Preferred sizes of poles (according to BS 1990: 1 1984)
Straightness
- Sweep or crook shall be permitted to the extent that a straight line from the centre of the top to the centre of the pole 1,5 m from the butt remains within the pole
Slope of grain
- Spiral grain shall not exceed a slope of 1 in 6 (180°)
Moisture content
- Moisture content prior to treatment not more than 28%
Preservation
- Average net retention of coal tar creosote type 2 – 115 kg/m3
- Sapwood penetration with preservative contains copper salts (Wolmanit CX8 or Tanalith E) – 6 kg/m3 (or different agreed with client)
Timbers
- Scots pine (Redwood) – Pinus sylvestries
- European spruce – Picea abies
Table 1 – Preferred sizes of poles
| | Light poles | Medium poles |
Nominal
lenght* | Diameter
at top | Minimum
diameter at 1,5 m
from butt end | Diameter
at top | Minimum
diameter at 1,5 m
from butt end |
min.
| max.
| | min.
| max.
| |
m
| mm
| mm
| mm
| mm
| mm | mm
|
8
8.5
9
| 125
125
125
| 150
150
150
| 170
180
180
| 145
150
150
| 180
180
180
| 210
215
220
|
NOTE: - Maximum top diameters are given only to indicate the range of tapper to be expected
* Tolerance of length +/- 1% |
Table 2 – Ultimate loads for unstayed poles of redwood (pine)
| | Light poles | Medium poles |
Nominal
lenght | Minimum
diameter at 1,5 m
from butt end | Ultimate loads at 0,6 m from top
| Load per millimetre of deflection at point of application of load
| Minimum
diameter at 1,5 m
from butt end | Ultimate loads at 0,6 m from top
| Load per millimetre of deflection at point of application of load
|
| m | mm
| kN
| N
| mm
| kN
| N
|
8
8.5
9 | 170
180
180
| 4.40
4.81
4.46 | 4.8
4.5
3.6
| 210
215
220
| 8.29
8.20
8.15
| 10.5
9.1
7.8
|
