Answer Capsule: NEC 2023 electrical labeling changes affect Articles 110, 408, 690, and 705. Key updates include outdoor labels that must be mechanically fastened (Section 110.21(B)), arc flash labels required on equipment rated 1,000A or more (Section 110.16(B)), physical location added to panel source markings (Section 408.4(B)), and new DC voltage labels for PV systems (Section 690.7(D)).
You pulled your permit, roughed in the job, and now the inspector is standing in front of your panel with a red pen. The labels are wrong. Not the wiring. The labels. That scenario plays out on job sites every week across the country, and it is almost always avoidable. NEC 2023 electrical labeling requirements shifted in ways that catch even experienced crews off guard, especially on commercial, solar, and mixed-source installations. This post breaks down exactly what changed from NEC 2020 to NEC 2023, which code sections apply, which states are now enforcing the new edition, and what your labels need to say, show, and be made of to pass inspection the first time.
What Are the Biggest NEC 2023 Labeling Changes You Need to Know?
The biggest shifts in NEC 2023 electrical labeling fall into four categories: outdoor label durability, arc flash thresholds, panel source identification, and solar PV markings. Each change targets a real failure mode inspectors have been flagging for years.
Here is a plain-English breakdown of what changed and why it matters to your next inspection.
Section 110.21(B): Outdoor Labels Must Now Be Mechanically Fastened
Under NEC 2020, outdoor labels were required to be durable and weather-resistant. NEC 2023 tightened that language significantly. Per NEC 2023 Section 110.21(B), any field-applied hazard marking installed outdoors must be permanently affixed using screws, bolts, or rivets. Adhesive-only labels do not meet the requirement for outdoor equipment.
The intent is simple: adhesive labels peel in Phoenix heat, Florida humidity, and Pacific Northwest rain. The code now requires that the label physically cannot fall off. If you are applying labels to outdoor disconnects, combiner boxes, or exterior service equipment, the label must be mechanically fastened or engraved.
Inspection Tip: Bring stainless steel or aluminum screw-mount label holders to any outdoor service or solar job. An adhesive-backed polycarbonate label that passes in a conditioned interior space will not satisfy 110.21(B) on an exterior disconnect. Print Pro AZ carries solar electric tags formatted for exterior installations.
Does NEC 2023 Change the Arc Flash Label Requirement?
Yes, and the threshold dropped. Per NEC 2023 Section 110.16(B), arc flash warning labels are now required on service equipment and feeder-supplied equipment rated 1,000 amperes or more in non-dwelling occupancies. NEC 2020 set that threshold at 1,200 amperes.
That 200-amp difference may not sound like much, but it pulls a large number of commercial distribution panels into scope that were not previously covered. If you are wiring a mid-size retail strip, a school, or a light industrial facility with gear in the 1,000A to 1,200A range, you now owe those panels an arc flash label.
The label must be field-applied before energizing and must convey enough information for safe work planning and PPE selection. The language in 110.16(B) also added "feeder-supplied equipment" to the section title, meaning downstream switchgear and distribution boards fed by a feeder circuit, not just the main service, now carry the same requirement.
When your crew is ordering labels for a commercial build, check the service and feeder equipment ratings carefully. Print Pro AZ stocks electrician labels that meet the durability and marking requirements of 110.16(B) for both service and feeder-supplied gear.
What Did NEC 2023 Change in Article 408 for Panel Labeling?
Two things changed in Article 408, and both affect how you label panelboards on commercial work.
408.4(A): Circuit directory specifics. Labels must appear directly at each switch or circuit breaker. For panelboards, the circuit directory must be placed on the face of the panel door, inside the door, or at an approved adjacent location. Any abbreviations or symbols used in circuit labeling must be explained somewhere on or with the directory. If your crew uses shorthand like "RTU-1" without a legend, that is a 408.4(A) violation.
408.4(B): Physical location of power source. This is the bigger change. NEC 2023 rewrote Section 408.4(B) to require that panelboards, switchboards, and switchgear supplied by a feeder must be marked with the source of supply AND the physical location of that source. Under NEC 2020, identifying the source panel was enough. Under NEC 2023, you must also state where that source panel lives.
For example, "Fed from MDP" is no longer sufficient. The label now needs to read something like "Fed from MDP - Electrical Room 101, 1st Floor." On multi-story commercial projects, this addition is significant. Make sure your panel schedules and label orders reflect this before you pull your inspection.
What Solar PV Labeling Changed in NEC 2023?
NEC 2023 made three labeling changes in Article 690 that affect every solar installation.
Section 690.7(D): New DC voltage label. This section is entirely new. It requires a permanent, readily visible label showing the highest maximum DC voltage in the PV system. The label must be placed at the DC disconnecting means, the inverter, or associated distribution equipment. This label did not exist as an explicit requirement in NEC 2020. If your system design hits a high DC voltage point, that number needs to be on a label and it needs to be visible.
Section 690.12(D): Rapid shutdown label format changed. The rapid shutdown label was previously governed by Section 690.56(C). In NEC 2023 it was relocated to Section 690.12(D)(2). More importantly, the old requirements for a specific black-and-yellow color scheme and 3/16-inch minimum supporting text were removed. The label still must include a simple roof outline diagram and the words "SOLAR PV SYSTEM IS EQUIPPED WITH RAPID SHUTDOWN," but it no longer requires three colors on reflective stock. A high-contrast thermal transfer label (white on red, or black on yellow) now satisfies the code.
Section 690.31(B)(2): DC conductor polarity identification. Positive conductors must be marked with "+", "POSITIVE", or "POS." Negative conductors must be marked with "-", "NEGATIVE", or "NEG." This applies at all termination, connection, and splice points. Tape, heat shrink, or labeling all satisfy the requirement as long as the marking is durable. Colored wire alone is not sufficient if the color code is not also identified.
Print Pro AZ offers solar label bundle packs that include rapid shutdown labels, DC voltage markers, and polarity identification labels formatted to NEC 2023 requirements.
| Code Section | NEC 2020 Requirement | NEC 2023 Requirement |
|---|---|---|
| 110.21(B) Outdoor Labels | Durable and weather-resistant | Must be mechanically fastened (screws, bolts, or rivets) |
| 110.16(B) Arc Flash | Required at 1,200A and above | Required at 1,000A and above, adds feeder-supplied equipment |
| 110.20 Reconditioned Equipment | Limited requirements | New section; GFCIs and AFCIs cannot be reconditioned; field label required |
| 408.4(A) Circuit Directory | Label at each overcurrent device | Label at each device plus abbreviation legend required |
| 408.4(B) Source Marking | Identify power source | Must include physical location of source |
| 690.7(D) Max DC Voltage | Not explicitly required | New permanent label required |
| 690.12(D) Rapid Shutdown | In 690.56(C); black/yellow required | Relocated; color and size requirements relaxed |
| 690.31(B)(2) Polarity | General identification required | Explicit +/POS and -/NEG marking required |
| 705.10 Multiple Sources | Scattered references | Consolidated; "label" added as approved marking type; emergency phone number required |
What Did NEC 2023 Change About Multiple-Source Power Identification?
Section 705.10 was rewritten and consolidated. In NEC 2020, requirements for identifying multiple power sources (solar + utility, generator + solar, etc.) were spread across several articles. NEC 2023 pulled them together into Section 705.10 as the single reference point for power source identification labels.
The key additions in 705.10 include: the word "label" was formally added as an approved marking method alongside placards and directories, and a new requirement was added for the label to include emergency telephone numbers for any off-site entities servicing the power source systems. The required text "CAUTION: MULTIPLE SOURCES OF POWER" remains.
That phone number requirement is new and easy to overlook. If a utility or third-party monitoring company services the system, their emergency contact information must appear on the permanent label at each service equipment location.
Real Scenario: A solar-plus-storage installation with a utility interconnect now requires a 705.10 label that states "CAUTION: MULTIPLE SOURCES OF POWER," lists disconnecting means locations for all sources, and includes the utility's emergency contact number. If your label was ordered before 2023 NEC adoption in your state, it likely does not include the phone number field. Print Pro AZ can provide updated 705.10 label sets that include a writable emergency contact field.
Which States Are Enforcing NEC 2023 Right Now?
As of early 2026, approximately 17 states have officially adopted NEC 2023. The following states are among those enforcing the 2023 edition: Alabama, Alaska, Arkansas, California, Connecticut, Delaware, Florida, Georgia, Hawaii, Iowa, Louisiana, Montana, New Hampshire, New Mexico, North Carolina, North Dakota, Rhode Island, South Carolina, South Dakota, Vermont, and Virginia. New York began transitioning to the 2023 edition in late 2025.
About 21 states are still on NEC 2020 as of the same period. Six states remain on NEC 2017, and a small number have not adopted past NEC 2008. Adoption status changes at the state and local level, so the safest move is always to verify with your local authority having jurisdiction (AHJ) before submitting for permit.
For contractors working across state lines, this creates a real compliance challenge. Your label package for a job in California must meet NEC 2023 requirements. The same job in Pennsylvania may still be evaluated against NEC 2020. Keeping two separate label kits stocked, or using a kit built to the stricter 2023 standard for all jobs, is the cleanest approach.
The NFPA publishes current adoption status at nfpa.org. Check it before assuming which edition governs your job.
Critical Rule: Even in states that have not yet adopted NEC 2023, local jurisdictions can and do adopt newer editions independently. Always confirm with the AHJ, not just the state code office.
Related reading: OSHA Pipe Marking Requirements: General Duty Clause Risk
Frequently Asked Questions
What labeling changes does NEC 2023 require for outdoor electrical equipment?
Per NEC 2023 Section 110.21(B), all field-applied hazard labels on outdoor equipment must be permanently affixed using mechanical fasteners such as screws, bolts, or rivets. Adhesive-only labels no longer satisfy this requirement for outdoor installations. This applies to exterior disconnects, combiner boxes, service equipment, and any other outdoor gear requiring a hazard marking.
Does NEC 2023 change what needs to be on a rapid shutdown label?
Yes. NEC 2023 moved the rapid shutdown label requirement from Section 690.56(C) to Section 690.12(D)(2) and removed the specific black-and-yellow color requirement and 3/16-inch text size requirement. The label still must include a roof outline diagram and the words "SOLAR PV SYSTEM IS EQUIPPED WITH RAPID SHUTDOWN," but it can now be printed in any high-contrast color combination.
At what amperage is an arc flash label required under NEC 2023?
Under NEC 2023 Section 110.16(B), arc flash labels are required on service equipment and feeder-supplied equipment rated 1,000 amperes or more in non-dwelling occupancies. This is a reduction from the 1,200-ampere threshold in NEC 2020, bringing more commercial distribution equipment into the arc flash labeling requirement.
What must a panelboard source label include under NEC 2023?
Per NEC 2023 Section 408.4(B), the source label on a panelboard, switchboard, or switchgear supplied by a feeder must identify both the power source and the physical location of that source. Stating "Fed from MDP" is no longer sufficient. You must also indicate where MDP is physically located in the building.
Do I need to use NEC 2023 label requirements if my state has not adopted NEC 2023 yet?
No, but it depends on your jurisdiction. If your state is still on NEC 2020, that edition governs your permit. However, individual cities or counties may have adopted NEC 2023 independently. Always verify the enforced edition with the local AHJ before ordering labels for a job. When in doubt, labeling to the stricter NEC 2023 standard protects you in any jurisdiction.
3 Takeaways and Next Steps
- Outdoor labels changed. NEC 2023 Section 110.21(B) requires mechanical fasteners, not just adhesive, for any field-applied label on exterior equipment. If your crew is still peeling and sticking labels on outdoor gear, you are failing that inspection.
- The arc flash threshold dropped. Section 110.16(B) now covers equipment at 1,000A and above. Check your gear ratings on every commercial job. Feeder-supplied distribution equipment is now explicitly in scope.
- Solar PV labeling has three new requirements. Max DC voltage (690.7(D)), revised rapid shutdown label format (690.12(D)), and explicit conductor polarity marking (690.31(B)(2)) are all changes from NEC 2020 that your label kit needs to address.
Print Pro AZ builds label packs specifically to NEC 2023 requirements so your crew does not have to figure out which sticker goes where. Every pack is designed around the exact code sections listed above.
Shop our NEC 2023 compliant solar label packs
Also available:
- Electrician label sets for commercial and residential work
- Bundle packs for full solar installations
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.
Last Updated: 2026-10-05
This article is part of the Print Pro AZ NEC labeling series. Start with the pillar guide: The National Electrical Code Explained.
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