Skip to content 
For HDG street light poles, don’t ask “galvanized or not.” Specify one standard (ISO 1461 or ASTM A123), set a project coating thickness target (µm) for the environment, and require site acceptance inspection (lot definition, sampling, multi-point magnetic gauge readings on shaft + base plate, and documented repairs for any post-work damage). This prevents premature rust in coastal or industrial projects.
Hot-dip galvanizing (HDG) protects steel street light poles by forming a zinc–iron alloy coating in molten zinc (~450°C). For EPC and municipal projects, the decision is not “galvanized or not” — it’s which standard (ISO 1461 / ASTM A123), what coating thickness acceptance you require, and how you verify acceptance on delivery, especially in coastal or industrial environments.
Rain, humidity, and pollution attack poles every day. If steel is not properly protected, a pole that looks strong at installation can become a safety risk within a few years.
This guide is written for municipal engineers, EPC contractors, and distributors who need to:
- avoid premature rust and site complaints
- understand galvanizing standards and coating thickness acceptance
- write clear specifications so suppliers cannot cut corners
We focus less on schoolbook definitions and more on what you should actually specify and check during tendering and site acceptance.
Update note: Maintained using common tender clauses, incoming inspection checklists, and recurring failure modes observed in project deliveries (coastal corrosion, thin edges, post-work damage).
Get the Galvanizing Inspection Checklist (EPC Only, 12–24h)
If you are preparing a tender/BOQ or receiving poles on site, send us:
- Project location + environment (inland / coastal / industrial)
- Pole height range + wall thickness range (if known)
- Any tender clause about galvanizing / coating standard
We’ll reply within 12–24 working hours with:
- Recommended spec wording (ISO 1461 / ASTM A123)
- Suggested project target thickness direction based on environment (µm)
- An incoming inspection plan (lot definition, sampling, reference areas, acceptance notes)
Request the checklist → Contact Sunlurio
No retail / household inquiries.
EPC Quick Checklist: What to Specify (Copy/Paste)
Use this block in your BOQ / technical specification to stop corner-cutting:
- Galvanizing standard: ISO 1461 or ASTM A123 (state one clearly)
- Process: hot-dip galvanized after fabrication (shaft + base plate)
- Inside & outside: require galvanizing inside and outside (important for condensation corrosion)
- Thickness acceptance: meet the selected standard’s acceptance method (by steel thickness category; avoid “one reading” acceptance)
- Sampling: define inspection lot and sampling size in your QA/ITP plan; require lot-based reporting
- Inspection method: calibrated magnetic gauge readings at multiple points (shaft + base plate) + supplier report with lot ID
- No post-galvanizing fabrication: avoid welding/cutting/drilling after HDG; if unavoidable, repair using an approved zinc-rich method and document touch-up locations
- After-work repairs: define an approved zinc-rich touch-up method for any handling or site drilling/cutting
ISO 1461 vs ASTM A123 (60-Second Decision Guide)
Both standards are widely used. The key is to select one and write acceptance clearly.
| Item | ISO 1461 | ASTM A123 |
|---|---|---|
| Common usage | Global / EU tenders | US-style specs & projects |
| Best for | Fabricated articles with clear acceptance logic | General iron/steel products with standardized acceptance approach |
| Tender risk if unclear | Supplier cherry-picks easier interpretation | Same — ambiguity creates loopholes |
| Rule | Choose one standard and define lot + inspection + records | Choose one standard and define lot + inspection + records |
Rule: Don’t mix standards loosely. Ambiguous “HDG only” clauses invite corner-cutting.
1) What Is a Hot-Dip Galvanized Street Light Pole?
A galvanized street light pole is a steel pole coated with zinc to protect it from corrosion.
The most reliable method for outdoor lighting structures is hot-dip galvanizing:
- The pole is fabricated and welded.
- It is chemically cleaned (degreasing, pickling) to remove oil, rust, and mill scale.
- The pole is dipped into molten zinc at about 450°C.
- A metallurgical bond forms between zinc and steel — zinc–iron alloy layers grow into the steel surface.
This is typically stronger and longer-lasting than paint alone.
Other methods you might see:
- Electro-galvanizing: thin zinc layer applied with electric current (common for small parts, not ideal as primary protection for poles).
- Zinc spraying / “cold galvanizing” paint: zinc-rich coatings used mainly for touch-up, not as primary corrosion protection.
For street lighting structures—especially 8–15 m road poles and high masts—serious projects usually require batch hot-dip galvanizing to recognized standards.
2) Why Galvanizing Matters for Street Light Poles (Project View)
Untreated or poorly protected steel:
- rusts quickly in coastal, industrial, or humid environments
- loses wall thickness over time
- can become a structural and public safety risk, especially under wind load
Proper HDG provides:
- Corrosion resistance (sacrificial protection + protection near small scratches)
- Extended service life (environment- and thickness-dependent)
- Structural safety (fewer hidden weak spots at welds and base plate)
- Lower lifetime cost (less repainting, fewer emergency replacements)
Why corrosion spec impacts roadway lighting performance (not just appearance)
Roadway lighting is designed and checked using maintained lighting performance targets (average maintained illuminance, minimum points, and uniformity). In real projects, pole corrosion can trigger:
- pole leaning or base plate distortion
- anchor bolt rework
- emergency replacement outages
This directly breaks the maintained lighting performance the roadway plan is built on. A clear HDG specification helps keep the lighting system compliant over its design life.
3) Standards, Coating Thickness, and Acceptance (What Tenders Should Actually Say)
Not all galvanized poles are the same. The standard + acceptance logic + inspection discipline you specify will directly influence durability.
Common international standards:
- ASTM A123 – Hot-dip galvanizing of iron and steel products
- ASTM A153 – Hot-dip galvanizing of steel hardware and fasteners
- ISO 1461 – Hot-dip galvanized coatings on fabricated iron and steel articles
- BS EN ISO 1461 – UK/EU implementation of ISO 1461
3.1 ISO 1461 minimum coating thickness (fabricated articles)
If you specify ISO 1461, acceptance is based on minimum mean thickness and minimum local thickness by steel section thickness.
| Steel thickness t (mm) | Minimum local thickness (µm) | Minimum mean thickness (µm) |
|---|---|---|
| t > 6 | 70 | 85 |
| 3 < t ≤ 6 | 55 | 70 |
| 1.5 ≤ t ≤ 3 | 45 | 55 |
| t < 1.5 | 35 | 45 |
Important: If the pole includes different steel thickness ranges (e.g., shaft vs base plate), treat each thickness range separately.
3.2 Project targets vs standard minimums (how to write “thickness direction” correctly)
Tenders often add a “project target thickness direction” above standard minimums, especially in aggressive environments.
Typical project targets (above minimums, not universal):
- Inland / normal atmosphere: ~70–85 µm (common target direction for typical pole wall thickness ranges)
- Coastal / industrial / high-pollution: ~85–100+ µm (often specified to extend service life)
Important: Final acceptance must still follow the selected standard’s acceptance method and steel thickness category. Do not rely on a supplier’s “typical thickness” claim.
3.3 What to ask your supplier (minimum)
Don’t ask only “Are they galvanized?” Ask for:
- Which standard? (ASTM A123 / ISO 1461 / BS EN ISO 1461)
- Project target thickness direction (µm or g/m²)
- Thickness test report (multi-point magnetic gauge readings)
- Inside galvanizing confirmation (critical for condensation corrosion)
- Lot ID and traceability (so site acceptance is auditable)
Tender line that filters out many suppliers:
“Poles shall be hot-dip galvanized inside and outside to ISO 1461 (or ASTM A123), after fabrication. Coating thickness acceptance shall follow the selected standard. Supplier shall provide lot-based thickness reports with multi-point gauge readings on shaft and base plate.”
3.4 Corner-cutting watch list (how to spot it fast)
- “Galvanized” but no standard stated (ISO 1461 / ASTM A123 missing)
- No lot-based thickness report (only verbal confirmation)
- Readings only on easy shaft areas (no base plate verification)
- No inside galvanizing confirmation for closed poles (condensation risk)
- Post-galvanizing cutting/drilling with no documented repair
- Thin coating at edges/corners due to poor preparation or handling
3.5 Case photo suggestion: early rust vs proper HDG (high-impact evidence)
Add one comparison image to improve trust and speed up decision-making:
- left: early rust around base plate / service door area (vague spec, weak inspection)
- right: intact HDG surface after service period (clear spec, documented acceptance)
Recommended caption: Early Rust vs Proper HDG: What Happens When the Spec Is Vague
Recommended alt text: Comparison of early rust on low-quality galvanized pole vs intact HDG pole with documented ISO 1461 / ASTM A123 inspection
Special note: thermally cut edges and post-work risk
Poles often include thermally cut parts (base plates, openings, stiffeners). These areas can be harder to galvanize consistently and are common failure start points if edges are sharp or post-work is done after HDG.
Procurement control:
- Require edge preparation and avoid sharp corners where possible
- Avoid post-galvanizing fabrication; if unavoidable, require approved repair + records
- Add a specific inspection note for cut edges and base plate corners
4) Galvanized vs Non-Galvanized Poles (Paint Only)
| Feature | Hot-Dip Galvanized Pole | Non-Galvanized / Painted Only Pole |
|---|---|---|
| Corrosion resistance | High – zinc sacrificial protection | Low – paint can crack/peel, steel rusts directly |
| Inner surface protection | Yes (if HDG inside/outside) | Usually no – inside rust from condensation |
| Maintenance requirements | Low – periodic inspection | High – frequent repainting/repairs |
| Typical service life | Long (environment-dependent) | Shorter in harsh climates |
| Initial cost | Often higher | Lower, but often at cost of durability |
| Lifetime cost | Often lower over design life | Higher due to repainting + early replacement |
| Acceptance clarity | Clear (standard + acceptance + inspection records) | Often vague (“painted”) |
| Recommended use | Roads, highways, coastal & industrial sites | Temporary / short-term outdoor / indoor |
For municipalities and EPCs, what matters is total cost over the design life, not day-one price.
5) Where Hot-Dip Galvanized Poles Are Most Commonly Used
- Coastal cities (salt air)
- Urban highways and expressways (pollution)
- Bridges/flyovers (maintenance difficult)
- Industrial zones (corrosive atmosphere)
- Parks/plazas/pathways (humidity/irrigation)
6) Common Misconceptions About Galvanized Poles
“Galvanizing is just painting with silver color”
False. Hot-dip galvanizing forms a metallurgical bond (zinc–iron layers), not a simple topcoat.
“Galvanizing is too expensive”
Upfront can be higher, but design-life cost is often lower due to reduced repainting and fewer replacements.
“If it’s galvanized, it will never rust”
Even HDG can fail early if thickness is too low, if post-work is not repaired, or in very aggressive environments. The goal is predictable corrosion protection over the design life.
7) How to Specify Galvanized Street Light Poles in Your Project
7.1 Basic elements to include
- Pole height & type (8 m single arm / 10 m double arm / 12 m highway, etc.)
- Steel grade (Q235/Q355 or S235/S355)
- Galvanizing standard + acceptance approach (ISO 1461 or ASTM A123)
- Inside & outside galvanizing after fabrication
- Accessories protected: base plates, brackets, anchor bolt kits (as applicable)
7.2 Optional but useful
- Environment category (inland/coastal/industrial)
- Duplex finish (HDG first → surface prep → powder coat/paint) if required
8) Incoming Inspection Workflow (Site Acceptance)
A repeatable workflow prevents “subjective” acceptance disputes.
Step 1 — Define the inspection lot
Group poles by the same specification and batch/lot identification. Supplier should label lots.
Step 2 — Select the sampling size (ISO 1461 control sample guide)
If you are following ISO 1461 sampling guidance, a common control sample size by lot is:
| Number of articles in the lot | Minimum number of articles in the control sample |
|---|---|
| 1–3 | all |
| 4–500 | 3 |
| 501–1200 | 5 |
| 1201–3200 | 8 |
| 3201–10,000 | 13 |
| >10,000 | 20 |
Step 3 — Define measurement reference areas
Measure at consistent reference zones:
- shaft: lower / middle / upper sections (avoid edges, holes, and discontinuities)
- base plate: flat areas (avoid sharp corners)
Step 4 — Take multi-point magnetic gauge readings
Use a calibrated magnetic thickness gauge. Record readings with location notes.
Step 5 — Compare against the selected standard acceptance
Acceptance is based on the selected standard and steel thickness category — not a supplier’s “typical thickness”.
Step 6 — Handle post-work and damage
No cutting/welding/drilling after HDG unless:
- an approved zinc-rich repair system is applied
- repair locations are documented for acceptance
What to request from suppliers (evidence package)
To support acceptance on site (and avoid arguments later), request an evidence pack tied to a lot ID:
- Galvanizing declaration: the applied standard (ISO 1461 or ASTM A123) and confirmation that galvanizing is done after fabrication
- Lot identification & traceability: lot number, production date, pole IDs/marking, and quantity per lot
- Coating thickness report (magnetic gauge):
- instrument model + calibration status/date
- measurement locations and number of readings
- results reported separately for shaft and base plate
- Inside galvanizing confirmation (for closed sections): statement + photos if available
- Repair/touch-up record: any post-work or handling damage repairs with:
- repair method (zinc-rich system)
- repair locations (photo-marked)
- verification notes (dry film thickness / visual acceptance as applicable)
- Visual inspection record: note any runs, bare spots, dross, sharp edges, or blocked holes (and how they were corrected)
If the supplier cannot provide lot-based records, treat it as a tender risk.
Pass/Fail acceptance notes (simple and defensible)
Use a consistent rule in your incoming inspection plan:
- Acceptance follows the selected standard (ISO 1461 or ASTM A123), including how average/local readings are evaluated by steel thickness category.
- If the pole contains different thickness zones (shaft vs base plate), verify and record them separately.
- Do not accept “single-point” statements like “average 80 µm” without lot ID, sampling, and multi-point logs.
- If any post-galvanizing drilling/cutting happens on site, require:
- an approved zinc-rich repair method
- a repair log with photos/locations
- a final sign-off note in the acceptance record
Common rejection triggers (fast field checks)
Reject or quarantine a lot until clarified if you observe:
- no stated standard (ISO 1461 / ASTM A123 not declared)
- no lot ID or traceability
- missing thickness report or no gauge calibration reference
- thickness readings only taken on “easy” shaft areas (base plate ignored)
- bare spots or severe roughness around holes, edges, or base plate corners
- post-work damage with no documented repair method and locations
9) Copy/Paste Tender Clause (Project-Ready)
Use this clause to prevent ambiguity:
“Street light poles shall be hot-dip galvanized after fabrication, inside and outside, to ISO 1461 (or ASTM A123) as stated in this BOQ. Coating thickness acceptance shall follow the selected standard’s acceptance method. Supplier shall provide lot-based coating thickness reports with multi-point magnetic gauge readings on the pole shaft and base plate, including traceability (lot ID) and repair documentation for any post-work damage.”
10) Final Takeaway for EPC & Municipal Teams
If you want HDG poles to survive coastal or industrial exposure without early rust complaints, control three things:
1) One standard (ISO 1461 or ASTM A123)
2) A project thickness target direction (µm) suited to the environment
3) A defensible site acceptance workflow (lot definition, sampling, multi-point readings, and documented repairs)
Get the Inspection Checklist (EPC Only)
Preparing a tender or receiving poles on site?
Send us:
- location + environment (inland / coastal / industrial)
- pole height range + wall thickness range (if known)
- your tender clause (if available)
Request the checklist → Contact Sunlurio
No retail / household inquiries.
FAQ
ISO 1461 vs ASTM A123 — which should I use for street light poles?
Choose the standard commonly used by the client/region (ISO 1461 for many global/EU-style tenders; ASTM A123 for US-style specs). The key is to select one and define acceptance + inspection clearly.
What coating thickness (µm) should I require for coastal environments?
Define a project target direction (often ~85–100+ µm for aggressive atmospheres), then accept based on the selected standard’s method by steel thickness category.
How do I define an inspection lot and sampling plan?
Group poles by the same specification and supplier batch/lot ID, then sample per your QA/ITP plan and record results by lot.
Where should coating thickness be measured on a pole?
Measure multiple points on both the shaft and base plate (flat areas), and keep records of locations and readings.
How should post-galvanizing drilling/cutting be repaired?
Avoid it where possible. If unavoidable, repair using an approved zinc-rich method and document repair locations with photos and acceptance notes.
