If you’ve ever received engineering drawings that reference an “Importance Level” and wondered exactly what that means for your project, you’re not alone. It’s one of those terms that gets used often in specifications but rarely explained clearly. And it matters more than most people realise.
Pole importance levels are a formal part of how Australian Standards classify the structural risk of poles and other structures. The level assigned to a pole shapes everything from wind loading calculations to foundation depth to how much weld testing is required. Get it wrong in either direction and you’re either over-engineering unnecessarily or, more seriously, exposing people and property to genuine risk.
What Are Pole Importance Levels?
Under Australian Standards AS/NZS 1170, every structure, including poles, is assigned one of four importance levels. The classification reflects the consequences of building failure, not how tall or heavy the pole is.
The key question is: if this pole were to fail, what’s the worst that could happen?
The answer to that question determines the importance level, which then drives the structural design actions the pole must be capable of resisting, including wind loading, seismic event loads and durability requirements.
The Four Importance Levels
| Importance Level | General Description | Typical Examples |
| IL1 | Low degree of hazard | Isolated farm buildings, rural access poles, structures presenting low hazard to human life |
| IL2 | Ordinary level (default) | Street-lighting poles, CCTV poles, signage structures in suburban areas |
| IL3 | High consequence | Primary schools, secondary schools, transport hubs, sports precincts, public utilities |
| IL4 | Post-disaster recovery | Emergency communications poles, hospitals designated to remain operational, hazardous facilities |
Importance Level 1 (IL1) covers structures where building failure poses a very low hazard to human life or other property. Think of an isolated pole on a rural property or farm buildings well away from public roads and property boundaries. Collapse would be unfortunate, but the environmental consequences and risk to people are minimal.
Importance Level 2 (IL2) is the ordinary level and serves as the baseline for most projects. The majority of streetlighting poles, CCTV poles and general utility infrastructure falls here. It’s the default unless there’s a specific reason to move up or down.
Importance Level 3 (IL3) applies where failure would carry considerable economic consequences or where a large number of people could be affected. A pole at a primary school, secondary school, major transport hub or sports precinct sits in this category. So do poles supporting critical infrastructure for public utilities like water treatment facilities. The occupant load is greater, the risk is higher, and the design must reflect that.
Importance Level 4 (IL4) is reserved for essential facilities that must remain operational after a catastrophic event, such as a cyclone or seismic event. Communications monopoles supporting emergency services, poles within or adjacent to hospitals, and structures near facilities storing hazardous materials all fall into this group. The point of Importance Level 4 is post-disaster recovery, keeping essential services running when communities need them most.
Deciding the Right Level for Your Project
The importance level for a pole isn’t something a supplier nominates. It’s determined by the project’s building certifier and engineering team. That said, understanding the factors at play helps everyone on the project team have more informed conversations.
The main considerations are:
- Occupant load and user density near the pole. A playground has a much higher occupant load than a remote access track.
- The function of the supported service. General area lighting is one thing; an emergency paging antenna is quite another.
- Proximity to public roads and property boundaries. The fall zone matters.
- Wind region and terrain category. These don’t change the importance level itself, but they interact directly with it when calculating design loads. A pole in a Pilbara town in Wind Region D faces very different conditions to one in a Perth coastal suburb in Wind Region B.
- Community reliance. If a regional town has only one hospital and you’re installing poles on that site, the classification is likely IL4.
It’s also worth noting that the same hospital campus can contain poles at different importance levels, depending on the specific structure and its role within the facility.
Why Getting It Right Matters
There’s a practical tension that project teams face regularly. A higher importance level means heavier-duty structural provisions, larger foundations, more rigorous testing of cold-formed steel structures and, in some cases, increased galvanising thickness. All of that affects your budget and lead time.
On the other hand, selecting an importance level that’s too low creates real liability. If a pole fails and it was underspecified for its environment or occupant load, the consequences, legally and physically, can be severe.
The growth in community sports lighting upgrades is a good example of where this tension plays out. Engineering consultants are increasingly being asked to weigh up IL2 against IL3, balancing crowd safety at a well-used community oval with the cost of heavier pole sections and deeper footings. There’s no single right answer, but the decision needs to be documented and justified.
Similarly, hinged poles used in maintenance programmes still need to meet their nominated importance level, regardless of how they’re accessed. The maintenance method doesn’t reduce the structural requirement.
Design documentation submitted for approval must state the importance level. Certifiers use it to verify compliance with AS/NZS 1170.2 and the NCC’s structural provisions. Without it, drawings can’t be approved.
Getting Compliant Poles, Without the Delay
G&S Industries has been engineering galvanised steel poles designed to AS/NZS 1170 for more than 55 years. Our in-house engineering and drafting team can prepare pole schedules and supporting documentation that clearly state the nominated importance level, making the certifier’s job straightforward and keeping your project moving.
Some regional councils now require suppliers to document the importance level directly in tender responses. We’re well-practised at providing that paperwork quickly, whether you’re specifying poles for a coastal Perth suburb or a remote Pilbara site.
If you’re working on a project and need guidance on the right importance level classification for your poles, contact our team and we’ll work through it with you.
Frequently Asked Questions
No. Cyclone resistance is primarily driven by your wind region and terrain category. A pole in Wind Region D (cyclonic) can be engineered to IL2 if the consequences of failure are ordinary. Importance Level 4 is about post-disaster functionality, meaning the pole must keep working after an extreme event, not just survive it.
Generally, no. The structural provisions for IL3 are embedded in the original design, including wall thickness, foundation sizing and weld testing requirements. In most cases, meeting a higher importance level requires a new pole engineered to those specific design actions.
Compliant documentation typically includes engineering drawings that reference the AS/NZS 1170 series, a pole schedule noting the nominated importance level, material certifications and, where required, weld inspection records. Our team provides this as part of our standard supply process.