Guide · Labels
Arc flash label requirements: what the 2026 NEC now asks for
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Arc flash label requirements come from three places. The 2026 NEC, in section 110.16, now requires arc-flash hazard marking on service and feeder equipment of any rating, other than in dwelling units. NFPA 70E-2027 sets what the label must show. OSHA enforces the warning duty. The values on every label come from an arc flash study.
Why now
Why label questions are landing on your desk
The 2026 NEC is being adopted
States are moving to the 2026 edition. Texas applied it from 1 September 2026. New and modified equipment is inspected against it.
The 1000 A threshold is gone
Equipment below 1000 A that never needed the detailed marking under the 2023 NEC can need it now.
NFPA 70E-2027 is in force
Label content and the 5-year review now follow the 2027 edition of the standard.
2026 NEC arc flash label requirements
The 2026 NEC renamed section 110.16 Arc-Flash Hazard Marking and merged its two parts. Service and feeder equipment outside dwelling units must carry a permanent marking that states four things: the system voltage, how far the arc flash boundary reaches, either the incident energy available or the minimum PPE level, and when the arc flash assessment was done.
| Item | 2023 NEC | 2026 NEC |
|---|---|---|
| Equipment covered | Service and feeder-supplied equipment rated 1000 A or more | Service and feeder equipment of any rating, other than dwelling units |
| Label content | Per applicable industry practice, with the date the label was applied | Nominal voltage, arc flash boundary, incident energy or minimum PPE, assessment date |
| Date on the label | Date the label was applied | Date the arc flash assessment was completed |
| Section title | Arc-flash hazard warning | Arc-flash hazard marking |
NEC 110.16 arc flash hazard marking, who applies it
The marking can be applied in the factory or in the field, but the values depend on your installed system, so in practice they come from an arc flash study. The installer or owner applies the label before the equipment is energized for use. Your local inspector enforces the edition your state or city has adopted, so confirm it first.
NFPA 70E arc flash label requirements
NFPA 70E-2027 requires equipment labels that show the nominal voltage, the arc flash boundary and at least one of: incident energy with its working distance or the PPE category, the minimum arc rating of clothing, or the site-specific level of PPE. Incident energy and PPE category must not appear together, so the two methods are never mixed.
| Field | Required by NFPA 70E-2027 |
|---|---|
| Nominal voltage | Yes |
| Arc flash boundary | Yes |
| Incident energy with working distance | One of these: incident energy or PPE category (not both), minimum arc rating, or site-specific PPE |
| Available fault current and clearing time | Not required on the label; recorded in the study |
OSHA arc flash label requirements
OSHA has no rule that spells out arc flash label content. 29 CFR 1910.335(b) requires employers to warn workers of electrical hazards with signs, tags and barricades, and OSHA points to NFPA 70E-2027 as the recognized way to do it. An inspector who finds no labels, or labels that do not match the system, can cite the employer.
The 2026 NEC widened who needs labels. Check yours before the inspector does.
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Label size, format and what not to put on it
No code sets a minimum label size. The label must be legible at the working position, durable for its environment and permanently fixed, and most follow the ANSI Z535.4 safety sign format. Leave off what the rules exclude or no longer ask for: incident energy and PPE category together, and handwritten values.
Key takeaways for the plant team
- The 2026 NEC removed the 1000 A threshold: service and feeder equipment of any rating needs the marking.
- The 2026 label carries voltage, arc flash boundary, incident energy or minimum PPE, and the assessment date.
- NFPA 70E-2027 sets label content; never show incident energy and PPE category together.
- OSHA enforces the warning duty and treats NFPA 70E-2027 as the recognized method.
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We calculate the values, print labels that meet the 2026 NEC and NFPA 70E-2027, and fix them to your gear. Each label traces back to a model reviewed by a US-licensed Professional Engineer. The fixed quote arrives within 24 hours.
Frequently asked questions
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What are the new arc flash label requirements in the 2026 NEC?
The 2026 NEC requires arc-flash hazard marking on service and feeder equipment of any rating, other than in dwelling units. Each label gives four items: the system voltage, the reach of the arc flash boundary, either the incident energy available or the minimum PPE level, and when the arc flash assessment was done.
Does NEC require arc flash labels?
Yes. NEC section 110.16 requires arc flash marking on electrical equipment likely to need examination, adjustment, servicing or maintenance while energized. The 2026 edition extends the detailed marking to all non-dwelling service and feeder equipment. Which edition applies depends on what your state or city has adopted.
Are arc flash labels required by OSHA?
Not by a specific OSHA rule on label content. OSHA requires employers to warn workers of electrical hazards and to protect them, and it recognizes NFPA 70E-2027 labeling as the way to do that. In an inspection, missing or wrong labels support a citation under the general rules.
Which items are not required on an arc flash warning label?
Available fault current and protective device clearing time are not required on the 2026 NEC marking, though they belong in the study. Under NFPA 70E-2027, incident energy and PPE category must not both appear. Shock approach boundaries are often added for convenience but are not required label fields.
Do existing labels need replacing under the 2026 NEC?
Not automatically. The NEC applies to new installations and modifications, so new or changed service and feeder equipment must meet the 2026 rule. Existing labels should still match the current study, and the next update is the right moment to bring every label into line.
How big does an arc flash label need to be?
No code sets a size. The label must be legible from where the worker stands, durable for heat, washdown or sunlight, and permanently attached. Most labels follow the ANSI Z535.4 format with a signal word header, and we size them to the equipment door they go on.
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