*Covers NEC 408.6 in the 2020, 2023 and 2026 editions. Checked November 2026. Written by Panel Label Company in Clayton, NC. Our founder spent 13 years in commercial construction as a project manager and superintendent.*
Outside one- and two-family homes, every switchboard, switchgear lineup and panelboard needs a field-applied label showing the available fault current and the date it was calculated. That's NEC 408.6, and it has been in the code since at least the 2020 edition. The 2026 edition adds the equipment's short-circuit current rating (SCCR) to the label and asks for the numbers to be rechecked when the system changes.
This label is easy to miss because people associate fault current marking with the service. NEC 110.24 covers the service equipment. 408.6 carries the same idea to the panels downstream, so each one shows what it could see in a fault. We engrave these as custom engraved electrical panel labels.
What 408.6 requires
In every edition, switchboards, switchgear and panelboards must have a short-circuit current rating at least as high as the available fault current. For equipment outside one- and two-family dwellings, all three editions also require:
- The available fault current, field marked on the enclosure at the point of supply.
- The date the calculation was performed, on the same marking.
- A durable marking. In 2020 and 2023 it has to meet 110.21(B)(3), which requires a label durable enough for the environment it's in. The 2026 edition points to all of 110.21(B).
The code doesn't say who performs the calculation. On most commercial jobs the number comes from the engineer of record or the electrical contractor, starting from the utility's available fault current and the one-line diagram. We don't calculate fault current; we engrave the values you provide.
What changed in each edition
| What 408.6 requires (outside one- and two-family dwellings) | 2020 NEC | 2023 NEC | 2026 NEC |
|---|---|---|---|
| SCCR at least equal to the available fault current | Yes | Yes | Yes |
| Available fault current field marked on the enclosure | Yes | Yes | Yes |
| Date of the calculation on the marking | Yes | Yes | Yes |
| Marking durable for its environment | Yes, 110.21(B)(3) | Yes, 110.21(B)(3) | Yes, 110.21(B) |
| Equipment SCCR field marked, based on the breakers installed | Not in 408.6 | Not in 408.6 | Yes |
| Available fault current documented for inspectors and maintenance | Not in 408.6 | Not in 408.6 | Yes |
| Recheck the value when changes affect the fault current | Not in 408.6 | Not in 408.6 | Yes |
Which edition applies depends on your state and any local amendments. As of our last check, North Carolina, South Carolina and Virginia enforce the 2020 NEC and Georgia enforces 2023. See our NEC adoption by state tracker for your state, and confirm local amendments with your inspector.
408.6 vs 110.24
| NEC 110.24 | NEC 408.6 | |
|---|---|---|
| Equipment covered | Service equipment | Switchboards, switchgear and panelboards |
| Buildings | Other than dwelling units | Other than one- and two-family dwellings |
| What gets marked | Available fault current and date of calculation | Available fault current and date of calculation (plus SCCR in 2026) |
| Where | On the service equipment | On each enclosure, at its point of supply |
In practice, a commercial job needs a fault current label at the service and on each switchboard and panelboard downstream. Our fault current labeling guide covers the service equipment side. The same equipment usually needs arc flash labels under NEC 110.16 as well, and we make those too.
What to put on the label
Keep it short and easy to read at arm's length:
| Line | Example |
|---|---|
| Header | AVAILABLE FAULT CURRENT |
| Value | 22,000 A (22 kA) |
| Date | CALCULATED: 10/15/2026 |
| SCCR (2026 edition, or if your spec asks) | SCCR: 65 kA @ 480V |
Use the panel's name from the one-line diagram so the label matches the drawings, and keep the calculation on file. When the utility transformer, the service or a feeder changes, the number can change too. Order a new label with the new value and date. Feeder-fed panels also need a source of supply label under NEC 408.4(B), and both labels often go on the same panel.
Material and ordering
The code asks for durability, not a specific material. Engraved acrylic is cut into the plate, so the numbers can't rub off, and it can be screwed on where adhesive isn't allowed. Industrial vinyl is an option where your spec allows adhesive labels.
| Size | Fits | Price each |
|---|---|---|
| 3" x 2" | Value and date | $6.30 |
| 4" x 2" | Value, date and SCCR | $7.10 |
There's no minimum order, and most orders ship in 1-2 business days from Clayton, NC. Labeling a whole building? Upload your panel list with the values as an Excel or CSV file.
Design your fault current labels
FAQ
Does every panelboard need an available fault current label? Outside one- and two-family dwellings, yes. Since the 2020 edition, 408.6 requires the available fault current and the calculation date to be field marked on switchboards, switchgear and panelboards, not just the service.
Is 408.6 the same as 110.24? No. 110.24 covers service equipment. 408.6 covers switchboards, switchgear and panelboards, each marked at its own point of supply. Most commercial jobs need both.
Who calculates the available fault current? The code doesn't say. It usually comes from the engineer of record or the electrical contractor, starting from the utility's figure and the one-line diagram. We engrave the values you give us.
Does a house need this label? No. One- and two-family dwellings are excluded from the 408.6 marking requirement.
What changed in the 2026 NEC? The 2026 edition adds a field-marked SCCR based on the breakers installed, asks for the available fault current to be documented for inspectors and maintenance staff, and requires it to be rechecked when changes affect it.
Sources
- NFPA 70, National Electrical Code, section 408.6, 2020, 2023 and 2026 editions, reviewed through NFPA's free access program at nfpa.org
- NFPA Tentative Interim Amendment 23-12 to NEC 2023, section 408.6
- EC&M: TIA regarding section 408.6