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A wood utility pole is a treated tree trunk set in the ground to carry power or communication lines. In the US, wood poles are specified under ANSI O5.1 by length, in 5 ft steps, and by class, from H6, the strongest, down to Class 10. Each class is sized to hold a set horizontal load applied 2 ft from the top.
A peeled, pressure-treated log that works as a simple cantilever: fixed in the ground, loaded from the side by wind on wires and equipment.
Wood is still the most common pole material in the US. The Department of Energy (DOE) puts the count at about 130 million wooden poles out of roughly 180 million utility poles in total.
The main US standard is ANSI O5.1, Wood Poles: Specifications and Dimensions, maintained by Accredited Standards Committee O5. The current edition, O5.1-2022, was approved in August 2022. It sets wood quality limits such as knots and sweep, the minimum size for every length and class, and a design fiber strength for each species.
Wood also handles easily. The North American Wood Pole Council, an industry group, notes that wood poles can be climbed with standard tools, drilled in the field, and set with standard digger-derrick trucks up to about 70 ft.
BIDR supplies Southern Yellow Pine, Douglas Fir and Ponderosa Pine. Other species, such as Western Red Cedar, are also in the market.
In the ASC O5 chair's overview of the standard, Southern Yellow Pine is the usual distribution pole east of the Rocky Mountains and Douglas Fir the usual distribution pole in the West. Douglas Fir and Western Red Cedar are common for transmission. ANSI O5.1 also lists Ponderosa Pine, along with species such as Lodgepole Pine, Jack Pine, Red Pine and Western Larch.
ANSI O5.1 assigns a design fiber strength of 8,000 psi to Southern Yellow Pine and Douglas Fir and 6,000 psi to Western Red Cedar. Poles of the same length and class carry about the same load whatever the species, so a weaker species is simply thicker. A 40 ft Class 4 Douglas Fir pole is about 33.5 in around at the groundline (where the pole meets the soil); the Western Red Cedar equivalent is about 36.5 in.
Most Douglas Fir pole users also through-bore or incise the groundline zone to drive preservative deeper, a practice the wood pole council says markedly reduces internal decay.
Class sets strength and length sets height. A spec needs both.
Each ANSI O5.1 class is defined by a horizontal load applied 2 ft from the top of the pole. For every length, the standard sets the minimum circumference at the top and at 6 ft from the butt (the bottom end) needed to carry it. Lower numbers are stronger, and the H classes are stronger again. There is no Class 8.
A longer pole of the same class is thicker at the base, because the load acts on a longer lever: 2,400 lb on a 40 ft Class 4 pole makes 76,800 ft-lb at the groundline, and 98,400 ft-lb on a 50 ft Class 4.
| Class | Horizontal load 2 ft from top (lb) | General use in the ASC O5 overview |
|---|---|---|
| H6 | 11,400 | Transmission |
| H5 | 10,000 | Transmission |
| H4 | 8,700 | Transmission |
| H3 | 7,500 | Transmission |
| H2 | 6,400 | Transmission |
| H1 | 5,400 | Transmission |
| Class 1 | 4,500 | Transmission |
| Class 2 | 3,700 | Distribution or transmission |
| Class 3 | 3,000 | Distribution or transmission |
| Class 4 | 2,400 | Distribution |
| Class 5 | 1,900 | Distribution |
| Class 6 | 1,500 | Telecom only |
| Class 7 | 1,200 | Telecom only |
| Class 9 | 740 | Telecom only |
| Class 10 | 370 | Telecom only |
The use groupings are general. Each utility writes its own standard: Ameren's distribution standard, for example, stocks Class 1 and H-class poles. Lengths step in 5 ft increments; the same standard lists Southern Yellow Pine from 30 to 90 ft and Douglas Fir up to 125 ft.
The common rule of thumb is to bury 10% of the pole's length plus 2 ft. A 40 ft pole goes 6 ft deep; a 45 ft pole goes 6.5 ft. The wood pole council calls it the standard setting depth.
Treat it as a starting point. Ameren uses 10% plus 2 ft for Class 1 and smaller poles, 10% plus 3.5 ft for Class H1 and larger, and adds 12 in for average and poor soil. In poor soil the wood pole council suggests gravel backfill and 10% plus 4 ft. Setting deeper changes the groundline moment and conductor height, so recheck the loading. Whatever the depth, backfill with good soil and tamp it hard.
Untreated wood decays in the ground. Treatment gives a wood pole its service life.
Poles are pressure-treated at a treating plant to American Wood Protection Association (AWPA) standards. AWPA U1, the Use Category System, sets which preservatives and retentions (the amount of preservative left in the wood) work for each exposure. AWPA T1 covers the treating process. AWPA also maps decay hazard zones, and poles bound for harsher zones are treated to higher retentions.
Chromated copper arsenate is a water-borne preservative. Makers stopped producing CCA-treated wood for homeowner uses in December 2003, but EPA still lists commercial wood poles among its uses.
EPA lists creosote for outdoor wood such as railroad ties and utility poles. Only certified applicators at treating plants apply it.
Penta was used mainly on utility poles. EPA's February 2022 decision requires its cancellation: production, sale and distribution ended February 29, 2024, and treating plants may use existing stock only until February 28, 2027. EPA names copper naphthenate and DCOI (which EPA writes as DCOIT) as alternatives. EPA's page does not call for removing penta-treated poles already in service.
Buyers financed by the USDA Rural Utilities Service also cite RUS Bulletin 1728F-700, its specification for wood poles, stubs and anchor logs, which points to AWPA U1 and T1 for treatment.
DOE's 2024 resilience guide says wood pole lifetimes are generally estimated at 30 to 50 years, with wide variation because inspection and maintenance practices differ.
The National Electrical Safety Code (NESC) requires a wood pole to be replaced or rehabilitated when deterioration reduces its strength to two-thirds of the strength required when it was installed. Utilities check this with groundline inspections that include sounding and boring, and for some species digging around the pole. DOE notes a shift toward "conditioned" methods that measure how far decay has gone, not just whether it is present.
Remedial treatment adds years. A national inspection data review cited by the wood pole council put average life without remedial treatment at 45 years, and found that inspection and remediation extend it significantly.
| Item | On the contract |
|---|---|
| Heights | 25 to 70 ft, in 5 ft steps |
| Classes | Class 1 to Class 5 |
| Species | Southern Yellow Pine, Ponderosa Pine, Douglas Fir |
| Treatment | CCA or creosote, for each species |
| Hardware | Wood, steel and fiberglass crossarms, braces, gain blocks, anchors, guy wire and grips, pole caps, bolts, ID tags, insulators |
| Field services | Delivery and site drop, installation, inspection, treatment remediation, old pole removal and disposal, 24/7 emergency storm response, pole loading analysis |
| Delivery area | Contiguous US; Alaska and Hawaii quoted separately |
The BIDR Utilities catalog lists 450 pole specifications, including galvanized steel, spun concrete and composite poles. Sourcewell, a Minnesota local government unit, ran the competitive solicitation (#11229), and its page lists one awarded contract: BIDR Technologies, Sourcewell Contract #060326-BIDR, through August 5, 2030.
Your agency stays responsible for its own due diligence. Related guides: cooperative contracts, utility pole cost and utility pole materials.
It is a strength rating. Each ANSI O5.1 class is sized to hold a set horizontal load 2 ft from the top: 4,500 lb for Class 1, 3,000 lb for Class 3 and 1,900 lb for Class 5. Lower numbers are stronger, and H1 to H6 are stronger still. Length is a separate callout, as in 45 ft Class 3.
The usual rule of thumb is 10% of the pole's length plus 2 ft, so a 40 ft pole is set 6 ft deep and a 50 ft pole 7 ft. Utilities add depth for poor soil and for heavier H-class poles. Follow your own construction standard or an engineer's pole loading analysis, which BIDR offers as an engineering service.
New supply is ending. EPA decided in February 2022 to cancel pentachlorophenol. Sale and distribution of the preservative ended February 29, 2024, and treating plants may use existing stock only until February 28, 2027. EPA names copper naphthenate and DCOI as alternatives. BIDR's catalog offers wood poles treated with CCA or creosote.
Yes, if it is a Sourcewell participating entity. Sourcewell competitively solicited the utility pole contract and awarded Sourcewell Contract #060326-BIDR to BIDR Technologies. Registered agencies request a quote and issue a purchase order against the contract. Registration is free and carries no obligation to buy. Your purchasing office still confirms the contract fits your own rules.
Send length, class, species, treatment, quantity and delivery site. You get a written quote at Sourcewell contract pricing with a delivery timeline.