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SESK: Stuff Everyone Should Know · sesk.info/solar-dc-arc-persistent

According to NREL, how does an arc fault in DC wiring compare with one in AC wiring?

It is more persistent in DC wiring.

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  1. It is more persistent in DC wiring ✔
  2. It is weaker and stops by itself
  3. Arcs cannot happen in DC wiring

Why: AC current drops to zero many times each second, which helps an arc go out. DC never does, so a DC arc can keep burning. Loose solar connections are a real fire concern.

Huh, didn't know that: NREL says electricians on live DC circuits need arc-rated clothing, insulation gloves and a face shield.

The dad joke
DC arcs are the guests who never know when to leave.
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References

Answer: It is more persistent in DC wiring. AC current drops to zero many times each second, which helps an arc go out. DC never does, so a DC arc can keep burning. Loose solar connections are a real fire concern.

  1. NREL: Best Practices for O&M of PV and Energy Storage Systems, 3rd ed. (2018) docs.nlr.gov/docs/fy19osti/73822.pdf
    An arc fault is more persistent in DC wiring than in AC wiring.
    Checked 2026-10-10.

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