To wire a combination switch and outlet for a switched light and an always-hot receptacle on a standard 15A residential circuit, use 14 AWG copper wire. Terminate the incoming black (hot) wire to the brass LINE screw, the outgoing black (load) wire to the brass LOAD screw, the white (neutral) wire to the silver screw, and the bare copper (ground) wire to the green ground screw. You must also break the brass connecting fin on the side of the device to isolate the switch from the outlet.

The Decision Path: Choose Your Combo Device Configuration

Combination devices (a single-gang unit housing one toggle switch and one duplex receptacle) are wired differently depending on what the switch is actually controlling. Before you strip a single wire, you must define your circuit topology. The most common point of failure in these installations is buying the wrong device or failing to modify the internal metal fins (tabs) that link the switch and outlet terminals.

Application ScenarioInternal Fin ModificationWire Gauge & BreakerConcrete Device Pick
Scenario A: Switch controls a separate ceiling light; outlet remains always-hot.Break the Brass (hot-side) fin. Leave Silver fin intact.14 AWG on 15A breakerLeviton 5243-W (15A/120V)
Scenario B: Switch controls a separate ceiling light; outlet remains always-hot.Break the Brass (hot-side) fin. Leave Silver fin intact.12 AWG on 20A breakerLeviton 5245-W (20A/120V)
Scenario C: Switch controls the top half of the outlet; bottom half is always-hot.Break Both Brass and Silver fins. (Requires 2 hot feeds).14 AWG on 15A breakerLeviton 5243-W (Modified)
The Default Pick: For 90% of residential retrofits and new additions (Scenario A on a 15A lighting/receptacle branch circuit), your concrete pick is the Leviton 5243-W. It is a 15A, 120V combination device with side-wire screw terminals. Avoid devices with push-in (backstab) terminals for combo units, as the internal spring contacts are prone to thermal failure under continuous load.

Tools, Materials, and Device Ratings

A combination device counts as two devices for NEC box fill calculations (per NFPA 70 / NEC Article 314.16). If you are stuffing two 14 AWG cables (incoming and outgoing) plus a combo device into a standard 18 cubic-inch single-gang box, you will exceed the box fill limit. Use a deep single-gang box (minimum 22.5 cubic inches) to prevent wire crushing and overheating.

  • Device: Leviton 5243-W (15A Combo Switch/Receptacle)
  • Wire: 14 AWG NM-B (Romex) for 15A circuits; 12 AWG for 20A circuits. (Copper only; do not use aluminum for 15A/20A branch circuits).
  • Strippers: Klein Tools 11063W (strips exactly 5/8" for standard terminal hooks).
  • Testers: Klein NCVT-2 (Non-Contact Voltage Tester) and a Fluke 117 True-RMS Multimeter.
  • Connectors: Ideal 341 Orange wire nuts (for 14 AWG pigtailing).
  • Screwdriver: #2 Phillips and 1/8" flathead (for fin breaking).

Mains Safety Protocol: De-Energize and Verify

CRITICAL SAFETY WARNING: This procedure involves 120V AC mains voltage, which is lethal. You must de-energize the circuit, lock or tape the breaker in the OFF position, and verify the absence of voltage before touching any conductor. Never rely solely on a wall switch being in the "off" position. Always follow OSHA Lockout/Tagout principles adapted for residential work.
  1. Locate and Trip: Identify the correct breaker in your main panel and switch it to the OFF position. Place a piece of electrical tape over the breaker handle to prevent accidental re-energization.
  2. Initial Sweep: Insert your Klein NCVT-2 into the slots of the existing outlet. The tester should remain dark/silent. If it beeps, you have the wrong breaker. Stop and re-evaluate.
  3. Multimeter Verification: Set your Fluke 117 to AC Volts (V~). Insert the probes into the top receptacle slots (Line to Neutral). The reading must be 0.0V. Repeat for Line to Ground (the round hole). Reading must be 0.0V.
  4. Expose Conductors: Unscrew the existing device, pull it out gently, and test the exposed bare copper ground and black wires directly with the multimeter probes to confirm absolute zero potential.

Step-by-Step: Wiring the Combination Switch and Outlet

The following steps assume Scenario A: The switch controls a downstream light fixture, and the outlet remains always-hot. You have one incoming 14/2 cable (power from panel) and one outgoing 14/2 cable (load to light).

  1. Prep the Conductors: Strip exactly 5/8 inch of insulation from the black, white, and bare copper wires on both the incoming and outgoing cables. Do not nick the copper; nicks create hot spots.
  2. Break the Brass Fin: Look at the side of the Leviton 5243-W with the brass screws. You will see a small metal tab connecting the two brass screws. Use your 1/8" flathead screwdriver or needle-nose pliers to bend this tab back and forth until it snaps off. Leave the silver-side fin intact.
  3. Terminate Ground (Bare Copper): Twist the incoming bare copper wire and the outgoing bare copper wire together with a 6-inch 14 AWG bare copper pigtail. Cap with an orange wire nut. Hook the pigtail clockwise around the Green Ground Screw on the device and tighten until the screw head is flush.
  4. Terminate Neutral (White): Twist the incoming white wire, the outgoing white wire, and a 6-inch 14 AWG white pigtail together. Cap with a wire nut. Hook the white pigtail clockwise around the Silver Neutral Screw on the device. (The switch does not use the neutral; it only feeds the receptacle half).
  5. Terminate Incoming Hot (Black Line): Take the incoming black wire (power from the breaker panel). Hook it clockwise around the brass screw marked LINE (or the brass screw closest to the silver screw, depending on the specific revision). Tighten firmly.
  6. Terminate Switched Load (Black Load): Take the outgoing black wire (running to the ceiling light). Hook it clockwise around the brass screw marked LOAD (the isolated brass screw). Tighten firmly.
  7. Final Torque and Dressing: Ensure no bare copper is visible outside the screw heads, and no insulation is caught under the screw washers. Fold the wires into the back of the deep box: grounds first, then neutrals, then hots. Mount the device and tighten the mounting screws evenly to prevent yoking distortion.

Verify and Test: Expected Meter Readings

Before plugging in any loads or installing the faceplate, restore power at the breaker and verify the circuit behavior with your multimeter.

  • Receptacle Test: Set multimeter to V~. Measure across the top outlet slots (Hot to Neutral). Expected reading: 118V - 122V. Measure the bottom outlet slots. Expected reading: 118V - 122V. The outlet is always hot.
  • Switch Load Test (OFF): Turn the toggle switch OFF. Measure the outgoing black load wire (at the wire nut in the ceiling box, or by testing the light fixture socket contacts if accessible) to ground. Expected reading: 0.0V.
  • Switch Load Test (ON): Turn the toggle switch ON. Measure the outgoing black load wire to ground. Expected reading: 118V - 122V. The light should illuminate.

The Most Common Botch: The Unbroken Fin and the Dead Outlet

The single most frequent mistake DIYers make when wiring a combination switch and outlet is failing to break the brass connecting fin.

The Symptom: You finish the installation, turn the breaker on, and plug a lamp into the outlet. The lamp does not turn on. You flip the wall switch to turn on the ceiling light, and suddenly, the lamp plugged into the outlet turns on as well. When you turn the ceiling light off, the outlet loses power.

The Physics: If the brass fin is left intact, the incoming hot wire (Line) feeds both the switch mechanism and the outlet's hot bus bar simultaneously. However, the switch mechanism acts as a gatekeeper for the entire brass side of the device. When the switch opens, it cuts the hot feed to the outlet entirely.

The Fix: De-energize the circuit, pull the device out, and snap off the brass fin. This physically separates the switch's load terminal from the outlet's hot bus, allowing the incoming Line wire to feed the outlet continuously while the switch independently gates the outgoing Load wire to the light fixture.

By following this exact terminal mapping, respecting NEC box fill limits, and verifying your zero-potential state before touching a single conductor, your combination device will operate safely and reliably for decades.