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SESK: Stuff Everyone Should Know · sesk.info/elec-arc-flash-label-110-16

The 2026 NEC removed which threshold from the arc flash marking rule in 110.16?

The 1,000A threshold is gone in 110.16.

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  1. The 600 volt rating
  2. The 1,000 ampere rating ✔
  3. The 3-phase requirement

Why: Arc flash warning labels used to be required only on equipment rated 1,000A or more. The 2026 NEC removed that cutoff, so all non-dwelling service and feeder equipment needs marking.

Huh, didn't know that: The rule covers switchboards, enclosed panelboards and meter socket enclosures that are not in dwelling units.

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References

Answer: The 1,000 ampere rating. Arc flash warning labels used to be required only on equipment rated 1,000A or more. The 2026 NEC removed that cutoff, so all non-dwelling service and feeder equipment needs marking.

  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
    The previous Code only required arc flash warning labeling of service and feeder equipment of 1,000A or more.
    Checked 2026-10-10.
  2. EC&M: Key Changes to the '26 NEC www.ecmweb.com/neca-show-coverage/article/55404442/key-changes-to-the-26-nec
    all non-dwelling unit service and feeder equipment will require arc flash marking.
    Checked 2026-10-10.

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