IEEE 1584-2018 Explained: What Changed in Your Label Data

Last Updated: 2026-10-22

Answer Capsule: IEEE 1584-2018 is the calculation standard behind the incident energy on an arc flash label. It replaced the 2002 model, adding electrode configuration, an enclosure size correction and a 2 second maximum clearing time convention. It also removed the exemption for systems under 240 V fed by transformers under 125 kVA. Studies still based on 1584-2002 should be re-run.

Your facility has arc flash labels on every panel, and every one of them came from a study done in 2014. Then a new safety manager asks a simple question: "Which edition of IEEE 1584 did the engineer use?"

If the answer is 2002, the numbers on your labels may be wrong. IEEE 1584-2018 replaced the calculation model, and the new model can move incident energy values up or down on the same piece of gear.

This guide from Print Pro AZ explains what IEEE 1584 is, what changed between the 2002 and 2018 editions, why older studies need a re-run, and what changes on the label when the new numbers come back. Brent Hanke, founder of Print Pro AZ, sees study tables from both editions land on his desk. Here is how to tell them apart and what to do next.

What Is IEEE 1584 and Why Does It Matter for Arc Flash Labels?

IEEE 1584 is the IEEE Guide for Performing Arc-Flash Hazard Calculations, and it is the calculation standard behind the incident energy value on your arc flash label. NFPA 70E tells you that you need an arc flash risk assessment. IEEE 1584 tells the engineer how to compute the numbers that assessment produces.

Where it fits. NFPA 70E-2024 Section 130.5 requires the arc flash risk assessment. Section 130.5(G) lets you choose the incident energy analysis method or the PPE category method. When you choose incident energy, the engineer needs a way to calculate it. IEEE 1584-2018 is that method.

What it produces. The 1584 calculation returns two numbers for each piece of equipment: the incident energy at the working distance, in cal/cm2, and the arc flash boundary, the distance at which incident energy drops to 1.2 cal/cm2. Both numbers go on the label under NFPA 70E-2024 Section 130.5(H).

What Changed From IEEE 1584-2002 to 1584-2018?

IEEE 1584-2018 replaced the 2002 calculation model and added four changes that affect nearly every label. Here they are side by side.

Item	IEEE 1584-2002	IEEE 1584-2018
Calculation model	Original 2002 empirical model	New model that replaced the 2002 equations
Electrode configuration	Not a modeled input	Five configurations: VCB, VCBB, HCB, VOA, HOA
Enclosure size	Not corrected for	Enclosure size correction factor added
Maximum clearing time	No fixed convention	2 second maximum clearing time convention
Systems under 240 V from a transformer under 125 kVA	Could be treated as exempt	Exception removed; these systems must be calculated

Enclosure size correction adjusts the result for the interior dimensions of the box, so the 2018 method asks for measurements.

The 2 second convention caps the clearing time used in the calculation at two seconds in most cases.

The 240 V exception catches the most facilities off guard. Under 2002, many 208 V panels were skipped. Under 2018, that shortcut is gone.

What Is Electrode Configuration and Why Does It Change the Number?

Electrode configuration is the orientation of the conductors where the arc forms, and it changes the number because it changes where the arc plasma goes. Vertical conductors tend to push the arc downward and away from the worker. Horizontal conductors point it straight out of the enclosure, toward the person standing in front of it.

Here are the five configurations in IEEE 1584-2018:

• VCB: vertical conductors inside a metal box
• VCBB: vertical conductors inside a box, ending in an insulating barrier
• HCB: horizontal conductors inside a metal box
• VOA: vertical conductors in open air
• HOA: horizontal conductors in open air

Under the 2018 model, HCB can produce a higher incident energy than VCB for the same fault current and clearing time. That means two panels with identical breakers and identical fault current can have different numbers on their labels, based only on how the bus is oriented.

What this means in the field. Someone has to open the equipment and look. A study that lists every panel as VCB without a site visit deserves a second look.

Print Pro AZ tip: when your study table arrives, check for an electrode configuration column. If it is missing, ask the engineer. A 2018 study without configuration data is not complete, and Brent Hanke flags this on incoming files.

Why Do Studies Based on IEEE 1584-2002 Need a Re-Run?

Any study still based on IEEE 1584-2002 should be re-run because the 2018 edition replaced the calculation model, not just adjusted it. A label built on the old numbers reports a hazard the current standard would calculate differently.

Three rules make this more than a suggestion:

1. NFPA 70E-2024 130.5(H) requires the method of calculation and the supporting data to be documented, reviewed at intervals not to exceed 5 years, and updated when a change in the electrical distribution system could affect the results. A study done before 2019 has almost certainly passed the 5-year mark.
2. The removed 240 V exception means equipment that was skipped under 2002 now needs a calculation. If your old study has blank rows for small 208 V panels, those panels are unlabeled under the current method.
3. NEC 2026 Section 110.16 requires the label to show the date the assessment was completed. An assessment date from 2014 on a label installed in 2026 invites the inspector to ask which edition was used.

The results can change in either direction. Some equipment comes back higher because of electrode configuration, some lower because of the 2 second convention. Neither outcome is safe to assume without running the calculation.

Here is a call Print Pro AZ gets every month. A facility manager sends a 2015 study PDF and asks for a full set of replacement labels because the old ones faded. Print Pro AZ can print exactly what is in the file, but it is based on 1584-2002 and the assessment date will read 2015.

The better move is a re-run first, then a label set from the new table. Print Pro AZ tells the customer that before printing anything.

What Changes on the Label After a 1584-2018 Study?

After a 1584-2018 study, the incident energy value, the arc flash boundary and the assessment date on the label all change, and some equipment may move to a different PPE requirement.

• Incident energy at working distance. The number may go up or down. The working distance itself usually stays the same, commonly 18 inches for 600 V class equipment.
• Arc flash boundary. This is the distance where incident energy falls to 1.2 cal/cm2. It moves with the incident energy value.
• Assessment date. The label must show the date the new assessment was completed, not the date the label was applied.
• Nominal system voltage. Usually unchanged, unless the system itself changed.
• Shock boundaries. The limited and restricted approach boundaries come from NFPA 70E Table 130.4(E)(a), not from IEEE 1584, so they stay put unless the voltage changed.
• Newly labeled equipment. Panels that were skipped under the old 240 V exception now get a label for the first time.

One rule does not change. NFPA 70E-2024 130.5(G) still lets you show incident energy or a PPE category, never both on the same label. A re-run does not change that. For every field the label must carry, see the Print Pro AZ guide to arc flash labels under NFPA 70E 2024.

How Do You Know Which Edition Your Study Used?

You can tell which edition your study used by checking the method section of the report, the study date, and whether the incident energy table has an electrode configuration column. Here is the quick check Print Pro AZ runs on every incoming file.

1. Read the methodology page. A compliant report names the calculation standard and edition. Look for "IEEE 1584-2018" in writing.
2. Check the study date. A report dated before 2019 was almost certainly done under 2002. A report dated after 2019 should say 2018, but confirm it.
3. Look for electrode configuration. A 2018 table lists VCB, VCBB, HCB, VOA or HOA for each piece of equipment. A 2002 table does not have this column.
4. Look for small panels. If 208 V panels fed by small transformers show "not calculated" or are missing, the study used the old exception.
5. Ask the engineer. A licensed engineer can confirm the edition in one email.

Once you have a 2018 table, the label order is simple. Print Pro AZ takes the study data as a PDF, Excel or CSV file and prints the set on UV-rated polyester or .048 aluminum, shipped the same week. To understand every input the engineer used, read the Print Pro AZ guide to how incident energy in cal/cm2 is calculated.

Frequently Asked Questions

Is IEEE 1584-2018 the current edition?

IEEE 1584-2018 is the edition used for arc flash incident energy studies. It replaced IEEE 1584-2002. Check the IEEE standards page for any amendments before your next study.

Does NFPA 70E require IEEE 1584?

NFPA 70E-2024 does not name a required calculation method. It requires an arc flash risk assessment under 130.5 and, under 130.5(H), documentation of the method and data behind the label. IEEE 1584-2018 is the standard engineers use to meet that requirement when the incident energy method is chosen.

How often does an IEEE 1584 study need to be updated?

NFPA 70E-2024 130.5(H) requires the label data to be reviewed at intervals not to exceed 5 years and updated when a change in the electrical distribution system could affect the results. A study based on IEEE 1584-2002 should be re-run regardless of age, because the calculation model changed.

What are VCB, VCBB, HCB, VOA and HOA?

They are the five electrode configurations in IEEE 1584-2018. VCB is vertical conductors in a box, VCBB is vertical conductors in a box ending in a barrier, HCB is horizontal conductors in a box, and VOA and HOA are the vertical and horizontal open-air versions.

Can a small 208 V panel still be exempt from an arc flash study?

No. IEEE 1584-2002 allowed systems below 240 V fed by a single transformer under 125 kVA to be treated as low risk without a calculation. IEEE 1584-2018 removed that exception. Those panels now need a calculated incident energy and a label like any other equipment.

Conclusion

IEEE 1584-2018 replaced the 2002 calculation model and added electrode configuration, enclosure size correction, a 2 second clearing time convention and a calculation requirement for small 208 V systems. Any study still based on 1584-2002 should be re-run. After the re-run, the incident energy, arc flash boundary and assessment date on every label change.

Getting the study edition right before you print saves you a second label order and an inspection re-trip. Print Pro AZ prints arc flash labels on UV-rated polyester and .048 aluminum from your updated study table.

Have a new study table? Send us your plan sets and Print Pro AZ will build the label set. Questions? Call Brent: (602) 649-5305.

Sources

• IEEE 1584-2018, IEEE Guide for Performing Arc-Flash Hazard Calculations
• NFPA 70E, Standard for Electrical Safety in the Workplace

Brent Hanke | Print Pro AZ | (602) 649-5305 | b.hanke@printproaz.com

Brent Hanke is the founder of Print Pro AZ, supplying NEC-compliant labels to contractors across the country.