Missouri Electrical Code: GFCI Requirements for Kitchens and Bathrooms

A ground-fault circuit interrupter watches the current on the hot wire and compares it to the current coming back on the neutral. If more than 4–6 milliamps "leaks" to ground — through a person, a wet wire, anything — it trips in about 1/40th of a second. That is fast enough to prevent a lethal shock. It does not protect against overloads (that is the breaker) or arcs (that is an AFCI). GFCI is a shock-protection device, nothing more, nothing less.

Any 125V–250V receptacle on a 15A or 20A circuit in a dwelling bathroom needs GFCI protection. Not "within 6 feet of the sink" — anywhere in the bathroom. The required dedicated 20A bathroom circuit (210.11(C)(3)) can serve all bathrooms in the house, but every receptacle on it has to be GFCI-protected. The cheap way: one GFCI receptacle at the first box, "LINE" terminals wired to the panel, "LOAD" terminals feeding the other outlets downstream — they inherit the protection.

Pre-2020, only receptacles "serving the countertop surfaces" needed GFCI protection in a kitchen. The 2020 NEC changed the trigger from "countertop" to "receptacles installed in the kitchen" — meaning the fridge receptacle, the microwave outlet, the garbage disposal, and under-cabinet lights all now need GFCI. If you are permitting under 2020 NEC (most of Missouri outside KC single-family), plan for GFCI protection on every kitchen 125V receptacle, not just the two on the counter.

The full 2020 NEC 210.8(A) list for dwellings: bathrooms, garages, outdoor receptacles, crawlspaces at or below grade, unfinished basements, kitchens, sinks (within 6 feet), bathtubs/showers (within 6 feet), laundry areas, and indoor damp/wet locations. If you are rewiring a basement laundry room, you need GFCI on the washer, the utility sink, and anything else down there. One $20 GFCI receptacle at the start of the run protects everything downstream.

A GFCI receptacle has two sets of terminals: LINE (power coming from the panel) and LOAD (power going downstream to other outlets). Wire the incoming hot/neutral from the panel to LINE. Wire the outgoing hot/neutral to LOAD only if you want downstream outlets protected by this GFCI. Reversing LINE and LOAD is the most common install error — the outlet works but the test button does not trip downstream outlets, and the inspector catches it in 3 seconds. The receptacle has arrows and labels — follow them.

NEC and GFCI manufacturers both say to test monthly. Push TEST — the RESET button should pop out and power to the outlet (and any downstream outlets) should die. Push RESET — power comes back. If TEST does not kill power, the GFCI function has failed and the receptacle needs to be replaced. Self-test GFCIs (anything made after 2015) do this automatically and will refuse to reset if the function is bad, which is a real safety improvement.

The 2020 NEC kitchen expansion matters more if you are in a jurisdiction on the 2020 or 2023 cycle. Kansas City uses the 2017 NEC for one- and two-family dwellings — the pre-expansion rules still apply there. St. Louis County jumped to the 2023 NEC in January 2025, which further expanded GFCI to additional locations. Call your building department and ask which NEC cycle they inspect under before you buy materials.