IEEE 1584 is the engineering standard that defines how arc flash incident energy is calculated — the methodology that every arc flash study provider uses to produce the cal/cm² values that appear on arc flash warning labels and determine PPE requirements. For Ontario facilities whose arc flash studies were completed before approximately 2019, understanding the 2018 revision to this standard is important: a study based on the 2002 methodology may produce results that are materially different — at some equipment types, substantially different — from the current 2018 methodology.
This article explains what changed between IEEE 1584-2002 and IEEE 1584-2018, why the revision happened, and what it means for Ontario employers managing arc flash study currency.
Background: What IEEE 1584 Does
IEEE 1584 is the Guide for Performing Arc-Flash Hazard Calculations, published by the Institute of Electrical and Electronics Engineers. It provides the empirically derived calculation methodology for determining arc flash incident energy at electrical equipment. CSA Z462-24 requires that Ontario arc flash studies use the IEEE 1584-2018 methodology for incident energy analysis — specifically the approach described in Annex D of the standard.
The standard is not a theoretical derivation — it is an empirical model based on physical arc flash testing. Researchers intentionally create arc flash events under controlled conditions at various equipment configurations, voltages, and gap sizes, measure the incident energy at specified distances, and develop the mathematical model that best fits the experimental results. The model is only as accurate as the test data underlying it.
Why the 2002 Standard Was Revised
The 2002 edition of IEEE 1584 was based on a set of arc flash tests conducted under specific laboratory conditions. As the standard was applied in industry, researchers and practitioners identified limitations:
Limited equipment configurations tested. The 2002 test program covered specific electrode configurations and gap sizes. When applied to equipment configurations outside the original test range — open bus configurations, equipment with different gap geometries, systems with specific box configurations — the 2002 equations were extrapolated beyond the test data underlying them.
Systematic bias at certain configurations. Analysis of 2002-methodology results compared to subsequent testing revealed that the 2002 model systematically under- or over-predicted incident energy for certain equipment configurations. At some box-type equipment configurations, the 2002 model underestimated incident energy — meaning workers at those locations may have been under-protected compared to the actual hazard. At other configurations, it overestimated.
Inadequate coverage of medium-voltage equipment. The 2002 standard’s applicability to medium-voltage equipment (above 600V) was limited, and its results at medium-voltage switchgear were less reliable than at low-voltage equipment.
The 2018 revision addressed these limitations through a new, significantly expanded test program — over 2,000 arc flash tests at multiple laboratories, covering a much wider range of equipment types, configurations, gap sizes, voltages, and electrode orientations. The resulting model is substantially more sophisticated and more accurate across a wider range of real-world equipment configurations.
Key Technical Changes in IEEE 1584-2018
New Multi-Variable Equation Set
The 2002 standard used a relatively simple set of equations to calculate arcing current and incident energy. The 2018 standard replaces these with a multi-dimensional model that accounts for additional variables:
- Equipment configuration — whether the equipment is an open-air bus, box configuration (like a typical panel), or a specific configuration category defined in the standard (VCB, VCBB, HCB, VOA, HOA)
- Bus gap — the distance between conductors at the arc point, which significantly affects arc flash characteristics
- Electrode orientation — whether the arc occurs between vertically mounted or horizontally mounted conductors
- Enclosure dimensions — for box-type configurations, the width and height of the enclosure affect how the arc flash energy is reflected and concentrated
These additional variables allow the 2018 model to produce different (and more accurate) results at equipment configurations that the 2002 model treated with a single generalized formula.
Current-Interpolation Approach
The 2018 standard introduces a current-interpolation approach that calculates incident energy at both the arcing current predicted by the model and at a lower arcing current value, then uses the higher result. This addresses a known non-linearity in arc flash behavior where lower arcing currents can produce higher incident energy at some equipment types — a phenomenon the 2002 standard did not capture.
Improved Medium-Voltage Coverage
The 2018 standard substantially expands the applicability and accuracy of arc flash calculations at medium-voltage equipment (601V to 15,000V). This is important for Ontario industrial facilities with medium-voltage switchgear — mining operations, large manufacturers with dedicated substation equipment, and primary metals facilities — where 2002-methodology results at medium-voltage buses were particularly uncertain.
What This Means for Arc Flash Studies in Practice
Studies Based on IEEE 1584-2002 May Be Significantly Wrong at Some Locations
The direction of the error varies by equipment type. At some configurations, the 2018 methodology produces higher incident energy values than the 2002 methodology — meaning workers at those locations may be under-protected if they are wearing PPE selected based on a 2002-methodology study. At others, the 2018 methodology produces lower values than 2002 — meaning workers may have been wearing unnecessarily heavy PPE.
The magnitude of the difference can be significant. At certain box-type equipment configurations, incident energy values can differ by 30 to 50% between 2002 and 2018 methodology results. At those locations, the difference between the two methodologies could be the difference between a Category 2 and Category 3 PPE requirement.
Ontario Employers With Pre-2019 Studies Should Treat Them as Expired
CSA Z462-24 explicitly requires that arc flash studies use the IEEE 1584-2018 methodology. A study based on the 2002 methodology does not meet this requirement — regardless of when it was performed. Ontario employers with studies completed before approximately 2019 (when most providers had updated their software to implement the 2018 methodology) should:
- Confirm with their provider which edition of IEEE 1584 was used for the calculations
- If the study was based on IEEE 1584-2002, treat the study as expired and commission an update to the 2018 methodology
- Do not treat the five-year update cycle as the controlling deadline for 2002-methodology studies — the methodology update is an independent trigger
Medium-Voltage Equipment Deserves Particular Attention
For Windsor’s automotive operations and Hamilton’s primary metals facilities — which commonly have medium-voltage switchgear and substations — arc flash studies based on the 2002 standard at medium-voltage equipment locations are particularly likely to produce results that differ materially from 2018-methodology calculations. These are also the highest-energy and highest-consequence locations in those facilities. Prioritizing methodology update for medium-voltage equipment is appropriate.
How to Confirm Which Methodology Your Study Uses
The methodology used in your arc flash study should be identifiable from the report’s methodology section or from the software output tables. Look for:
- An explicit reference to “IEEE 1584-2018” or “IEEE 1584-2002” in the methodology description
- The software version used for the calculations — if the software is identified as ETAP 16 or later, SKM 8 or later, or EasyPower 10 or later, these versions implement the 2018 methodology; older versions may use 2002
- The presence of equipment configuration classifications (VCB, VCBB, HCB, VOA, HOA) in the output — these classification categories are specific to the 2018 methodology and will not appear in 2002-methodology output
If you cannot determine the methodology from the report, ask your arc flash study provider directly. A straightforward question — “Was our study performed using IEEE 1584-2002 or IEEE 1584-2018?” — should receive a clear answer. If the provider cannot confirm the edition, that is itself informative.
The Bottom Line
IEEE 1584-2018 represents a genuine improvement in the accuracy and applicability of arc flash calculation methodology — not a minor administrative update. Ontario employers who are using arc flash studies based on the 2002 standard are working from results that may not accurately reflect the arc flash hazard at their equipment, in a direction (overestimated or underestimated) that cannot be determined without running the 2018 calculations.
CSA Z462-24’s explicit requirement for the 2018 methodology removes any ambiguity about whether an update is needed: if your study was performed to IEEE 1584-2002, it does not comply with the current edition of CSA Z462, regardless of its age. Commissioning an update based on the 2018 standard is both a compliance obligation and a practical improvement in the accuracy of your workers’ PPE guidance.
Our arc flash study guide covers what a complete, current-methodology study involves. Use our free cost estimator to get a cost range for an update at your Ontario facility.