (per NESC Rule 261).
The factors depend on the grade of construction, the weather case, the material, whether the pole is new or existing, and the NESC edition. Some owners use stricter margins than the code (per owner spec). A report that says a pole “passes” means it passes with these margins applied, under the criteria the analyst used.
Pole Class and Strength
Pole class is a strength rating set by the pole’s dimensions. Read the class and height from the birthmark and the pole tag during the survey, and confirm them against the owner’s records. The analyst turns class, height, species and setting into a rated strength using the pole standard the owner follows.
Strength changes with age and condition. Decay, woodpecker holes, cracks, fire damage and earlier cuts all reduce it. The NESC sets when a deteriorated wood pole must be replaced or rehabilitated, and it checks a new load on an existing pole against the strength required at replacement (per NESC Rule 261, Table 261-1 footnotes). Many owners also require a pole inspection or a strength reduction for older poles (per owner spec). A pole that passes on paper but is rotted at the ground line does not pass.
Steel, concrete and composite poles are rated by their makers and the owner. Their design is outside this primer.
Guys and Anchors
A guy takes sideways load off the pole and sends it to the ground through an anchor. Down guys and anchors are built in AE-06 Anchors and AE-07 Down Guys and Guy Guards.
- Down guy: strand from the pole to an anchor, set against the pull it balances (down guy). At a dead-end it resists longitudinal load; at an angle, a bisect guy resists transverse load.
- Span guy and sidewalk guy: used when an anchor cannot be set in line with the load (span guy, sidewalk guy).
- Lead: the distance from the pole to the anchor (lead). A short lead makes the guy steeper. For the same sideways load, a steeper guy carries more tension and pushes the pole down harder.
- Attachment height: a guy works best attached near the load it balances. A guy attached well below the new strand leaves part of the pull on the pole as bending.
The guy strand, the guy grips and the anchor each have a rated strength, reduced by strength factors in the analysis. Anchor holding power also depends on the soil. Anchor and guy sizes come from the owner standard and the manufacturer (per owner spec).
Joint Use and Existing Attachments
Most poles carry more than one owner’s facilities under joint use and pole attachment agreements. The analysis has to include every load on the pole, not only yours:
- power conductors, the neutral, transformers, crossarms and streetlights;
- every existing communication attachment, including any overlashing;
- existing guys and anchors, and whether they are still sound.
This is why AE-02 measures every pole instead of trusting old records. A new attacher’s load can push a pole that was already near its limit over the line. Who fixes a pole that already fell short before your attachment, and who pays, depends on the rules that apply. In FCC-regulated states, the federal rules limit what a pole owner can charge a new attacher to correct a violation it did not cause (47 CFR 1.1401 and following § 47 CFR 1.1411(e)(4)). Where your load alone is what pushes a sound pole over, the make-ready cost of the fix is usually yours. If the pole already failed the code or was already due for replacement, the FCC rules generally limit your share to the extra cost of the taller or stronger pole your attachment needs. FCC rules do not cover poles owned by cooperatives, governments or railroads, or poles in states that regulate attachments themselves; there, state rules and the attachment agreement govern (per attachment agreement and state rules).
How Results Drive Make-Ready
Each pole comes out of the analysis with one of a few results. The result is what the make-ready list in AE-02 is built from.
| Result | What It Usually Means in the Field |
|---|---|
| Passes as designed | Attach at the proposed height with the planned hardware. |
| Passes with a rearrangement | Existing attachments move to make room or to balance the load. |
| Needs a new or larger guy | Add or upgrade a guy and anchor, often at an angle or dead-end pole. |
| Needs a stronger or taller pole | Replace the pole, and transfer every attachment to the new pole. |
| Cannot be fixed on this pole | Redesign: reroute, change the attachment or go underground. |
Rearrangements, transfers, power work, guying and pole replacements become the make-ready list for each pole. Where Federal Communications Commission (FCC) or state rules use simple and complex make-ready, the class decides who can do the work and on what schedule (AE-02). AE-03 coordinates the work, and framing does not start in a section until make-ready is complete and verified on every pole in it.
Ask these questions when you read a report:
- Which NESC edition, weather cases and grade of construction were used for each pole?
- Which owner criteria were applied, and were they stricter than the code?
- Were all existing attachments, guys and anchors from the survey in the model?
- Which poles failed, and was each failure fixed with a guy, a rearrangement or a replacement?
- Were the angle and dead-end poles modeled, not just the tangent poles?
Safety
Where Rules Differ
- NESC edition. Most states apply the NESC, in whole or in part, and the edition in force varies by state. California uses its own overhead line rules instead (below). Design to the rule and edition your state applies (AE-02).
- Owner criteria. Pole owners can require stricter weather cases, larger margins, extra inspections or replacement rules beyond the code (per owner spec).
- In California, overhead lines are built per CPUC General Order 95 rather than to the NESC, so check the state rule before reading any loading result.
- Attachment rules. FCC rules or state rules set the make-ready process and timelines, and the attachment agreement sets what the owner requires in the application.
Standards and References
NESC (IEEE C2) § Rule 250for loading. Grades of construction and load and strength factors come from the same code; the rule chips above are on the SME review list until they are checked against the adopted edition.- Owner construction standards and loading criteria, including the analysis software settings and strength margins the owner requires.
- Power owner requirements for guy insulators, bonding and work in the supply space.
- The owner attachment agreement for each pole owner.
29 CFR 1910.268for telecommunications maintenance and service. It excludes construction work, which falls under OSHA’s construction standards. OSHA scope decides which applies; your employer’s safety program says how to comply.47 CFR 1.1401 and followingor state rules for the make-ready process.
On the Map
- Utility Pole: the structure the analysis checks, with power at the top and communication attachments below.
- Pole Tag and Birthmark: where the survey reads the pole’s class and height.
- Down Guy: the strand that balances the line’s unbalanced tension.
- Anchor and Anchor Rod: holds the guy in the ground, set in line with the load.
- Span and Sidewalk Guys: guying for poles where an in-line anchor cannot be set.
- Preformed Guy Grip: terminates the guy at the pole and the anchor; part of the guy’s rated strength.
- Strand Dead-End: where strand terminates and longitudinal load is greatest.
- Messenger Strand: the tensioned strand whose pull the poles and guys carry.
- Communication Space: where the new attachment goes.
- Supply Space: power facilities whose loads count in the analysis, worked only by qualified electrical workers.
Related Steps
- AE-01 Pole Attachment Applications: the application that usually includes the loading results.
- AE-02 Field Survey and Make-Ready Engineering: the survey and the loading analysis.
- AE-03 Make-Ready Execution and Coordination: the field work the results call for.
- AE-07 Down Guys and Guy Guards: building the guys the analysis requires.