Kitchen Island and Small-Appliance Circuit Allocation
A 1978 split-level house is being remodeled. The 150 A panel has two existing 20 A small-appliance circuits serving the kitchen countertop receptacles. The owner wants to add a 12 in × 36 in island with two receptacles, a 120 V built-in microwave hood rated 14 A, a 120 V dishwasher rated 11 A, a 1/2 hp disposal, and under-cabinet LED lights. To save money, the owner asks whether the island receptacles, microwave, and dishwasher can all be fed from the existing 20 A circuit closest to the panel. The walls are open, and the existing countertop receptacles are not GFCI protected. The island has a 4 in × 4 in × 1 1/4 in metal box marked 18.0 cu in, currently containing one 12/2 NM cable and a GFCI receptacle, with cable clamps. The contractor plans to add a second 12/2 NM cable to feed a downstream island receptacle.
1. Can the island receptacles, microwave hood, and dishwasher share one existing 20 A small-appliance circuit? Explain the circuit allocation and load reasoning.
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No. The two 20 A small-appliance circuits are for countertop and similar receptacle outlets, not fixed appliances. The microwave hood (14 A) and dishwasher (11 A) are fixed appliances and need their own branch circuits; putting both on one 20 A circuit also creates a 25 A connected load before the disposal or lights. The island receptacles can be supplied from a small-appliance circuit because they serve the kitchen countertop, but the circuit must be GFCI protected and must not feed the microwave, dishwasher, disposal, or under-cabinet lights. A practical plan: leave the two existing SA circuits for countertop/island receptacles, add a 20 A dedicated microwave circuit, a 20 A dishwasher circuit, a 20 A disposal circuit (or a 15 A circuit if the disposal nameplate allows), and a separate lighting circuit. Verify the panel load calculation before adding circuits.
2. What GFCI/AFCI protection and receptacle placement rules apply to the countertop and island?
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All 125 V, 15/20 A kitchen countertop receptacles, including the island, need GFCI protection. Under the edition Georgia has adopted, confirm whether an island receptacle is required; if the 2020-style rule applies, a 12 in × 36 in island needs at least one receptacle, and it must be located no more than 12 in below the countertop. Use tamper-resistant receptacles. AFCI protection is required for the kitchen branch circuits in a dwelling, so use AFCI breakers or a listed AFCI/GFCI combination device as the adopted code allows. The under-cabinet lights are not allowed on the small-appliance circuits; feed them from a lighting circuit. The dishwasher receptacle also needs GFCI protection because it is in the kitchen. Do not rely on the old non-GFCI receptacles; replace or protect them.
3. The island box is 4 × 4 × 1 1/4 in, marked 18.0 cu in, with one 12/2 NM cable, a GFCI receptacle, and cable clamps. Is it adequate for adding a second 12/2 NM cable for a downstream receptacle? Show box-fill reasoning.
Read the worked answer
The box is at its limit, not adequate with spare capacity. For 12 AWG, each conductor is 2.25 cu in. Existing: two circuit conductors + one equipment ground counted as one = 3 × 2.25 = 6.75; one GFCI yoke = 2 × 2.25 = 4.50; cable clamps = 2.25; total 13.50 cu in. Adding a second 12/2 NM cable adds two circuit conductors = 4.50, but the additional ground does not add because all grounds count as one. New total = 18.00 cu in. The box is marked 18.0 cu in, so it fits exactly, with no allowance for a plaster ring, a second device, or larger conductors. Because there is no margin, use a larger box or a 2-gang box. If any additional conductor or device is added, the box is violations.