Steel Multi-sided Poles for 35 kV Lines

Types of poles for 35 kV lines

We prepare the KM stage design and manufacture multi-sided poles for 35 kV overhead lines; we can also prepare KMD drawings if needed. Intermediate double-circuit poles are used to carry steel-aluminium conductors up to AC 120/27. All poles are regular polygons in section.

Intermediate poles are set in drilled pits to a depth of 3.0 m; a version with a flanged fixing to a foundation is also possible. The steel shafts are assembled from several sections with a slip (telescopic) joint. Double-circuit poles (end, angle-anchor and intermediate) are made with three shafts fixed in a drilled pit to a depth of 3.0 m or by flanges; a single-shaft pole can be designed for special conditions. The shafts of anchor poles are also assembled with a slip joint.

Climbing multi-sided steel poles is recommended from telescopic lift platforms, with stock ladders or with special stock lifting devices. Fixed ladders are provided for climbing above the lower crossarm; if wished, the whole shaft of the pole can be equipped with fixed ladders.

Manufacture

The steel structures are made to technical conditions agreed with the authors of the design. All elements of the poles are designed to meet the requirements for articles to be hot-dip galvanised to DSTU EN ISO 1461:2024. The surface of the steel shafts, 3.5 m from the butt, has a bitumen coating at least 3 mm thick or another insulating coating.

The shafts are fitted with top caps and stiffening diaphragms at the butt, which also serve as bearing elements for the pole in the ground. The lower and middle sections of the shafts have stiffening diaphragms at the top to prevent the slip joint from being crushed while the pole works under design loads.

Scope of application

Steel poles for 35 kV lines are meant for use in wind regions I–V and ice regions I–IV, in populated and unpopulated areas. The angle-anchor pole allows a maximum line angle of 79°.

The fixing in the ground of intermediate and anchor poles is normally made without a crossbar in a drilled pit 3 m deep; where needed a crossbar is fitted by calculation. The pits are backfilled with a sand-gravel or sand-cement mixture. Earthing is carried out to the Rules for the Arrangement of Electrical Installations (PUE), 2026 edition; its requirements are set out in the section below.

Finished elements must be slung in ways that leave no permanent deformation, dents or damage to the galvanised coating; shafts are stacked on wooden supports. When erecting poles, conductors and earth wires the general construction safety rules are followed.

Earthing of 35 kV pole lines under the PUE

Under the Rules for the Arrangement of Electrical Installations (PUE), 2026 edition, metal and reinforced-concrete poles of 35 kV lines are to be earthed (cl. 2.5.127). For every line of this voltage the resistance of the earthing arrangement must not exceed the value in Table 2.5.29, which depends on the equivalent soil resistivity ρ: 10 ohms at ρ up to 100 ohm·m, 15 ohms at ρ above 100 up to 500, 20 ohms at ρ above 500 up to 1000 and 30 ohms at ρ above 1000 up to 5000 ohm·m. For ρ above 5000 ohm·m the value comes from the formula in the table itself. For poles of mountain lines standing more than 700 m above sea level, the table values may be increased threefold.

For poles with an earth wire or other lightning protection, the table value holds up to a pole height of 50 m; above 50 m the resistance must be half of it. On double-circuit and multi-circuit poles, halving the table value is recommended whatever the height (cl. 2.5.127).

The required resistance must be achieved with artificial earth electrodes; the natural conductivity of foundations and of the underground parts of poles need not be counted in the calculation (cl. 2.5.130). For a shaft in a drilled pit or on a flanged foundation this means that the resistance has to be provided by a purpose-built earth electrode.

Each earthing conductor (down-lead) on the pole must have a cross-section of at least 35 mm² and, if single-wire, a diameter of at least 10 mm; on metal poles their joints may be threaded or welded (cl. 2.5.132). Earth electrodes are, as a rule, laid at a depth of at least 0.5 m, and in arable land at 1 m (cl. 2.5.133). For the poles of a 35 kV line nearest to an outdoor switchgear, the resistance of the earth electrodes must not exceed 10 ohms (cl. 4.2.166). For a specific line the designer takes the final values from the current text of the PUE and from soil resistivity measurements along the route.

Why these poles beat the alternatives

A closed, solid multi-sided profile can be fully hot-dip galvanised, while lattice poles often contain lap-welded joints without a closed seam, which galvanising rules do not allow — this gives multi-sided poles a longer service life than lattice or reinforced-concrete alternatives. See Transmission Poles: Multi-Sided, Lattice or Reinforced Concrete for details.

Advantages of multi-sided poles for 35 kV lines

• lower weight than lattice poles and less transport and loading work;
• compactness: suitable for urban and restricted conditions where there is no room for a wide base;
• the shaft sections are easy to transport, and installation does not require assembling a large number of elements;
• protection by hot-dip galvanising to DSTU EN ISO 1461:2024 and a closed profile, less prone to corrosion and vandalism.

What is needed for calculation and ordering

Send the route diagram with angles, the conductor type and cross-section, the wind and ice region, the type of insulation and the foundation requirements. If you have KM drawings, we will quickly prepare KMD and pass them to production; if not, we will develop KM. You can fill in the technical specification form for a power line pole further down the page.

Price and lead time

For the approximate price of 35 kV line poles see the page Power Line Pole Prices. Delivery and installation are not included in it and are calculated separately, and the installation is carried out by a licensed construction partner company. The typical lead time is 3–4 weeks if the product is not in stock; for large batches and non-standard poles we confirm the exact lead time after the calculation.