IEEE 1584 is the Guide for Performing Arc Flash Hazard Calculations. It provides the engineering method for calculating how much energy would be released at a piece of electrical equipment if an arcing fault occurred, and how far away a worker needs to be to stay safe. Most arc flash studies use IEEE 1584 as the calculation method, and most power system analysis software implements it directly.
Arc flash analysis and arc flash risk assessments are the process and the requirement. IEEE 1584 is the calculation engine behind the incident energy numbers that drive PPE selection, arc flash boundary distances, and equipment labels.
What IEEE 1584 is
IEEE 1584 is an empirical standard, meaning its equations are derived from physical test data rather than theoretical first principles. The Institute of Electrical and Electronics Engineers developed the model by conducting controlled arc flash tests across a range of voltages, fault current levels, equipment types, and configurations, then fitting mathematical equations to the observed results.
The current edition, IEEE 1584-2018, was developed from more than 1,800 arc flash tests. That test program took over a decade. The result is a model that accounts for variables the original 2002 edition ignored, and that produces more accurate incident energy predictions across a wider range of system types.
The 2018 edition vs. the 2002 edition
IEEE 1584 was first published in 2002. The 2002 model used a simpler set of equations and did not account for equipment configuration, electrode gap, or grounding type as distinct input parameters. For many systems, it produced conservative results. For some, it produced results that did not accurately reflect actual arc flash behavior.
The 2018 edition introduced significant changes:
- Five distinct equipment configurations, each with separate equations and coefficients
- Electrode gap is an explicit input that affects arcing current and incident energy
- Grounding type affects arcing current calculation (solidly grounded systems behave differently from ungrounded or high-resistance grounded systems)
- Enclosure dimensions affect incident energy calculations for enclosed equipment configurations
- The voltage range 208V to 15kV is more rigorously validated than in the 2002 model
Facilities that had arc flash studies performed under the 2002 model should understand that the 2018 model may produce different results for the same equipment. Some equipment will show higher incident energy under 2018; some will show lower. The direction depends on the specific configuration and parameters. When the five-year review comes around, the engineer will determine whether results need to be recalculated under the 2018 model.
What IEEE 1584 covers
IEEE 1584-2018 applies to three-phase AC electrical systems with voltages from 208V to 15kV. It covers systems where workers may be exposed to arc flash hazards during maintenance, inspection, or operation of electrical equipment.
Systems outside the 208V to 15kV range are not directly covered. Single-phase systems are not covered. DC systems are not covered. For these situations, engineers must use engineering judgment, extrapolation, or alternative calculation methods. NFPA 70E requires the hazard to be assessed regardless of voltage level, but the IEEE 1584 model may not directly apply to every situation.
Relationship to NFPA 70E
NFPA 70E requires an arc flash risk assessment. It specifies two acceptable methods for PPE selection: the incident energy analysis method and the PPE category method. IEEE 1584 is the industry-standard method for performing the incident energy analysis that satisfies NFPA 70E 130.5(F)(1).
NFPA 70E defines what must happen. IEEE 1584 defines how the engineering calculation is performed. You need both. NFPA 70E without IEEE 1584 tells you PPE is required but not what arc rating. IEEE 1584 without NFPA 70E is a calculation with no compliance framework around it.
The two standards are developed by separate organizations and on separate timelines. NFPA updates 70E on a three-year cycle. IEEE 1584 has been revised once since the original 2002 publication. They reference each other but are independently maintained.
Required input data
IEEE 1584 analysis requires a specific set of system parameters for each equipment location. The accuracy of the output depends entirely on the accuracy of these inputs. Errors in field data at this stage produce wrong incident energy values that end up on equipment labels.
| Input parameter | Description | Typical source |
|---|---|---|
| Available bolted fault current (kA) | Maximum prospective three-phase fault current at the equipment bus | Short circuit study; utility available fault current data |
| System voltage (kV) | Nominal operating voltage at the point being analyzed | Equipment nameplate; one-line diagram |
| Equipment configuration | Open air, VCB, VCBB, HCB, or cable; determines which IEEE 1584 equations apply | Field observation of equipment construction |
| Electrode gap (mm) | Distance between conductors at the potential arc location | IEEE 1584 Table 1 defaults by voltage class; field measurement if known |
| Enclosure dimensions (mm) | Width, height, depth of enclosure for enclosed configurations | Equipment nameplate; field measurement |
| Protective device type and settings | Breaker, fuse, or relay; trip curves and setting values | Field data collection; device documentation |
| Clearing time (seconds) | Time from fault initiation to arc current interruption | Coordination study; device time-current curves |
| Working distance (mm) | Distance from the worker's face to the potential arc source | NFPA 70E Table 130.5(C); field-specific measurement |
| Grounding type | Solidly grounded, ungrounded, or high-resistance grounded | System documentation; one-line diagram |
Download the free arc flash field data collection checklist covering every data point by equipment type, formatted for field use.
The five equipment configurations
Configuration is one of the most consequential inputs in the IEEE 1584 2018 model. The same fault current at the same voltage produces significantly different incident energy values depending on the physical arrangement of conductors and whether they are enclosed.
Open air (OA)
Arc energy radiates in all directions without reflective surfaces. Open air typically produces lower incident energy than enclosed configurations at equivalent system parameters. Substations, exposed bus work, and aerial configurations fall here.
Vertical conductors or buses in a box (VCB)
The enclosure walls reflect and focus arc energy toward the opening. This is a common configuration in metal-clad switchgear with vertical bus bars. Incident energy is typically higher than open air for the same parameters because the enclosure concentrates the energy.
Vertical conductors or buses in a box with insulating barrier (VCBB)
Similar to VCB but with an insulating barrier between the conductors and the worker. The barrier changes arc trajectory and typically reduces incident energy compared to VCB. Some modern switchgear designs incorporate barriers as an engineering control.
Horizontal conductors or buses in a box (HCB)
Common in panelboards and some motor control center designs where the bus runs horizontally. Arc propagation in horizontal bus configurations differs from vertical configurations, and the IEEE 1584 2018 model has separate equations for each.
Cable (CC)
Applies to cable terminations and cable tray systems. Arc behavior in cable configurations is distinct from rigid bus equipment. This configuration is less commonly the binding constraint in most facility arc flash studies but matters in cable-intensive installations.
Selecting the wrong configuration in the analysis software produces wrong results. This is a judgment call that requires the engineer to understand both the software model and the actual construction of the equipment being analyzed. Field engineers who have seen the inside of the equipment are better positioned to make this determination correctly than engineers working only from documentation.
What IEEE 1584 analysis produces
For each equipment location, the analysis produces:
- Arcing current (kA): The current that flows through the arc, lower than bolted fault current because arc impedance limits flow. IEEE 1584 2018 calculates both maximum and minimum arcing current values to account for the range of protective device response. Both values are evaluated to find the worst-case incident energy.
- Incident energy (cal/cm²): The thermal energy a worker at the specified working distance would receive during an arc flash event of the calculated duration. This is the primary output that drives PPE selection.
- Arc flash boundary (inches or mm): The distance from the potential arc source at which incident energy equals 1.2 cal/cm² per NFPA 70E 130.5(E)(1). Workers inside this distance require arc-rated PPE.
- Required PPE arc rating (cal/cm²): Minimum ATPV or Ebt for PPE worn at the working distance. Derived directly from the incident energy result.
These outputs go onto equipment labels and into the arc flash study report. They drive the PPE requirements that workers follow every time they open a panel or operate equipment near energized parts.
Why data accuracy determines result quality
IEEE 1584 is a deterministic model. Put in the right numbers, get the right answer. Put in wrong numbers, get a wrong answer that looks right on paper.
The available bolted fault current depends on accurate transformer impedance data. If a transformer nameplate shows 5.75% impedance but tested impedance is actually 4.9%, the fault current calculation at the secondary bus is wrong. Incident energy at every piece of equipment fed from that transformer is wrong.
Clearing time depends on accurate protective device settings. A main breaker that was supposed to have an instantaneous trip at 10x rating but was left at 6x from a previous project changes the clearing time calculation. Incident energy at the downstream bus shifts as a result.
These errors accumulate through the model. A study built on shaky field data produces labels that look professional but do not reflect actual hazard levels. Workers rely on those labels when deciding what PPE to put on.
70Ez was built to reduce data collection errors in exactly this phase. Field technicians photograph equipment nameplates. The AI reads nameplate data and populates the project record. The technician verifies. The data exports directly to SKM PowerTools, ETAP, or EasyPower, organized by equipment type and ready for model building. Manual transcription is removed from the process. See how arc flash data collection works with modern tools, and start a free trial.
The role of the short circuit and coordination studies
IEEE 1584 arc flash calculations require inputs from two upstream studies. These must be completed first.
The short circuit study calculates available bolted fault current at each bus in the electrical system. That current value is a primary input to the IEEE 1584 model. Run arc flash without a valid short circuit study and the fault current values are either assumed or wrong.
The protective device coordination study establishes clearing times by analyzing how devices respond to fault conditions. Clearing time is the other primary driver of incident energy. Faster clearing times mean lower incident energy. The coordination study finds the clearing time for the protective device upstream of each equipment location. The arc flash analysis then uses those clearing times to calculate how long the arc burns before it is interrupted.
Most engineering firms perform all three studies together as a single project. The short circuit and coordination results feed directly into the arc flash calculations in the same software model. See the arc flash study overview for how the full process is structured.
Frequently asked questions
Does IEEE 1584 apply to DC systems?
No. IEEE 1584 applies to three-phase AC systems in the 208V to 15kV range. DC arc flash is a separate phenomenon with different calculation methods. NFPA 70E does address DC systems, but IEEE 1584 is not the applicable calculation method for DC arc flash hazard assessment.
How does IEEE 1584 handle systems above 15kV?
IEEE 1584-2018 is validated up to 15kV. Systems above 15kV, such as medium-voltage transmission and distribution equipment above that threshold, fall outside the validated range. Engineers working on higher-voltage systems typically use engineering judgment, extrapolation, or other methods. The incident energy levels in high-voltage systems can be extreme, and the appropriate calculation approach should be discussed with the project engineer.
Will studies done under the 2002 model need to be redone?
Not necessarily immediately. NFPA 70E's five-year review requirement is the mechanism for transitioning to updated calculations. When the review comes due, the engineer evaluates whether the existing study is still valid. For studies still based on the 2002 model, that review is a good opportunity to update to the 2018 model, which may produce more accurate results for specific equipment types. Some equipment will show higher incident energy under 2018; some will show lower.
What software implements IEEE 1584?
The major power system analysis platforms all implement IEEE 1584-2018: SKM PowerTools, ETAP, and EasyPower. Each platform performs short circuit analysis, protective device coordination, and arc flash calculations in the same model. The engineer builds the system model, validates it against known values, and runs the arc flash module to produce incident energy results. See our arc flash study software guide for a comparison of the platforms.
How do motor contributions affect IEEE 1584 results?
Motors connected to a bus contribute fault current during an arcing fault, which increases the available fault current above what the utility alone would provide. IEEE 1584 analysis accounts for motor contributions through the short circuit study. Motors above a certain size threshold are modeled as current sources that add to available fault current at their connection points. Omitting motor contributions can understate fault current and therefore understate incident energy at equipment near large motor loads.