Explosive Classes Explained: Understanding 1.1 to 1.6 Signs
Introduction
Explosives are classified into six subclasses — Class 1.1 through to Class 1.6 — under the UN dangerous goods system. Each class describes a different type of explosive risk, from full-scale detonation to minor popping hazards.
In New Zealand and Australia, compliance is essential under NZS/AS 1319:1994 and the Land Transport Rule: Dangerous Goods 2005. Having the correct explosive hazard sign in place ensures your workplace, transport, and storage facilities stay safe and legally compliant.
👉 For more details, see WorkSafe NZ – Hazardous Substances Signage
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The Explosive Subclasses
🔸 Class 1.1 – Mass Explosion Hazard
Class 1.1 explosives can detonate all at once, causing a mass explosion.
Examples: TNT, dynamite, blasting gelignite.
Where used: Mines, quarries, blasting operations.
Need this sign? Get our Class 1.1 Explosive Sign
Sign requirement: Clearly displayed on transport vehicles, magazines, and storage areas.
🔸 Class 1.2 – Projection Hazard (No Mass Explosion)
These explosives do not detonate en masse but can throw off dangerous projectiles.
Examples: Certain military munitions, some types of fireworks.
Where used: Defence storage and transport.
Sign requirement: Vehicles, containers, and secure sites.
Need this sign? Get our Class 1.2 Explosive Sign
🔸 Class 1.3 – Fire Hazard with Minor Blast/Projection
Explosives that pose a fire hazard, sometimes with smaller blast or projection effects.
Examples: Propellants, signal flares.
Where used: Transport, shipping containers, and warehouses.
Sign requirement: Placards on storage sites and transport vehicles.
Need this sign? Get our Class 1.3 Explosive Sign
🔸 Class 1.4 – Minor Explosion Hazard
Explosives with a limited hazard, often packaged to minimise risk.
Examples: Fireworks, small arms ammunition.
Where used: Retail fireworks, small-scale transport.
Sign requirement: Labelling of cartons, pallets, and retail storage areas.
Need this sign? Get our Class 1.4 Explosive Sign
🔸 Class 1.5 – Very Insensitive Explosives (Mass Hazard)
Class 1.5 explosives are mass explosion hazards but are insensitive, meaning they’re unlikely to detonate under normal handling.
Examples: ANFO (Ammonium Nitrate Fuel Oil).
Where used: Mining, blasting operations.
Sign requirement: Storage facilities and transport vehicles carrying bulk blasting agents.
Need this sign? Get our Class 1.5 Explosive Sign
🔸 Class 1.6 – Extremely Insensitive Explosives (No Mass Hazard)
These are the safest explosives — very insensitive, and unlikely to detonate except under exceptional conditions.
Examples: Certain military-grade insensitive munitions.
Where used: Specialist defence and research sectors.
Sign requirement: Vehicles and depots handling Class 1.6 explosives.
Need this sign? Get our Class 1.6 Explosive Sign
Size and Placement Rules
Transport Placards: Must be at least 250 mm per side.
Packages/Containers: 120 mm signs are suitable.
Warehouses/Depots: Larger 400 mm, 600 mm, or 800 mm signs provide better visibility.
Placement matters — signs must be easy to read, not obstructed, and positioned at entrances or hazard points.
👉 See UN Globally Harmonized System (GHS)
for more details.
Choosing the Right Material
Adhesive Vinyl (laminated) → Durable, long-term indoor/outdoor use.
PVC Panel → Medium-term, flat installations.
Corflute → Temporary or short-term applications.
ACM Panel → Strong, long-lasting outdoor solution.
Why Explosive Signs Matter
Protect workers, contractors, and emergency responders.
Ensure compliance with WorkSafe NZ, the HSNO Act, and NZ Transport Authority rules.
Reduce legal and insurance risks.
Promote clear communication of hazards at a glance.
👉 Need compliant explosive signs? Browse our full range of Class 1 Explosive Signs
— from Class 1.1 through to Class 1.6. All signs are designed and manufactured in New Zealand, meeting both NZ and AU standards.
“Whether it’s a polite pop or the kind of bang that rattles windows across town, there’s a sign for every explosive hazard. Stay safe, stay compliant, and leave the fireworks for New Year’s Eve.”
FAQ
Q1: What are the six explosive classes?
The six explosive subclasses (1.1–1.6) cover different hazards: mass explosion, projection, fire, minor hazards, insensitive explosives, and extremely insensitive explosives.
Q2: What size explosive signs are required for transport in NZ?
For transport placards, the minimum size is 250 mm per side. Smaller signs (120 mm) can be used on packages, while larger signs are better for warehouses and outdoor storage.
Q3: Do explosive signs need to comply with Australian standards too?
Yes — all our signs meet NZS/AS 1319:1994 and align with UN GHS standards, making them suitable for both New Zealand and Australia.
