An arc flash study calculates the incident energy a worker could be exposed to at each piece of equipment, sets the arc flash boundary, and identifies ways to reduce the hazard. IEEE 1584-2018 is the current calculation method; it models electrode configuration and enclosure size, so results from older studies often change when a plant is re-studied.
Key Takeaways
- Incident energy is calculated per bus, from fault level and protection clearing time.
- IEEE 1584-2018 added electrode configuration and enclosure size to the model.
- Clearing time is usually the biggest lever for reducing the hazard.
- A study is only valid while the network and protection settings match the model.
What an Arc Flash Study Produces
For each switchboard, MCC and panel, the study reports the available incident energy (in cal/cm²) at a defined working distance, the arc flash boundary — the distance at which incident energy falls to 1.2 cal/cm² — and the information needed to select protective equipment and working procedures. Results are only as good as the network model behind them: accurate short circuit data and real protection settings matter more than any software default.
What Changed in IEEE 1584-2018
The 2018 edition replaced the earlier empirical model. It considers five electrode configurations, enclosure dimensions and conductor gap, and applies from 208 V to 15 kV. Vertical conductors in a box, for example, can produce markedly higher incident energy than the old method predicted. Plants studied under the 2002 method should expect some results to move when re-studied.
Where the Hazard Comes From
Incident energy rises with arcing current and, above all, with the time the arc lasts. That is why protection coordination and arc flash are studied together: a slow upstream device that clears a downstream fault can dominate the result.
Common Mitigation Options
Faster clearing through revised settings or maintenance-mode switches, zone-selective interlocking, bus differential protection, arc-resistant switchgear and remote racking or switching all reduce exposure. The right choice depends on where the energy comes from — which the study shows.
How We Approach It
We model the plant in ETAP, verify protection settings against site records, run the IEEE 1584 calculation and report results against the limit, with prioritised mitigation. Where the hazard is high, we can manage an arc flash mitigation programme and train your team.
Frequently Asked Questions
How often should an arc flash study be updated?
Whenever the network, fault level or protection settings change — and as a periodic review. A study no longer matches the plant once equipment or settings have changed.
Does a higher fault level always mean higher incident energy?
No. A higher fault current can make protection operate faster and reduce incident energy. The combination of arcing current and clearing time decides the result.
