Spot the Violation

ElectricalGFCI, AFCI & receptacle devicesLevel 32023 NEC

Two-prong swap in an old house

Painted plaster living room wall above an oak baseboard and hardwood floor. A new white three-prong receptacle marked TR has been pulled out of an old steel box set in the plaster. The box is fed by one cloth-braided cable carrying only a black and an aged white rubber-insulated conductor: black on a brass screw, white on a silver screw, and the green grounding screw empty. An old brown two-prong receptacle and plate and a screwdriver lie on the floor. TR
1940s house in St. Paul. The homeowner swapped this receptacle; the device is pulled out for inspection. The panel was replaced in 2019 with combination AFCI breakers (not GFCI or dual-function).

What's wrong here?

  1. A three-prong receptacle is on a circuit with no ground and no GFCI
  2. A replacement receptacle in a living room is missing AFCI protection
  3. The replacement receptacle is not a tamper-resistant type
  4. Nothing. This installation is compliant
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Show the answer and the code reference

The answer

A grounding-type (three-prong) receptacle was installed as a replacement on a two-wire circuit with no equipment grounding conductor, without GFCI protection or 'GFCI Protected' and 'No Equipment Ground' labeling.

Correct choice: 1. A three-prong receptacle is on a circuit with no ground and no GFCI

The cable has only two conductors and the old steel box is not grounded by any raceway or EGC, so the green screw has nothing to connect to. Where no grounding means exists in the box, 406.4(D)(2) allows only three choices: a non-grounding (two-prong) receptacle, a GFCI-type receptacle marked 'No Equipment Ground', or a grounding-type receptacle supplied through a GFCI and marked 'GFCI Protected' and 'No Equipment Ground'. A plain three-prong device with an open ground falsely tells the user that a surge strip, computer or tool with a grounding plug is grounded. The combination AFCI breaker meets the AFCI replacement rule but does not provide ground-fault protection for personnel.

How to fix it

Install a tamper-resistant GFCI receptacle here and mark it 'No Equipment Ground', or supply this device through a GFCI or dual-function breaker or an upstream GFCI and mark it 'GFCI Protected' and 'No Equipment Ground'; any three-prong devices downstream of a GFCI get both labels too. Alternatively, add an equipment grounding conductor as permitted by 250.130(C), or go back to a two-prong receptacle.

Code references

  • NEC 2023 406.4(D)(2) — Replacements: Non-Grounding-Type Receptacles

    Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, the replacement shall be (a) a non-grounding-type receptacle, (b) a GFCI-type receptacle, with it or its cover plate marked 'No Equipment Ground', or (c) a grounding-type receptacle supplied through a GFCI and marked 'GFCI Protected' and 'No Equipment Ground'. No equipment grounding conductor may be connected between these receptacles.

    Drills citing 406.4(D)(2)

  • NEC 2023 406.4(D)(4) — Replacements: Arc-Fault Circuit-Interrupter Protection

    Where a receptacle outlet in an area that requires AFCI protection under 210.12 is replaced, the replacement shall be a listed outlet branch-circuit AFCI receptacle, a receptacle protected by one, or a receptacle protected by a listed combination-type AFCI circuit breaker, subject to a narrow exception.

    Drills citing 406.4(D)(4)

  • NEC 2023 406.4(D)(5) — Replacements: Tamper-Resistant Receptacles

    Listed tamper-resistant receptacles shall be provided where replacements are made at receptacle outlets that are required to be tamper-resistant elsewhere in the Code, except where a non-grounding receptacle is replaced with another non-grounding receptacle.

    Drills citing 406.4(D)(5)

  • NEC 2023 250.130(C) — Nongrounding Receptacle Replacement or Branch Circuit Extensions

    The equipment grounding conductor of a grounding-type replacement receptacle or branch-circuit extension may be connected to specific points, such as any accessible point on the grounding electrode system or grounding electrode conductor, the equipment grounding terminal bar in the enclosure where the circuit originates, or an EGC of another branch circuit that originates in that same enclosure.

    Drills citing 250.130(C)

2026 NEC:not yet checked Confidence: low

Minnesota

MN adopts the NEC rule as writtenConfidence: medium

Minnesota adopted the 2023 NEC without amendment (Minn. Stat. 326B.35; Minn. Rules 1315.0200), so 406.4(D) applies as published to permits filed July 1, 2023 through Aug. 16, 2026. Permits filed on or after Aug. 17, 2026 fall under the 2026 NEC; see the 2026 NEC note on this drill. Separately, an owner-occupant may do electrical work on their own single-family home without a license (Minn. Stat. 326B.33), but the work is generally still permitted and inspected; St. Paul performs its own electrical inspections, so check with the city on whether a device swap needs a permit.

How Minnesota adopts the NEC

Why the other choices are wrong

  • A replacement receptacle in a living room is missing AFCI protection. 406.4(D)(4) does require AFCI protection for this replacement, but a combination AFCI breaker at the panel is one of the permitted means, and the caption says that is in place.
  • The replacement receptacle is not a tamper-resistant type. 406.4(D)(5) does require a tamper-resistant replacement here, but this device is marked TR.
  • Nothing. This installation is compliant. A three-prong receptacle with no ground path invites users to trust a ground that is not there; 406.4(D)(2) permits it only with GFCI protection and the 'No Equipment Ground' marking.
Safety hazardLevel 3 · Master#receptacle#replacement#ungrounded#gfci#old-house

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