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SESK: Stuff Everyone Should Know · sesk.info/elec-fault-current-label-408-6

The 2026 NEC 408.6 requires what to be field marked on panelboards outside one- and two-family dwellings?

Mark available fault current and the date it was calculated.

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  1. Available fault current and the calculation date ✔
  2. The installer's license number
  3. The panel's purchase price

Why: New 2026 rules in 408.6 require the available fault current and the date it was calculated to be marked on the panel. This applies everywhere except one- and two-family dwellings.

Huh, didn't know that: Fault current marking helps confirm that equipment ratings are high enough for the system.

The dad joke
Why did the panelboard keep a diary? It wanted every fault on record.
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References

Answer: Available fault current and the calculation date. New 2026 rules in 408.6 require the available fault current and the date it was calculated to be marked on the panel. This applies everywhere except one- and two-family dwellings.

  1. EC&M: Top 25 Changes to the 2026 NEC ecmweb.com/national-electrical-code/article/55330438/top-25-changes-to-the-2026-national-electrical-code
    Available fault current and the date the calculation was performed must be field marked.
    Checked 2026-10-10.

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