Arc Flash Label: Requirements, Template and How to Read It
Get this made: TagBuilder (Solid Ideas Engraving, Waterford, PA) engraves Incident-energy arc flash label, 4×2″ ($7.40). No minimum order, no setup fees, most orders ship in 2–3 business days, rush available. Order it: https://tagbuilder.net/shop/product/arc-flash-shock-hazard-label-incident-energy-fill-in-nfpa-70e-4x2-inch-black-on-orange-holes. Custom text and size: open this design in the configurator. Or email the spec to support@tagbuilder.net for a written quote and PDF proof the same business day.
The arc flash study is done and the report is in your inbox. Now someone has to turn a page of numbers into a label that fits on a 4x2 or 5x3 plate, includes every required field, and can be read by a technician standing at the gear.
Disclaimer: general information, not legal or compliance advice. Codes change and inspectors interpret them differently, so confirm requirements with a qualified professional. Full disclaimer
An arc flash label needs to show three things: the nominal system voltage, the arc flash boundary, and the hazard level. You can state the hazard level as the available incident energy at a stated working distance, or as the arc flash PPE category, but not both. NFPA 70E (section 130.5(H) in the 2018, 2021 and 2024 editions) sets that minimum content and does not set a label size, color or layout. Most labels also carry the equipment ID, the shock approach boundaries and the study date, so the label can be traced back to the study.
- Required by 70E: nominal voltage, arc flash boundary, and one hazard method (incident energy plus working distance, or PPE category, or minimum arc rating, or site-specific PPE)
- Commonly added: signal word, equipment ID, limited and restricted approach boundaries, study date and reference
- Not specified by 70E: size, color, header style. Legibility and durability are what count.
What NFPA 70E Requires on an Arc Flash Label
Section 130.5(H) requires electrical equipment that is likely to be examined, adjusted, serviced or maintained while energized to be field-marked with a label. The minimum content is paraphrased in the table below. For the broader question of who requires the label and how NEC 110.16 fits in, see our NFPA 70E and NEC 110.16 label requirements guide.
| Field | Required by 70E 130.5(H)? | Notes |
|---|---|---|
| Nominal system voltage | Yes | Use the voltage the study used |
| Arc flash boundary | Yes | Comes from the study or the PPE category table |
| Incident energy + working distance, or PPE category | Yes, at least one method | The two methods do not appear together on one label |
| Minimum arc rating of clothing / site-specific PPE | Permitted alternatives | Some programs list these as well |
| Limited and restricted approach boundaries | Not in the minimum list | Most labels include them anyway |
| Equipment ID, study date | Not in the minimum list | Expected by most safety programs and auditors |
The 2018 and later editions also put responsibility for documenting, installing and maintaining the label on the equipment owner, and they require the method and data behind the label to be documented.
Arc Flash Label Requirements by Edition: 2015, 2018, 2021, 2024
A lot of searches ask about a specific year, usually because a facility's program or a contract names one. The core content has stayed the same since 2015. Mostly the section numbers and the surrounding obligations changed. Check the edition your site and AHJ actually use.
| Edition | Section | What to know |
|---|---|---|
| NFPA 70E 2012 | 130.5(C) | Used the term hazard/risk category. Older labels often say HRC. |
| NFPA 70E 2015 | 130.5(D) | HRC renamed arc flash PPE category. Incident energy or PPE category, not both. |
| NFPA 70E 2018 | 130.5(H) | Same content. Added owner responsibility for the label and documentation of the method and data. |
| NFPA 70E 2021 | 130.5(H) | Same core content. Puts more weight on updating labels when the risk assessment review finds they are inaccurate. |
| NFPA 70E 2024 | 130.5(H) | Same core list. Check the current text for wording changes. |
| NEC 2017 and later | 110.16(B) | Added a separate field-marked label for larger service equipment: voltage, available fault current, clearing time, date. The scope has changed between editions. |
There is no separate 2020 or 2022 edition of NFPA 70E. A search for those years is usually looking for the 2021 edition or the 2020 NEC. OSHA does not prescribe the label content itself; it relies on general duty and consensus standards. That side is covered in our OSHA equipment labeling guide.
How to Read an Arc Flash Label
A technician should be able to read the label top to bottom and know what to wear and where to stand:
- Signal word (WARNING or DANGER): how serious the hazard is. Many programs switch to DANGER above about 40 cal/cm², where common arc-rated PPE runs out. That is program practice, not a fixed code number.
- Equipment ID: confirms you are at the gear the study modeled.
- Nominal voltage: sets the shock approach boundaries and the voltage-rated glove class.
- Arc flash boundary: anyone closer than this needs arc-rated PPE while the hazard exists.
- Incident energy at working distance: the heat you would be exposed to with your face and chest at that distance. Your PPE arc rating needs to meet or exceed it. If you work closer than the stated working distance, the exposure is higher than the label says.
- PPE category (if used instead): points to the PPE table in your program.
- Limited / restricted approach: shock boundaries for unqualified and qualified persons.
- Study date: if it is older than your review interval, treat the numbers as suspect.
Arc Flash Boundary Chart vs. Approach Boundary Table
People often mix these up. The arc flash boundary is calculated per piece of equipment in an incident energy study, or taken from the PPE category tables in 130.7(C)(15) when you use that method. No single plant-wide chart gives it.
The shock approach boundaries do come from a table based on voltage (130.4(E)(a) in recent editions; the number has moved over the years). Here are commonly cited values for the two most common AC classes. Verify them against your edition before engraving:
| Nominal voltage (AC) | Limited approach, fixed part | Restricted approach |
|---|---|---|
| 50 to 150 V (e.g. 120 V) | 3 ft 6 in | Avoid contact |
| 151 to 750 V (e.g. 208, 240, 480 V) | 3 ft 6 in | 1 ft 0 in |
Arc Flash Label Size Requirements
NFPA 70E does not set a minimum arc flash label size. NEC 110.21(B) expects field-applied hazard markings to warn effectively, be permanently affixed, and hold up in the environment. Its informational note points to ANSI Z535.4 for format and letter height. In practice the size follows how much text you have and how far away it has to be read:
| Plate size | Good fit for | Typical letter heights |
|---|---|---|
| 4 x 2 in | Panelboards, disconnects, small enclosures | Signal word 1/4 to 5/16 in; values 5/32 to 3/16 in |
| 5 x 3 in | MCCs, switchboards, VFD lineups | Signal word 3/8 to 1/2 in; values 3/16 to 1/4 in |
| 6 x 4 in and up | Switchgear, main services, labels with a PPE list | Signal word 1/2 in+; values 1/4 in+ |
These are practical suggestions, not code minimums. On a dim, crowded wall, go to the larger end. Engraved text does not rub off like printed ink, but it still has to be big enough to read from the working distance. Our engraved vs printed tags comparison covers where each holds up.
Arc Flash Label Template and Worked Example
Copy this field order and replace the example values with your own study numbers. This example uses the incident energy method only.
| Line | Field | Example value |
|---|---|---|
| 1 | Signal word header | WARNING |
| 2 | Hazard statement | ARC FLASH AND SHOCK HAZARD |
| 3 | Equipment ID | MCC-2, CUBICLE 4 |
| 4 | Nominal voltage | 480 VAC, 3-PHASE |
| 5 | Arc flash boundary | 42 IN |
| 6 | Incident energy | 8.2 CAL/CM² AT 18 IN |
| 7 | Limited / restricted approach | 3 FT 6 IN / 1 FT 0 IN |
| 8 | Study reference | ARC FLASH STUDY REV 2, 03/2026 |
Before anything is engraved, trace each number back to its source. Voltage and equipment ID come from the one-line, cross-checked against the nameplate. Arc flash boundary and incident energy come from the study output for that exact bus. Approach boundaries come from the study or the voltage table. The date comes from the report cover or revision log. The most common errors we see are a voltage copied off an old nameplate and an incident energy value with the wrong working distance next to it.
If you need a quick standard plate instead of a full custom layout, the 4x2 incident energy fill-in label has the field names engraved and blanks for your values. For larger gear, the 5x3 arc flash label leaves more room. Service equipment that also needs a fault current marking is covered in our NEC 110.24 available fault current guide.
When to Update the Label
NFPA 70E calls for the arc flash risk assessment to be reviewed at intervals of no more than 5 years, and sooner after major modifications. A changed utility transformer, breaker or fuse, trip setting, or conductor length can all change the numbers. Treat the date on the plate as a trigger: if the equipment changed and the label did not, the label no longer describes the panel in front of the technician.
Frequently Asked Questions
How do you read an arc flash label?
Start with the equipment ID to confirm you are at the right gear. Then check the voltage for shock protection, the arc flash boundary for where PPE starts, and the incident energy or PPE category for what to wear. If you will work closer than the stated working distance, the exposure is higher than shown. Last, check the study date, because an old date means the values may be stale.
Is there a minimum size for an arc flash label?
NFPA 70E does not set one. Many AHJs look for a label that is legible from where the work is done and durable for the environment, which commonly means 4x2 in for panelboards and 5x3 in or larger for MCCs and switchgear.
Can I put both incident energy and PPE category on the same label?
Since the 2015 edition, the label shows one or the other, not both. Choose the method your study supports and use it consistently across the facility.
Can values be filled in by hand or with a label maker?
NEC 110.21(B) generally does not allow handwritten hazard labels, but it does permit variable portions to be handwritten if they are legible. Many sites use engraved fill-in plates or fully engraved custom plates for durability. Check what your AHJ accepts.
Who decides between WARNING and DANGER?
Your electrical safety program or the engineer who did the study, usually based on an incident energy threshold. Around 40 cal/cm² is common practice, not a fixed requirement in every edition.
How often do arc flash labels need to be replaced?
Replace them whenever the study changes the values. The study itself is reviewed at least every 5 years under NFPA 70E, and sooner after equipment changes.
Send one equipment ID and the values from your study and we'll engrave a sample arc flash label and mail it, no charge.
Once the fields are right, ordering is quick. Start from the arc flash label builder, lay out a custom plate size in the rectangle lamacoid configurator, or request a free sample to see the material before you commit to a full equipment list.
Disclaimer. This article is provided for general informational purposes only and does not constitute legal, safety, or professional compliance advice. Regulations, standards, and codes are subject to change and may be interpreted differently by authorities having jurisdiction (AHJ). Always consult with qualified safety professionals, licensed engineers, or legal counsel to determine the specific requirements applicable to your facility. TagBuilder is not responsible for any actions taken based on this information.
UL, NFPA, NEC, ASME, CEMA, TIA, ANSI and OSHA are names or marks of their respective organizations; TagBuilder is not affiliated with or endorsed by any of them. Requirements above are paraphrased summaries, not the text of any standard. Always work from the current published edition and your AHJ.
