Wooden Electricity Pole Sizes: How to Choose Class H, O or A
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Why do two poles of the same length differ, and which one belongs on which line? We explain length and class with a table.
Wooden electricity pole sizes are the first decision behind both the safety and the cost of a line. The question we hear most often with wooden pole orders is whether the length is enough. Yet a pole is defined by two things: its length and its class. Length is the total length of the pole, including the part that goes into the ground. Class tells how thick poles of the same length are, and so how much load they can carry.
What do H, O and A mean?
The letters give the weight class of the pole: H is light, O is medium and A is heavy. The higher the class, the larger the top and butt diameters. These diameters are not arbitrary: the taper of wooden poles is calculated according to TS EN 14229, and each class has a fixed minimum and maximum diameter.
Diameters by length and class
The table below shows the top and butt diameters in centimetres for the most requested lengths. All classes and the middle diameters are in the technical table on the product page.
| Length | Class | Top diameter (cm) | Butt diameter (cm) |
|---|---|---|---|
| 9 m | 9-H | 12–14 | 18–20 |
| 9 m | 9-O | 15–17 | 21–23 |
| 9 m | 9-A | 18–20 | 24–26 |
| 10 m | 10-H | 12–14 | 19–21 |
| 10 m | 10-O | 15–17 | 22–24 |
| 10 m | 10-A | 18–20 | 25–27 |
| 12 m | 12-H | 13–15 | 21–23 |
| 12 m | 12-O | 16–18 | 24–26 |
| 12 m | 12-A | 19–21 | 27–29 |
Which class for which line?
As a general guide, the light class suits distribution lines with a small conductor load and telephone lines; the medium class suits standard power distribution lines; the heavy class is chosen where the pole carries more pull, such as corner, branch and tension points. The line's design makes the final choice; if it names no class, just tell us the type of line.
What to consider when choosing the length
- The part of the pole below ground is included in the total length; softer ground needs a deeper setting.
- Obstacles and road crossings along the route set the required clearance above ground.
- One line may use several lengths; corner and crossing points may need a longer pole.
What we need for an order
Length, class, quantity and delivery place help us prepare a quote quickly. If you are not sure about the class, write the type of line and where the poles will stand in the quote form, and we will choose the class together. For telephone and wire lines, see also the impregnated telephone pole.