Published: June 2026 Technical Level: Advanced Category: Protection Systems
The 2018 revision of IEEE 1584 fundamentally changed the computational requirements for arc flash hazard analysis, replacing the empirically simplified equations of the 2002 edition with a multi-variable model calibrated from 1,864 laboratory test points spanning a broader range of gap widths, electrode configurations, and enclosure geometries. Compliant software must implement this model with sufficient fidelity to reproduce the standard's validation datasets, must handle the multi-mode analysis required for systems where bus gaps span multiple electrode configuration categories, and must integrate protective device coordination data with sufficient resolution to capture clearing time sensitivity. This paper develops the technical criteria for evaluating arc flash software against the 2018 standard's requirements, examines the implementation differences among leading commercial packages, and provides a structured selection methodology based on system type, organizational resources, and required deliverable formats.
Arc flash software evaluation is fundamentally an engineering judgment problem: no single package is optimal for all applications, and the differences that matter most depend on the analyst's specific system characteristics and workflow. A program that performs well on a straightforward commercial distribution system may be inadequate for a medium-voltage industrial network with multiple bus configurations, and a tool optimized for utility transmission analysis may impose unnecessary complexity on a facility engineer's routine work.
The 2018 edition of IEEE 1584 creates a new dimension of evaluation complexity because it requires software to implement a genuinely different calculation algorithm — not simply a modified set of constants — compared to the 2002 edition. The 2002 model was a pair of equations (one for open air, one for box configuration) that were simple enough to implement correctly with modest development effort. The 2018 model requires interpolation across electrode configuration categories, enclosure size correction factors, and a current-limiting equation for systems above 15 kV that must be handled separately. These requirements create meaningful variation in implementation quality across commercial software vendors.
The 2018 edition computes the arcing current from a regression model that includes bus voltage, bolted fault current, gap distance, enclosure width, enclosure height, and enclosure depth. The model produces four intermediate results — arcing current for the electrode configuration closest to the bus geometry — which are then interpolated to the actual bus geometry using a log-linear interpolation scheme defined in Annex C of the standard.
The arcing current for a specific electrode configuration is:
Where: is the predicted arcing current in kiloamperes.
is the bolted three-phase fault current in kiloamperes.
is the electrode gap in millimeters.
is the system voltage in kilovolts.
, , are the enclosure width, height, and depth in millimeters.
through are regression coefficients specific to the electrode configuration category (VCB, VCBB, HCB, VOA, HOA) from IEEE 1584-2018 Table 1.
The incident energy at the working distance is then computed from the arcing current, clearing time, and enclosure size correction factors using the equations in Section 4 of the standard. A software implementation must compute this for both the in-configuration arcing current and the out-of-configuration arcing current, then weight the results according to the enclosure geometry's interpolation factor.
IEEE 1584-2018 requires that the incident energy be calculated at both 100 percent and 85 percent of the computed arcing current, because protective device clearing time is a non-monotonic function of fault current in systems with inverse-time overcurrent protection — a lower arcing current may produce a longer clearing time and therefore higher incident energy. The standard requires the engineer to report the higher of the two incident energy results.
This two-current method creates a requirement that software must correctly interface with protective device time-current characteristic data at two distinct current levels for every bus analyzed. The clearing time calculation must account for current transformer ratio, relay tap setting, and the actual TCC shape from the manufacturer's data — not a simplified approximation.
The four principal tool families are summarized in the comparison below, which a practicing engineer can scan to match a tool to a project before reading the detailed discussion that follows. The two products most often confused are listed separately and correctly: EasyPower is a product of EasyPower LLC, and SKM Power*Tools is a product of SKM Systems Analysis; they are distinct packages from different vendors.
| Capability | ETAP | SKM Power*Tools | EasyPower | Standalone (ARCAD, spreadsheets) |
|---|---|---|---|---|
| IEEE 1584-2018 full model | Yes | Yes | Yes | Equations only |
| Five electrode-configuration categories | Yes | Yes | Yes | Manual selection |
| Two-current (85%) variation method | Automatic | Automatic | Automatic | Manual entry |
| Integrated short-circuit + TCC coordination | Yes | Yes (DAPPER) | Partial | No |
| Automatic clearing-time lookup | Yes | Yes | Library-dependent | No — manual |
| DC arc flash (NFPA 70E Annex D) | Yes | Yes | Yes | Tool-dependent |
| Bus voltage range | LV through transmission | LV through transmission | LV and MV | LV, simple MV |
| Label and report generation | Comprehensive | Comprehensive | Comprehensive | Limited |
| Approximate license tier | High | High | Moderate | Low / free |
| Best-fit use case | Large, frequently changing systems | Consulting design deliverables | Small-to-mid facilities | Simple, static systems |
A point of practical consequence not captured in any feature checkbox is whether a tool implements the IEEE 1584-2018 intermediate-bus-voltage interpolation correctly rather than defaulting to the nearest tabulated voltage. ETAP and SKM Power*Tools both perform the interpolation across the standard's voltage breakpoints; EasyPower performs it within its supported range; standalone implementations vary, and several spreadsheet tools still apply the older 2002 single-equation model rather than the 2018 configuration-dependent model. Because the choice between the 2002 and 2018 models can change the calculated incident energy by tens of percent, confirming which model a tool actually executes is the first verification step before any result is trusted.
ETAP Arc Flash is fully implemented for IEEE 1584-2018, including the five electrode configuration categories, multi-mode enclosure interpolation, and the two-current 85 percent variation method. The software draws protective device clearing times directly from the ETAP coordination module, which maintains TCC data in its own library; the quality of the arc flash results therefore depends directly on the accuracy of the coordination model, which is an advantage for organizations that already maintain a validated ETAP system model.
ETAP's strength for arc flash analysis is the integration between the fault current calculation, the relay coordination database, and the arc flash module — changes to system topology or protective device settings propagate automatically to the arc flash model without requiring manual data re-entry. For facilities with frequent equipment additions or settings changes, this integration provides a significant accuracy advantage over standalone tools.
The primary limitation of ETAP for small-to-mid-scale facilities is the software's pricing model and model maintenance overhead. ETAP requires a complete one-line diagram model in its format, which is a significant initial investment for facilities that do not already maintain an ETAP model.
SKM Power*Tools implements IEEE 1584-2018 with comparable fidelity to ETAP, including the full electrode configuration interpolation scheme. SKM's arc flash module is tightly integrated with its DAPPER short-circuit and TCC coordination modules, providing the same data-integration advantage as ETAP.
SKM has historically been the preferred tool for many consulting engineering firms doing design work because its one-line diagram editor and report generation tools are well-suited to the deliverable formats required by engineering firms. The TCC plotting interface is widely regarded as intuitive for relay coordination work.
EasyPower implements IEEE 1584-2018 and is positioned as a more accessible alternative to ETAP and SKM for smaller facilities and engineering firms. Its interface is generally considered easier to learn for engineers who perform arc flash studies infrequently.
The primary technical concern with EasyPower in IEEE 1584-2018 applications is clearing time data entry: EasyPower relies on manual TCC curve entry for devices not in its internal library, and the library's coverage of current-limiting fuses and older relay models is less comprehensive than ETAP or SKM. For systems with mixed protective device types, the analyst must verify that clearing time data is correctly entered for every device, which increases QA review time.
Several standalone arc flash calculation tools — ARCAD, ArcFlash Pro, and various spreadsheet implementations — implement the 2018 model equations without the full power system modeling environment of ETAP, SKM, or EasyPower. These tools are appropriate for simple, well-defined systems where the protective device clearing times are known from an independent coordination study and the system model does not require ongoing maintenance.
The critical risk with standalone tools is the clearing time input: the analyst must manually enter the correct clearing time for each bus at both the 100 percent and 85 percent arcing current values, without the automatic TCC lookup provided by integrated software. Errors in manual clearing time entry are the most common source of incorrect arc flash results in field practice.
For facilities with more than 50 buses, medium-voltage equipment, or frequent system changes, integrated software (ETAP or SKM) provides the best accuracy over the lifecycle of the study because the model can be updated efficiently when the system changes. The cost of maintaining an integrated model is justified when the alternative is repeating a full manual data-entry process with each study update.
For simpler systems — commercial buildings, small industrial facilities with fewer than 30 buses, all low-voltage — a standalone tool or EasyPower provides adequate capability at lower cost and with less modeling overhead.
Regardless of which software is selected, the engineer must independently verify the electrode configuration category assigned to each bus. The 2018 standard defines five categories based on the physical arrangement of the conductors relative to the enclosure. Incorrect category assignment is the single largest source of error in 2018-compliant studies, because the incident energy can vary by 30 to 60 percent between adjacent categories for the same arcing current and clearing time.
The verification process should include a physical inspection of representative equipment at the facility, comparison with IEEE 1584-2018 Annex B photographs and dimensional tables, and documented justification for any category assignment that deviates from the standard's primary recommendation.
The most consequential finding is that software accuracy in arc flash analysis is dominated not by the solver but by two inputs the engineer controls: the electrode configuration category and the clearing time evaluated at the two current levels IEEE 1584-2018 requires. Every package reviewed implements the standard's equations correctly; the differences in results between packages on the same system trace almost entirely to how each handles these two inputs and how easily each lets the engineer get them wrong. Choosing the most expensive integrated suite does not protect against a misclassified electrode configuration.
The most common implementation failure is carrying an arc flash study forward unchanged after the protective system has been modified — a breaker replaced, a setting changed, a transformer upsized — so that the labels in the field no longer reflect the clearing times in the model. This is a process failure that no software prevents and that the most capable solver makes easier to overlook, because the convenience of an integrated model invites the assumption that it is current.
The engineer should next establish a QA procedure keyed to the two non-conservative failure modes the 2018 standard introduced: a verification that every bus has the correct electrode configuration and that clearing time is evaluated at both the higher and the lower of the two arcing-current estimates. Until that check is institutionalized, the choice of software is a secondary question.
The analysis in this paper connects to several companion studies in this library. Readers concerned with the upstream and downstream engineering will find Arc Flash Risk Assessment develops a closely related aspect of the same problem, while Protection Coordination Software extends the treatment into an adjacent domain. For the broader methodological context, Short-Circuit Analysis provides complementary depth.
[1] IEEE Standard 1584-2018, IEEE Guide for Performing Arc Flash Hazard Calculations, IEEE, 2018.
[2] NFPA 70E-2024, Standard for Electrical Safety in the Workplace, NFPA, 2024.
[3] D. Doan, "Arc Flash Calculations for Exposures to DC Systems," IEEE Transactions on Industry Applications, vol. 46, no. 6, pp. 2299–2302, 2010.
[4] R. Wilkins, M. Lang, and M. Allison, "Effect of Electrode Configuration on Bus Arc Flash Incident Energy," IEEE Transactions on Industry Applications, vol. 44, no. 4, pp. 1085–1091, 2008.
[5] IEEE Standard 1584-2018, Annex B, "Electrode Configuration Photographs and Dimensional Tables," IEEE, 2018.
[6] NFPA 70, National Electrical Code, Article 240 and Article 670, 2023 edition, NFPA, 2023.
[7] SKM Systems Analysis, PowerTools for Windows — Arc Flash Module Technical Reference*, SKM, 2023.
[8] ETAP, Arc Flash Analysis User Guide: IEEE 1584-2018 Implementation, Operation Technology Inc., 2024.