How to Wire a Combo Switch Outlet: 15A Leviton 5243 Guide

A combo switch outlet packs a single-pole toggle switch and a standard duplex receptacle into a single-gang footprint. It is the standard fix for adding a switched overhead light to a hallway, basement, or bathroom where wall space only permits one gang box. For a standard 15-amp lighting and receptacle branch circuit, you will use 14 AWG copper wire and a 15A-rated combo device like the Leviton 5243-W or Eaton E5243.

This guide details the most common and useful configuration: the switch controls a separate overhead light fixture, while the receptacle remains always-hot. We assume a standard 120V nominal residential circuit with one 14/2 NM-B cable feeding line power into the box, and a second 14/2 NM-B cable exiting the box to feed the light.

Device Sizing and Circuit Specifications

Before stripping any wire, you must match the device rating to your branch circuit breaker and wire gauge. The National Electrical Code (NEC) strictly governs these pairings to prevent thermal overloads. While 15A duplex receptacles are permitted on 20A circuits under NEC 210.21(B)(3), matching a 15A combo device to a 15A breaker and 14 AWG wire is the cleanest, most code-compliant path for DIY retrofits.

Note: Even if your 14 AWG wire has 75°C or 90°C insulation (like THHN), NEC 240.4(D) strictly limits the overcurrent protection for 14 AWG copper to 15A. Always size your breaker to the smallest wire in the circuit run.

Tools, Materials, and Mains Safety Protocol

Required Tools

• Non-Contact Voltage Tester (NCVT): Klein NCVT-3 or equivalent for initial dead-check.
• Digital Multimeter: Fluke 117 or Klein MM400 (must measure AC Voltage and Continuity).
• Wire Strippers: Klein 11055 (calibrated for 14 AWG and 12 AWG solid copper).
• Torque Screwdriver: Wiha or Klein, set to 14 in-lbs (Leviton's spec for 14 AWG terminations).
• Phillips #2 Screwdriver: For mounting straps and plate covers.

Required Materials

• Combo Device: Leviton 5243-W (15A, 120V, single-pole switch + duplex receptacle).
• Wire: 14/2 NM-B (Romex) for feed and load, plus 14 AWG solid copper pigtails (black, white, green).
• Connectors: Yellow wire nuts (Ideal 302 or equivalent) for 14 AWG pigtailing.

Step-by-Step Wiring Procedure

Follow these steps to wire the combo device so the receptacle is always-hot and the switch controls the downstream light fixture.

1. De-Energize and Verify Dead

1. Turn off the 15A breaker controlling the circuit at the main panel.
2. Test your NCVT on a known live circuit to verify the tester's battery is functional.
3. Remove the existing wall plate and device screws. Pull the device out of the box.
4. Hold the NCVT near all wires in the box. It should remain silent/unlit.
5. Set your multimeter to AC Voltage (V~). Place the black probe on the bare ground wire and the red probe on the black hot wire. The reading must be 0.0V.

2. Prepare Pigtails and Conductors

1. Identify your Line In cable (power from the panel) and your Load Out cable (power going to the light). If unsure, cap all wires, turn the breaker on briefly, and test with the NCVT. The cable that triggers the NCVT is the Line In. Turn the breaker back off immediately after testing.
2. Strip exactly 3/4 inch of insulation from the ends of all black, white, and bare copper wires using the 14 AWG hole on your strippers.
3. Cut three 6-inch pigtails from your spare 14 AWG solid wire: one black, one white, and one green.

3. Terminate the Ground (Green/Bare)

1. Twist the bare copper ground wire from the Line In cable, the bare copper ground wire from the Load Out cable, and your green 14 AWG pigtail together.
2. Secure with a yellow wire nut.
3. Form a tight J-hook on the end of the green pigtail. Hook it clockwise around the green grounding screw on the combo device and torque to 14 in-lbs.

4. Terminate the Neutrals (White)

1. Twist the white neutral wire from the Line In cable, the white neutral wire from the Load Out cable, and your white 14 AWG pigtail together.
2. Secure with a yellow wire nut. (The switch mechanism does not require a neutral; this bundle completes the circuit for the receptacle and provides the return path for the light).
3. Form a J-hook on the white pigtail and hook it clockwise around the silver terminal screw on the receptacle side of the combo device. Torque to 14 in-lbs.

5. Terminate the Line Hot (Black)

1. Take the black wire from the Line In cable (incoming power).
2. Form a J-hook and connect it to the brass screw marked "LINE" (or the brass screw closest to the receptacle side if unmarked). This screw internally feeds both the always-hot receptacle and the switch input.
3. Critical Check: Ensure the small brass break-off fin between the two brass screws is intact. Do not snap it off with your lineman's pliers.

6. Terminate the Switched Load (Black)

1. Take the black wire from the Load Out cable (exiting to the light fixture).
2. Form a J-hook and connect it to the remaining brass screw marked "LOAD" (located on the switch side of the device).
3. Torque both brass screws to 14 in-lbs. Gently tug each wire to ensure a solid mechanical bite.

Verify and Test Sequence

Do not push the device back into the box until you have verified the terminations with live voltage. Neatly fold the wires into the back of the box (grounds first, then neutrals, then hots) and temporarily mount the device with the panel screws.

1. Turn the 15A breaker back ON at the main panel.
2. Set your multimeter to AC Voltage (V~).
3. Test 1 (Receptacle Hot-to-Neutral): Insert the red probe into the shorter (hot) slot of the top receptacle and the black probe into the longer (neutral) slot. Expected reading: 114V to 126V.
4. Test 2 (Receptacle Hot-to-Ground): Insert the red probe into the hot slot and the black probe into the U-shaped ground hole. Expected reading: 114V to 126V. (This verifies your equipment grounding path is intact).
5. Test 3 (Switch Operation): Leave the multimeter probes in the receptacle slots to confirm the outlet remains live regardless of the switch position. Then, plug a lamp or receptacle tester into the outlet. Toggle the switch; the receptacle power must not drop.
6. Test 4 (Light Fixture): Toggle the switch to the ON position. Verify the overhead light illuminates. Toggle OFF and verify it extinguishes.

Once all readings match expected values, turn the breaker off one last time to securely seat the device into the box, tighten the mounting straps, and install the wall plate.

The Most Common Botch: The Switched Receptacle Mistake

The most frequent error when wiring a combo switch outlet is accidentally creating a switched receptacle when an always-hot outlet was intended.

Why This Happens

Combo devices like the Leviton 5243 feature a small brass break-off fin connecting the two brass hot screws. This fin is designed to be snapped off only if you are wiring a "half-hot" receptacle (where the top outlet is switched and the bottom is always-hot, requiring two separate hot feeds).

If a DIYer mistakenly snaps off this fin, or lands the Line In hot wire on the "LOAD" brass screw while leaving the "LINE" brass screw empty, the internal jumper is broken. The receptacle is starved of line voltage and only receives power when the switch closes the circuit to the load terminal.

How to Fix It

1. De-energize the circuit and verify dead with your multimeter.
2. Inspect the hot side of the device. If the brass fin is missing, the device is permanently altered. You cannot solder it back together safely for a 15A load; you must replace the combo device.
3. If the fin is intact but the outlet is still switched, check your wire mapping. Ensure the incoming line black wire is on the LINE brass screw, and the outgoing light black wire is on the LOAD brass screw.

For more detailed code references regarding receptacle ratings and branch circuit sizing, consult the NFPA National Electrical Code free access portal. For exact dimensional and torque specifications, always refer to the Leviton 5243-W specification sheet prior to installation.