About the Arc Flash Boundary Estimator Online Free Tool

The Arc Flash Boundary Estimator Online Free Tool provides a simplified screening estimate for incident energy at working distance and an approximate arc-flash boundary.

It uses the Lee method (R. H. Lee, IEEE Transactions on Industry Applications, 1982, referenced in NFPA 70E Annex D), which models the theoretical maximum energy of an open-air arc as E = 2.142 × 10⁶ × V × I_bf × t / D², with voltage in kV, bolted fault current in kA, time in seconds, distance in mm, and energy in J/cm².

How to Use the Arc Flash Boundary Estimator Online

1. Enter system voltage, bolted fault current, arc duration, and working distance.
2. Keep the boundary threshold at 1.2 cal/cm² unless your site uses a different onset-of-second-degree-burn value.
3. Run the estimator to review incident energy and boundary distance.

Choosing Options Correctly

This is a simplified educational estimate, not a full IEEE 1584 or NFPA 70E study. Real studies require equipment class, gap, enclosure, fault clearing data, protective device settings, and qualified review.

Bolted fault current:
- Enter the available bolted (prospective) fault current, not the reduced arcing current.
- Lee's method is defined in terms of bolted fault current and is intentionally conservative.

Where this method applies:
- Lee's method models an open-air arc and is the referenced approach above 15 kV or outside the IEEE 1584 empirical range.
- For arc-in-a-box equipment at low voltage it typically overestimates energy, so treat the result as an upper bound and use an IEEE 1584 study for real PPE decisions.

Common Use Cases

• Explore how arc duration affects boundary distance.
• Screen early electrical safety assumptions.
• Explain arc-flash sensitivity during training.

Quick FAQ

Can this assign PPE categories?
No. It is not a substitute for an arc-flash study, label, or PPE category assignment under the governing standard.

Does this save any hazard data?
The page calculation does not need server-side storage; avoid entering sensitive facility details unless required for your own records.

Which standards should I verify against?
Use the current requirements that apply to your site, such as NFPA 70E and IEEE 1584 where applicable.

What inputs are critical?
Available fault current, clearing time, working distance, enclosure type, electrode configuration, and system voltage strongly affect incident energy.