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1. Understanding Galvanized Street Light Poles
A galvanized street light pole is made of steel and protected by a zinc coating through hot-dip galvanization. This process prevents rusting and extends service life — especially important in humid or coastal environments.
You’ll find these poles lining highways, residential streets, and ports across Africa, where heat, dust, and salt air can test even the toughest materials. In practice, hot-dip galvanization often doubles the service life compared to painted poles.
Why galvanization still matters today:
- Prevents corrosion and paint peeling
- Minimizes maintenance in public infrastructure
- Maintains clean, uniform city lighting for decades
Typical applications:
- Residential streets: 6–8 m
- Main roads: 10–12 m
- Ports & airports: 20–30 m
- Industrial zones: custom polygonal types
2. Common Sizes and Shapes of Galvanized Street Light Poles
Manufacturers typically provide conical or polygonal shapes, depending on the required look and structural load. Below are common dimensions used by EPC contractors in city lighting projects.
| Height (m / ft) | Shape Type | Typical Use | Base Diameter (mm) | Top Diameter (mm) |
|---|---|---|---|---|
| 3 m / 9.8 ft | Round / Octagonal | Gardens, pathways | 110 | 60 |
| 6 m / 19.7 ft | Conical | Residential roads | 145 | 70 |
| 8 m / 26.2 ft | Polygonal | City streets | 165 | 80 |
| 10 m / 32.8 ft | Octagonal | Secondary highways | 190 | 90 |
| 12 m / 39.4 ft | Conical | Main roads | 210 | 100 |
| 15 m / 49.2 ft | Polygonal | Industrial zones | 240 | 115 |
| 20–30 m / 65–98 ft | Custom polygonal | Stadiums, ports | 300–450 | 120–200 |
Most modern street poles are tapered, with ratios around 1:10–1:15 for visual balance and structural strength.
For urban projects, 6–10 m poles are ideal for consistent lighting, while highways often demand taller, polygonal profiles for better reach and wind resistance.
3. Material Specifications and Structural Grades
Most fabricators rely on Q235B, Q345B, or Q355 steel — each offering a balance of cost, weldability, and strength.
From experience, Q235B serves well for calm inland zones, while Q355 performs better in high-wind or coastal projects where corrosion stress is severe.
| Steel Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Best For |
|---|---|---|---|---|
| Q235B | ≥ 235 | 370–500 | 26 | Residential / inland areas |
| Q345B | ≥ 345 | 470–630 | 22 | City roads, mid-wind regions |
| Q355 | ≥ 355 | 490–620 | 20 | Coastal or industrial projects |
Typical wall thickness ranges from 2.5 mm to 30 mm, adjusted by height and local wind speed.
Poles may be welded or seamless, though welded versions are more common for cost efficiency and easier fabrication.
4. Galvanization and Surface Coating in Practice
In a typical production line, each pole is cleaned, pickled, and then dipped into molten zinc at around 450 °C. This creates a zinc-iron layer that seals even inner surfaces from oxidation.
| Process | Zinc Thickness | Standard | Finish Color |
|---|---|---|---|
| Hot-dip galvanization | 80–100 µm (3.1–3.9 mils) | ASTM A123 / GB/T 13912-2002 | Silver grey |
| Powder coating | 60–80 µm | Custom RAL colors | White / Black / Blue / Grey |
| Electrostatic paint | 50–70 µm | ISO 1461 | Decorative finishes |
In coastal or desert environments, we often specify dual coating — hot-dip zinc plus powder paint — to resist salt fog and UV degradation.
The standard galvanization for galvanized street light poles remains hot-dip coating with 80–100 µm zinc, ensuring long-term durability per ASTM A123.
5. Wind Load and Structural Performance
During design, engineers calculate wind loads to ensure stability under storm conditions.
For example, in open plains or coastal towns, poles may need to withstand gusts exceeding 160 km/h.
| Pole Height (m) | Max Wind Speed (km/h) | Wall Thickness (mm) | Design Zone |
|---|---|---|---|
| 6 | 130 | 2.5 | Urban / calm zones |
| 8 | 145 | 3.0 | Inland towns |
| 10 | 160 | 3.5–4.0 | Highways |
| 12–15 | 180 | 5–8 | Coastal areas |
Wind load formula:
F = 0.613 × V² × Cd × A
Where V is wind speed (m/s), Cd is drag coefficient, and A is projected area.
Always check local building codes — in some coastal regions, poles must handle up to 180 km/h.
6. Base Design and Arm Configurations
Most city installations use flange-mounted bases for easy maintenance and replacement.
Poles can be equipped with single, double, or triple arms, depending on road width and light coverage.
| Feature | Specification |
|---|---|
| Base Plate Thickness | 16–30 mm |
| Bolt Hole Pattern | 4–6 slotted holes |
| Anchor Bolt Diameter | M20 – M36 |
| Arm Type | Single / Double / Triple |
| Mounting Angle | 5° – 15° upward |
| Foundation Depth | 1.2 – 2.5 m (depends on soil) |
From site experience, clay soils require deeper foundations (over 2 m) to prevent gradual tilting.
In contrast, sandy soils need wider bases to spread load evenly.
7. Key Standards and Compliance
These standards ensure compatibility and consistent quality among suppliers.
For instance, ASTM A123 and GB/T 13912-2002 specify nearly equivalent zinc thickness ranges.
| Standard | Scope | Region / Organization |
|---|---|---|
| ASTM A123 | Zinc coating on steel | USA |
| GB/T 13912-2002 | Hot-dip galvanizing | China |
| ISO 1461 | General galvanization spec | International |
| EN 40 | Lighting column design | Europe |
| AWS D1.1 | Welding standard | Global |
Unlike ISO 1461, which focuses on coating durability, EN 40 emphasizes design strength and load testing — both critical for public lighting infrastructure.
8. How to Choose the Right Pole for Your Project
Choosing the correct pole height depends on road width, luminaire power, and terrain.
If the road width is under 10 m, a 6–8 m pole provides good light uniformity. For main roads or intersections, 10–12 m poles are common.
| Factor | Recommendation |
|---|---|
| Road width < 10 m | 6–8 m pole |
| 10–15 m width | 8–10 m pole |
| Highways | 10–15 m pole |
| Windy/coastal | Q345B / Q355 steel |
| Decorative zones | Add powder coating |
When budgeting, it’s wiser to invest in stronger steel grades rather than thicker coatings — the latter wears down faster under sand or salt exposure.
From experience, the best value-for-longevity balance is Q345B steel with 80–100 µm zinc.
Engineers Often Ask
Q: What is the standard galvanization thickness?
A: 80–100 µm hot-dip zinc coating (ASTM A123 / GB/T 13912).
Q: How often should galvanization be inspected?
A: Every 3–5 years, depending on humidity and proximity to the coast.
Q: What pole size suits LED street lights?
A: For a 12 m wide road, around a 10 m conical pole works well, balancing illumination and cost.
Q: What’s the most durable combination?
A: Q355 steel + hot-dip zinc + powder topcoat — ideal for high-humidity regions.
Conclusion
In the end, a well-chosen galvanized pole isn’t just about steel and zinc — it’s about keeping streets safe and bright for decades.
Field data from East African cities shows that proper galvanization can halve maintenance costs and extend service life beyond 25 years.
