Code Reference
ElectricalIEEE 1584-2018

Section 4/Arc Flash Hazard Calculation Model

IEEE 1584 Section 4 presents the empirical model for calculating incident energy and arc flash boundary from system parameters.

What this section requires

The IEEE 1584 model calculates the incident energy (in cal/cm2) at a specified working distance from an arc flash event. The inputs are: system voltage (208V to 15kV), bolted fault current (available at the equipment), gap between conductors, enclosure type and size, grounding configuration, and the arc duration (protective device clearing time). The 2018 edition significantly revised the model from the 2002 edition, extending the voltage range and improving accuracy for a wider range of equipment configurations.

Why this section exists

Arc flash incident energy determines the severity of burn injuries and drives the PPE requirements for workers. The IEEE 1584 model is the industry standard for quantifying this hazard. Without a validated calculation method, there would be no way to rationally select PPE or assess the effectiveness of arc energy reduction measures. The model is based on extensive laboratory testing of arc flash events under controlled conditions.

What plan reviewers look for

Plan reviewers who evaluate arc flash studies check the input data against the electrical one-line diagram: voltage, available fault current (per NEC 110.24), protective device type and settings, working distance, and enclosure configuration. They verify that the 2018 edition model is used (not the superseded 2002 model) and that the results are reflected in arc flash labels per NEC 110.16.

Common violations

Study uses superseded 2002 model
The arc flash study references the 2002 edition of IEEE 1584, which has been shown to underestimate incident energy for some configurations. The 2018 edition model should be used for new studies.
Available fault current does not match one-line
The fault current used in the arc flash calculation differs from the value shown on the electrical one-line diagram. Both must be consistent and based on the same system configuration.
Clearing time not verified with protection settings
The arc flash study assumes a specific protective device clearing time that does not match the actual device settings. The clearing time is the single most influential variable in the incident energy calculation.
Compliance tip
Ensure the arc flash study uses the IEEE 1584-2018 model. Verify all inputs against the electrical one-line diagram. Confirm protective device settings with the protection coordination study. Show incident energy results on the one-line diagram or in a separate arc flash schedule.

Related IEEE 1584 requirements

Section 8 covers the arc flash boundary calculation. NEC 110.16 requires arc flash labels. NFPA 70E Section 130.5 requires the arc flash risk assessment. NEC 240.87 covers arc energy reduction methods that can lower incident energy levels.

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Related sections

110.16Arc Flash Hazard WarningNEC 2023130.5Arc Flash Risk AssessmentNFPA 70E8Arc Flash BoundaryIEEE 1584-2018