Protection & Control calculator
Arc Flash Incident Energy Scaling Calculator
Scale a validated incident-energy result when only arc duration changes. This comparison tool does not perform a complete IEEE 1584 calculation.
ProtectionBasis: Duration scaling from an existing validated study
Results
- Enter values to calculate
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How to use this calculator
Arc-flash incident energy describes thermal exposure at a stated distance and duration. This calculator answers one narrow question: how does an already established energy result change if duration alone changes? It needs a reference result from a validated study.
A complete IEEE 1584-2018 workflow selects the applicable three-phase AC model, determines arcing current from the equipment geometry and fault level, obtains protective-device clearing time, calculates incident energy and boundary, and repeats the relevant evaluation with reduced arcing current. Lower arcing current can cause slower protection and greater energy. The highest applicable result must be considered.
The standard covers three-phase AC systems from 208 V to 15 kV subject to its model limits. Single-phase and DC systems require other methods. Arc-flash boundary is an energy contour, not a universal safe-work distance or an arc-blast boundary.
Formula
Enew = Ereference × tnew/treference
This relation applies only when the incident-energy model, arcing current, voltage, conductor gap, enclosure, electrode configuration and working distance are unchanged. It compares duration at one working distance; it is not the complete IEEE 1584 empirical model.
1 cal/cm² = 4.184 J/cm². The commonly used 1.2 cal/cm² boundary threshold is approximately 5.02 J/cm²; it does not account for every arc hazard.
Worked example
Suppose a validated study gives 4 cal/cm² at 455 mm for 0.10 s. At unchanged arcing current and geometry, a confirmed duration of 0.05 s gives 2 cal/cm². This example verifies time scaling only; it does not determine arcing current, boundary or protective-device performance.
Assumptions and standards
- Use only for duration comparisons at unchanged study conditions. Do not substitute bolted fault current for arcing current.
- No IEEE coefficient engine, electrode-selection model, enclosure correction, boundary calculation or PPE selection is included.
- A complete implementation requires the adopted IEEE 1584 edition, applicable corrections and benchmark validation.
Calculation model checked: November 4, 2026
Frequently asked questions
Is this a full IEEE 1584 calculator?
No. It rescales a known incident-energy result when only arc duration changes. It does not calculate arcing current or arc-flash boundary.
Can lower fault current increase incident energy?
Yes. Lower arcing current may delay operation of a protective device. The longer duration can outweigh the reduced current, which is why both applicable current cases need evaluation.
Can I use these results for final design?
Use them for preliminary design and checking. Final designs must be verified by a qualified engineer against the code edition and standards adopted where the work is installed.
Is my data sent anywhere?
No. Every calculation runs in your browser. Nothing you type is uploaded or stored on our servers.
References and further reading
Power system calculations: formulas and model guide