Arc Flash Labels for Solar Installations: NFPA 70E Requirements
Arc flash labels for solar installations are governed by NEC Section 110.16 and NFPA 70E Section 130.5(H). NEC 110.16(A) requires a general arc flash hazard warning on all energized equipment in non-dwelling locations. For service and feeder-supplied equipment rated 1,000A or more, NEC 110.16(B) requires a full NFPA 70E-compliant label with nominal system voltage, arc flash boundary, incident energy or PPE level, and date applied.
You finish a commercial solar installation - inverter, combiner boxes, AC disconnect, main service panel. The inspector shows up, walks to the service equipment, and asks where your arc flash label is. Not the general hazard sticker. The full NFPA 70E-compliant label with voltage, arc flash boundary, and incident energy. You don't have it. That's a fail - and now you need an arc flash study before you can re-label.
Arc flash labeling on solar jobs has gotten more specific with each NEC cycle. NEC 2023 tightened the threshold from 1,200A to 1,000A. NEC 2026 carried that forward and expanded the definition to include feeder-supplied equipment. If your solar installation connects to commercial-scale service equipment, you need to know exactly what goes on the arc flash label and who has to produce it. This article covers both the installation requirement (NEC 110.16) and the label content standard (NFPA 70E 130.5(H)) - because conflating the two is where most crews get tripped up.
What Is the NEC Requirement for Arc Flash Labels on Solar Equipment?
NEC Section 110.16 is split into two distinct tiers, and understanding which applies to your job changes everything about your labeling plan.
NEC 110.16(A) - General Arc Flash Warning: This applies to virtually all energized electrical equipment in non-dwelling locations that's likely to require service while energized. Switchboards, panelboards, industrial control panels, motor control centers. This includes inverters and combiner boxes on commercial solar installations. The requirement: a field or factory marking warning qualified persons of a potential arc flash hazard. A general "Warning: Arc Flash Hazard" label satisfies this tier.
NEC 110.16(B) - Full Arc Flash Label: This tier kicks in for service equipment and feeder-supplied equipment rated 1,000 amperes or more. At this threshold, a general warning is not enough. The label must be a full arc flash label per applicable industry practice - which means NFPA 70E Section 130.5(H) - and must include the date the label was applied.
The threshold dropped from 1,200A to 1,000A starting with NEC 2023 and remained at 1,000A in NEC 2026. If your solar installation feeds into service equipment at 800A, only 110.16(A) applies. At 1,000A or more, you're in 110.16(B) territory and need a full arc flash study to produce the label.
What Must Go on an NFPA 70E Arc Flash Label?
NFPA 70E Section 130.5(H) specifies the minimum content for an arc flash equipment label. Per the 2024 edition, the label must include:
- Nominal system voltage
- Arc flash boundary (the distance at which a person could receive a second-degree burn from incident energy)
- At least one of the following:
- Available incident energy and corresponding working distance - Minimum arc rating of required clothing - Site-specific level of PPE
The 2024 NFPA 70E also added that labels must be of sufficient durability for the environment involved - which mirrors NEC 110.21(B)'s durability standard. Outdoor service equipment in a solar yard needs a label rated for UV, moisture, and temperature swings. A paper printout won't survive one Arizona summer.
Does Every Inverter and Combiner Box Need an Arc Flash Label?
This is where crews often over- or under-comply. Here's the framework:
Residential solar (1- and 2-family dwellings): NEC 110.16 generally doesn't apply to dwelling units. Most residential solar installations don't require arc flash labels under the NEC. Some AHJs add their own requirements, so always check locally.
Commercial solar, inverters, and combiner boxes: If your inverter or combiner box is located in a non-dwelling setting and is likely to be serviced while energized, NEC 110.16(A) applies - you need at minimum a general arc flash warning label.
Service and feeder-supplied equipment at 1,000A+: If your solar installation ties into a main service or feeder-supplied switchboard rated 1,000A or more, NEC 110.16(B) applies. You need a full NFPA 70E arc flash label produced from an actual arc flash hazard analysis - not a generic sticker.
For most commercial rooftop solar installs, this means the inverters and DC combiner boxes get 110.16(A) labels, and the main service gear gets a 110.16(B) full arc flash label if it hits the 1,000A threshold.
Print Pro AZ carries general arc flash warning labels that satisfy 110.16(A) requirements. For 110.16(B) jobs requiring study-based labels, contact us about custom label production from your arc flash study data.
Who Has to Do the Arc Flash Study?
An arc flash study is an engineering analysis that calculates the incident energy at each piece of equipment, the arc flash boundary, and the required PPE. It's performed by a licensed electrical engineer using software modeling of your system's fault current, conductor impedances, and OCPD clearing times.
For most solar contractors, the path is:
- Design engineer of record or third-party electrical engineer performs the study
- Study results are used to produce NFPA 70E-compliant labels for each piece of equipment
- Labels are applied before system energization and before the 110.16(B) inspection requirement is triggered
If the study isn't done before inspection, you'll need to either derate to under the 1,000A threshold in your design (not always possible) or come back with labels after the study is complete.
What Does a Compliant Arc Flash Label Look Like?
A properly produced arc flash label includes the following fields, typically laid out in a table format:
| Field | Example |
|---|---|
| Nominal System Voltage | 480V |
| Arc Flash Boundary | 4.2 feet |
| Incident Energy | 8.3 cal/cm² at 18 inches |
| Required PPE | Arc Rating 8 cal/cm² minimum |
| Date of Analysis | 2026-01-15 |
| Equipment ID | Main Switchboard MDP-1 |
Label materials must meet NFPA 70E 130.5(H)'s durability requirement. For outdoor service equipment, Print Pro AZ uses UV-stable polycarbonate rated for outdoor exposure. Indoor switchgear labels can use polyester.
Note: NEC 110.16(B) specifically requires the date the label was applied to be on the label. This is separate from the date of the arc flash analysis (though many labels include both). Don't skip the date - it's one of the first things an inspector checks.
FAQ
Does every solar installation need an arc flash label?
Residential (dwelling unit) installations are generally exempt from NEC 110.16. Commercial solar installations in non-dwelling settings need a general arc flash warning per 110.16(A) on energized equipment likely to be serviced while energized. Installations tied to service or feeder equipment at 1,000A or more need a full NFPA 70E label per 110.16(B).
What's the difference between an arc flash warning label and an arc flash label?
A warning label (NEC 110.16(A)) is a general hazard notification - it says arc flash hazard is present. An arc flash label (NEC 110.16(B), per NFPA 70E 130.5(H)) contains specific engineering data: system voltage, arc flash boundary, incident energy, PPE requirements, and date applied. The full label requires an arc flash study.
Who produces the arc flash label data?
A licensed electrical engineer performs the arc flash hazard analysis and produces the study data. That data is then used to print NFPA 70E-compliant labels for each piece of equipment. The contractor typically applies the labels before system energization.
Do I need a new arc flash study if I add storage to an existing solar installation?
Yes. Adding an energy storage system changes the fault current contribution of the system, which changes the incident energy calculations. Any significant change to a system that already has arc flash labels should trigger a re-study and updated labels.
Can I handwrite the date on an arc flash label?
No. NEC 110.21(B) requires that field-applied markings be durable for the environment. Handwritten dates can fade, smear, or become illegible. Use a printed or engraved date. Print Pro AZ can produce custom arc flash labels with your study data pre-printed.
3 Key Takeaways
- Two-tier system: NEC 110.16(A) requires a general arc flash warning on all commercial solar equipment likely to be serviced while energized. NEC 110.16(B) requires a full NFPA 70E label on service and feeder equipment rated 1,000A or more.
- An arc flash study is required to produce the data for a 110.16(B) label. A generic sticker is not enough on equipment over 1,000A.
- The date the label was applied is required under NEC 110.16(B). Build the date into your printed label - don't handwrite it.
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