CODE UPDATE · NEC 110.16
The 2026 NEC Expands Arc Flash Labeling to Nearly All Commercial Equipment
The 1,000-ampere threshold is gone, and the label now has to carry an assessment date — which quietly turns a labelling requirement into a study-and-documentation project.
The 2026 NEC removed the 1,000-ampere threshold from section 110.16. Arc flash labelling now applies to distribution equipment in non-dwelling installations generally — switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures and motor control centres — and the label must state the date the arc flash assessment was determined.
That last clause is the one that turns a labelling requirement into a project. A label carrying an incident energy figure and an assessment date is the visible output of a study. If no study exists, no compliant label can be produced.
THE SHORT VERSION
110.16 — threshold removed. Detailed arc flash labelling is no longer limited to equipment rated 1,000 A and above in non-dwelling installations.
The label needs a date. It must state when the arc flash assessment was determined, which means a study has to exist behind it.
408.6 is the companion rule. Available fault current and short-circuit current rating must now be field-marked on switchboards and panelboards.
Sequence matters. Fault current first, then interrupting ratings, then the study, then labels and PPE. Buying PPE before the study is buying a guess.
What changed in 110.16
Previous editions required detailed arc flash labelling — voltage, boundary, incident energy or PPE category — on service equipment rated 1,000 A and above. Below that threshold, a general warning label was sufficient in most cases.
The 2026 edition drops the threshold for non-dwelling installations. The detailed marking requirement now reaches equipment that previously carried only a generic caution.
| Previous editions | 2026 NEC | |
|---|---|---|
| Equipment in scope | Service equipment rated 1,000 A and above | Distribution equipment in non-dwelling installations generally |
| Below the threshold | A general warning label was sufficient in most cases | No threshold — detailed marking reaches equipment that carried only a generic caution |
| Assessment date on the label | Not required | Required — the date the arc flash assessment was determined |
What the label must state
- Nominal system voltage
- Arc flash boundary
- Available incident energy and the corresponding working distance, or the required arc flash PPE category
- The date the arc flash assessment was determined
The alignment is with NFPA 70E, which has required assessment-based labelling for years. What the 2026 NEC does is close the gap between the installation code and the safe work practices standard.
The companion requirement most people miss: 408.6
New section 408.6 requires field marking of the available fault current and the short-circuit current rating on switchboards and panelboards in non-dwelling installations.
These two requirements are related in a way worth spelling out. Available fault current is the input to an arc flash study. It is also the number that determines whether the overcurrent devices inside the enclosure comply with 110.9, which requires an interrupting rating at least equal to the fault current available at the line terminals.
ONE MARKING, THREE JOBS
Field-marking fault current satisfies 408.6, documents the input to the 110.16 label, and exposes any equipment whose devices were sized against a fault current that no longer applies.
That third effect is not hypothetical. Service upgrades, utility transformer changes and added distributed generation all move available fault current, and the overcurrent devices downstream rarely get revisited.
Working space: 110.26 clarified
Working space requirements were tightened in a way that matters for equipment selection and layout rather than paperwork. Obstruction of access and egress is now evaluated with equipment doors open at 90 degrees — the realistic worst case during work, rather than the condition when the panel is closed.
Requirements for enclosed live parts are stated explicitly. For anyone laying out a mechanical room or an electrical closet, this is a design-stage constraint, not a field fix.
What a facility should actually do
In order, because the sequence saves money.
Establish available fault current
From a short-circuit study, or from the utility. Everything downstream depends on this number, and guessing it produces a compliant-looking label that documents nothing.
Check interrupting ratings against it
Under 110.9, devices must be rated for the fault current available at their terminals. Legacy equipment is where this fails — see our industrial fuse selection guide for why a 10 kA Class H fuse in a modern service is a live code violation nothing on the panel announces.
Commission or refresh the arc flash study
The label needs an incident energy figure and an assessment date. An old study with no date on the label does not satisfy the new marking requirement.
Produce and apply labels
Durable, legible, appropriate to the environment.
Match PPE and safety equipment to the results
The study determines the category. Buying PPE before the study is buying a guess.
THE COMMON FAILURE
Doing steps 4 and 5 before steps 1 to 3. It produces labels that will not survive an audit and PPE that may not match the hazard.
The OSHA dimension
The NEC is an installation code. OSHA enforces workplace safety, and its electrical standards reference the hazard assessment and protective equipment obligations that arc flash labelling supports.
A facility preparing for an inspection with a gap list and a fixed date has a specific procurement problem: the whole list quoted as one package, items rated correctly for their environment rather than merely available, and the ratings documentation supplied with the order rather than assembled afterwards from packaging.
Substituting a lower-rated item because it ships sooner is how a corrected finding becomes a repeat finding.
Frequently asked questions
What changed for arc flash labels in the 2026 NEC?
Section 110.16 no longer limits detailed arc flash labelling to equipment rated 1,000 A and above in non-dwelling installations. Switchboards, switchgear, enclosed panelboards, industrial control panels, meter socket enclosures and motor control centres are now in scope generally. Labels must state nominal system voltage, the arc flash boundary, available incident energy or required PPE, and the date the arc flash assessment was determined.
Does every panel need an arc flash label now?
The expanded requirement applies to distribution equipment in non-dwelling installations. Dwelling units are treated differently. Because the scope depends on equipment type and occupancy, and because state amendments can modify adopted code, confirm the requirement for your specific installation against the code text as adopted in your jurisdiction and with the authority having jurisdiction.
What is the difference between 110.16 and 408.6?
Section 110.16 governs arc flash warning labels and what they must state. New section 408.6 requires field marking of available fault current and short-circuit current rating on switchboards and panelboards in non-dwelling installations. They are complementary: available fault current is an input to the arc flash study that produces the 110.16 label, and it is also the figure that determines whether overcurrent devices satisfy the interrupting rating requirement in 110.9.
Do arc flash labels expire?
The NEC does not set an expiry in the way a calibration certificate does, but the 2026 requirement to state the assessment date makes the label’s age visible. An assessment reflects a specific system configuration, so it stops being accurate when that configuration changes — a service upgrade, a utility transformer replacement, added generation or storage, or significant changes to protective device settings. Treat any of those as a trigger to revisit the study.
Who is responsible for arc flash labelling?
Responsibility generally sits with the equipment owner or the employer operating the facility, since the label reflects an assessment of the installed system rather than a manufacturer’s product rating. In practice the study is performed by a qualified engineer, the labels are produced from its results, and the installing contractor applies them. Confirm the allocation in your contract documents — it is a common source of dispute at closeout.
Sourcing the equipment and documentation
ATEK Distribution supplies industrial safety equipment, job site safety equipment, power distribution equipment and circuit breakers to contractors, facilities and government buyers nationwide from Minneapolis.
Send a gap list or an equipment schedule and we will quote it as one package with ratings stated per line.
RELATED READING
For the wider set of 2026 code changes affecting procurement, see what changed in the 2026 NEC. For the EV charging side of Article 625, see EV charging under the 2026 NEC.