Arc Flash Calculator
Calculate incident energy, arc flash boundaries, and required PPE categories for electrical safety. Based on NFPA 70E and IEEE 1584 standards.
Use Calculator in AppWhat is Arc Flash?
Arc flash is a dangerous electrical explosion that occurs when current flows through air between conductors or from a conductor to ground. The resulting arc can produce temperatures up to 35,000°F (four times hotter than the sun's surface), along with intense light, sound pressure, and shrapnel.
Arc flash hazard analysis is required by OSHA and NFPA 70E to protect workers from these severe hazards. The analysis determines the incident energy at the working distance and the appropriate personal protective equipment (PPE) required.
NFPA 70E PPE Categories
| PPE Category | Incident Energy Range | Min Arc Rating | Required PPE |
|---|---|---|---|
| Category 1 | 1.2 - 4 cal/cm² | 4 cal/cm² | Arc-rated shirt, pants, face shield |
| Category 2 | 4 - 8 cal/cm² | 8 cal/cm² | Arc-rated shirt, pants, flash suit hood |
| Category 3 | 8 - 25 cal/cm² | 25 cal/cm² | Arc flash suit, hood, gloves |
| Category 4 | 25 - 40 cal/cm² | 40 cal/cm² | Multi-layer flash suit, full PPE |
Work is NOT permitted where incident energy exceeds 40 cal/cm² without additional protection measures.
Arc Flash Boundary
The arc flash boundary is the distance from the arc source at which the incident energy equals 1.2 cal/cm² - the energy level that can cause a curable second-degree burn. All personnel within this boundary must wear appropriate PPE.
Approach Boundaries (NFPA 70E)
- Arc Flash Boundary: Distance where incident energy = 1.2 cal/cm²
- Limited Approach: Qualified persons only beyond this point
- Restricted Approach: Shock hazard exists - PPE required
- Prohibited Approach: Same as direct contact
Key Arc Flash Variables
Available Fault Current
The maximum short-circuit current available at the equipment, measured in kA.
Clearing Time
Time for protective device to clear the fault, in seconds or cycles.
Working Distance
Distance from arc source to worker's face/body, typically 18" for panels.
System Voltage
Nominal system voltage affects arc energy and calculation method.
IEEE 1584 Calculation Method
The IEEE 1584-2018 standard provides empirical equations for calculating incident energy based on extensive testing. The calculation involves:
- Arcing Current Calculation: Determine arc current based on available fault current
- Incident Energy Calculation: Calculate energy at working distance
- Arc Flash Boundary: Solve for distance where E = 1.2 cal/cm²
IEEE 1584-2018 provides different equations for systems under 600V, 600V-15kV, and electrode configurations (VCB, VCBB, HCB, VOA, HOA).
Typical Working Distances
| Equipment Type | Working Distance |
|---|---|
| Panelboards (LV) | 18 inches (455 mm) |
| MCC / Switchgear (LV) | 24 inches (610 mm) |
| Switchgear (MV) | 36 inches (914 mm) |
| Cable terminations / splices | 18 inches (455 mm) |
Stay Safe with Ampora Arc Flash Calculator
Quick arc flash calculations on the job. Enter system parameters and get instant incident energy, PPE category, and arc flash boundary results.
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