(And Why It’s One of the Most Misunderstood Electrical Hazards)
Arc flash is often talked about, rarely understood, and frequently underestimated.
Many serious electrical incidents don’t occur because workers are careless — they occur because arc flash behaves very differently to what people expect. It doesn’t require high voltage, it gives no warning, and by the time protection devices operate, the damage is often already done.
This article explains how arc flash actually occurs, what causes it in real workplaces, how severity is determined, and why prevention, PPE, and rescue planning must be considered together — particularly under Australian conditions and standards.
What Is an Arc Flash
An arc flash is a sudden release of energy caused by an electrical arc. That arc forms when electricity jumps through the air between conductors or from a conductor to earth.
When this happens, enormous energy is released in milliseconds, producing:
- Extreme heat – Temperatures can exceed 19,000°C
- A powerful pressure wave
- Blinding light
- Molten metal and shrapnel
- Toxic gases and smoke
Unlike electric shock, arc flash does not require direct contact. Being in close proximity to an arc flash has the potential to cause irreversible damage.
This is why Arc Flash is so dangerous — and why it is so often misunderstood.
How Arc Flash Actually Occurs
Arc Flash doesn’t “just happen.” It occurs when a specific set of conditions line up.
1. Energised Electrical Equipment
The equipment is live — often believed to be isolated, partially isolated, or “safe enough”.
This commonly includes:
- Switchboards and control panels
- MCCs
- Substations
- EV charging and power distribution infrastructure
2. Breakdown of Insulation or Air Gap
Electricity is normally contained within conductors and insulation. Arc Flash begins when that control is lost.
This breakdown can be caused by:
- Dropped tools
- Degraded insulation
- Moisture, dust, or contamination
- Corrosion or ageing components
- Incorrect clearances
Air becomes the conductor.
3. Formation of an Electrical Arc
Once the air ionises, current flows violently through it.
Temperatures can exceed 19,000°C, instantly vaporising copper and steel. Vapourised metal expands rapidly, creating an explosive force.
4. Energy Release Before Protection Operates
Protection devices do operate — but not instantly.
In many cases:
- Arc Flash energy is released before the breaker clears the fault
- Injury occurs within milliseconds
- PPE becomes the final line of defence, not the first
Arc Flash vs Arc Blast: What’s the Difference?
Arc Flash and arc blast are often grouped together — but they describe different injury mechanisms, even though they usually occur at the same time.
Arc Flash refers to the intense thermal energy released by the arc. This heat can:
- Cause severe burns
- Ignite clothing
- Melt metal components
- Damage eyes and airways
Arc Blast refers to the pressure wave and physical explosion created by the rapid expansion of vapourised metal and heated air. This can:
- Throw workers across rooms
- Rupture eardrums
- Cause blunt-force trauma
- Turn metal into high-velocity shrapnel
In real incidents, workers are often injured by both — heat first, then blast.
Diagram credited to Brady Corporation: https://www.bradyid.com/resources/what-is-arc-flash
Arc Flash Happens Faster Than Human Reaction
To put the risk into perspective:
- Arc Flash temperatures can exceed 19,000°C
- The main energy release occurs in milliseconds
- Human reaction time is around 300–400 milliseconds
- Copper can instantly vaporise and expand up to 67,000 times its original volume
By the time a person can react, the injury has often already occurred.
Common Real-World Causes of Arc Flash
Across Australian workplaces, the same causes appear repeatedly:
- Human error (slips, dropped tools, incorrect assumptions)
- Poor isolation or verification
- Working live when it isn’t necessary
- Contamination (dust, moisture, insects)
- Incorrect PPE selection
- Rushed or non-routine tasks
- Poorly maintained or ageing equipment
Most Arc Flash incidents occur during:
- Fault finding
- Switching
- Testing
- Maintenance
- Commissioning
Often during routine work, not extreme scenarios.
What Determines How Severe an Arc Flash Will Be
Not all arc flash incidents are equal. The severity of an arc flash is determined by the incident energy released — an engineering-based calculation that considers several factors acting together.
Available Arc Fault Current
Arc fault current influences how much energy can be released, but it does not act alone. In some systems, extremely high fault current can actually reduce exposure if protection clears quickly.
Duration of the Arc (Clearing Time)
How long the arc persists is one of the most critical factors. Even small increases in clearing time can dramatically increase incident energy and injury severity.
Working Distance
Incident energy decreases rapidly with distance. Small changes in how close a worker is to the arc source can significantly affect burn severity.
Equipment Enclosure and Configuration
Arc flash occurring inside switchboards, panels, or cabinets can concentrate heat and pressure, directing energy outward toward the worker and increasing blast effects.
PPE System Selection
PPE must be selected based on calculated incident energy, not voltage alone. Inadequate or mismatched PPE can fail, even on low-voltage systems.
This is why assumptions like “it’s only low voltage” are so dangerous — arc flash severity is determined by energy, not voltage.
The Myths That Get People Seriously Injured
Almost every investigation uncovers the same beliefs:
- “It’s only low voltage”
- “It was isolated”
- “It’ll trip if something goes wrong”
- “I’ve done this a hundred times”
- “I’m protected with Insulated gloves”
Arc flash does not care about experience or intention — only conditions.
Arc Flash Control Isn’t Just PPE
Best practice follows the hierarchy of control:
Elimination – de-energise wherever possible
Engineering controls – protection settings, barriers, switchgear design
Administrative controls – procedures, permits, competency-based training
PPE – arc-rated clothing, face protection, insulated gloves and tools
PPE is critical — but it is the last line of defence, not the first.
PPE’s Role: Before, During, and After an Arc Flash
PPE plays three distinct roles:
Before – supports risk control and safe work planning
During – limits burn, blast, and secondary injuries
After – enables safe and rapid rescue
Survivability often depends on what happens after the incident.
Australian Standards and Legal Expectations
Arc flash is a recognised workplace hazard in Australia.
Key standards include:
- AS/NZS 4836:2023 – Safe working on or near low-voltage electrical installations
- AS 2067 – Substations and high-voltage installations
Other standards include:
- NFPA70E – A widely adopted electrical safety standard that defines arc flash risk assessment methods and PPE requirements for electrical work.
- IEEE 1584 – The engineering standard used to calculate arc flash incident energy.
- IEC 61482 – An international standard that defines testing and performance requirements for arc-rated PPE fabrics and garments.
These standards require that:
- Arc flash risks are identified and controlled
- PPE is task-specific
- Workers are trained and competent
- Rescue procedures are planned and practised
Electrical Arc Flash: Guidance from Australian Regulators
Australian electrical safety regulators consistently reinforce that arc flash is a preventable hazard when correct controls are applied.
A safety film published by WorkSafe Queensland clearly outlines the primary control:
De-energise equipment before starting any electrical work to prevent burns, injury and death caused by an electrical arc flash.
If the job requires you to work live, control the risks and follow safe work procedures.
This guidance aligns directly with Australian standards and reflects the reality of arc flash incidents across industry:
- Arc flash events most commonly occur when work is carried out on energised equipment
- The most effective control is elimination — de-energising wherever possible
- When live work cannot be avoided, risk controls must be deliberate, documented, and enforced
The regulator’s message is clear: arc flash is not an unavoidable consequence of electrical work — it is a known, controllable risk.
Watch the Electrical Arc Flash safety film from WorkSafe Queensland:
👉 https://www.worksafe.qld.gov.au/resources/videos/films/electrical-arc-flash-film
The Key Things To Ask Your Team Today
If you work on or near energised electrical equipment, ask:
- Have our arc flash risks been assessed recently?
- Is the risk for this job site known and documented?
- Is our PPE genuinely matched to the task?
- Do we have trained LV rescue capability on site?
- Would our team know what to do in the first 30 seconds?
If the answer isn’t clear, it’s time to act.
If your team needs support selecting task-appropriate arc-rated PPE, face protection, or complete arc flash systems, you can review Volt Safety’s dedicated arc flash protection range here:
👉 https://voltsafety.com.au/product-category/arc-flash