Reading and executing a wiring a switched outlet diagram is one of the most common residential electrical tasks, yet it remains a frequent source of tripped breakers and dead lamps. A switched outlet—specifically the "half-hot" configuration where the top half is controlled by a wall switch and the bottom half remains constantly powered—requires a 3-wire cable run and a physical modification to the receptacle itself. The direct answer for a standard modern installation (power entering the switch box first) is to run 14/3 or 12/3 NM-B cable from the switch to the outlet. You must break the brass connecting tab on the hot side of the duplex receptacle, land the always-hot black wire on one brass screw, the switched-hot red wire on the other brass screw, the white neutral on the silver screw, and the bare ground on the green screw.

This guide assumes a "power-to-switch" topology, which is required by NEC 404.2(C) for new construction to ensure a neutral wire is present at the switch box for smart switches. If you are working on an older home with a "switch loop" (power to the outlet first, 2-wire to the switch), the color coding will differ, and you must re-identify the white wire as a hot conductor.

Tools, Materials, and Device Ratings

Before pulling any wire, you must match your cable gauge to your breaker size and receptacle rating. The National Electrical Code (NEC) dictates strict ampacity limits. Never install a 15A receptacle on a 20A circuit if it is the only outlet on that circuit, though NEC 210.21(B)(3) allows 15A receptacles on a 20A circuit if there are multiple outlets on the branch.

Materials List

  • Receptacle: 15A / 125V Duplex Receptacle (e.g., Leviton 5262) for a 15A circuit, or a 20A / 125V Duplex (e.g., Leviton 5266) for a dedicated 20A circuit.
  • Cable (Switch to Outlet): 14/3 NM-B (Romex) with ground for a 15A breaker, or 12/3 NM-B with ground for a 20A breaker. The third wire (red) is mandatory for the switched hot.
  • Cable (Panel to Switch): 14/2 NM-B or 12/2 NM-B, matching the circuit ampacity.
  • Wall Switch: Standard 15A single-pole toggle or smart switch (e.g., Lutron Caseta PD-5S-DV).
  • Wire Nuts: Yellow or red winged wire connectors rated for the specific wire combination (e.g., Ideal Wire-Nut 341).

Tool List

  • Wire Strippers: Klein Tools 1105-4E (for 14-10 AWG solid copper).
  • Multimeter: Fluke 117 or equivalent CAT III true-RMS meter with non-contact voltage (NCV) detection.
  • Screwdrivers: #2 Robertson (square) and #2 Phillips insulated drivers.
  • Needle-Nose Pliers: For forming precise J-hooks on solid copper wire.
⚠️ MAINS SAFETY CALLOUT: This procedure involves 120V AC mains voltage, which can cause fatal electrocution or arc flash.
  1. Turn off the circuit breaker at the main panel.
  2. Apply a lockout/tagout device if others are in the home.
  3. Verify the circuit is dead using a tested non-contact voltage tester and a multimeter. Measure from black to white, black to ground, and white to ground. All readings must be exactly 0.0V before touching any bare copper.

Step-by-Step: Executing the Wiring a Switched Outlet Diagram

The following steps detail the terminations for a power-to-switch configuration. Strip exactly 3/4 inch of insulation from all 14 AWG or 12 AWG solid copper wires to ensure full seating under the terminal screws without exposing bare copper outside the wire clamp.

  1. Prepare the Switch Box (Power In): Route the 14/2 NM-B from the panel and the 14/3 NM-B to the outlet into the switch box. Connect all bare ground wires together with a pigtail to the switch's green ground screw. Connect the white neutral from the 14/2 panel feed directly to the white neutral of the 14/3 outlet feed using a wire nut. (The switch itself does not terminate the neutral unless it is a smart switch requiring a neutral).
  2. Terminate the Switch Hot Terminals: Connect the black wire from the 14/2 panel feed to the bottom brass terminal of the single-pole switch. Connect the red wire from the 14/3 outlet feed to the top brass terminal of the switch. The red wire is now your "switched hot." Cap the black wire of the 14/3 cable with a wire nut; it will pass through this box to carry always-hot power to the outlet.
  3. Prepare the Receptacle: At the outlet box, strip the 14/3 NM-B sheathing. Identify the brass (hot) side and the silver (neutral) side of the duplex receptacle. Using your needle-nose pliers, grip the small brass connecting tab between the top and bottom brass screws. Bend it back and forth until it snaps off completely. Do not touch the silver tab on the neutral side.
  4. Land the Neutral and Ground: Form a J-hook on the bare ground wire and secure it clockwise under the green grounding screw on the receptacle. Form a J-hook on the white neutral wire and secure it clockwise under either of the silver terminal screws. Because the silver tab is intact, both the top and bottom halves of the outlet share this neutral return path.
  5. Land the Always-Hot Wire: Take the black wire from the 14/3 cable (the always-hot feed passed through the switch box). Form a J-hook and terminate it on the bottom brass screw of the receptacle. This ensures the bottom half of the outlet is constantly powered.
  6. Land the Switched-Hot Wire: Take the red wire from the 14/3 cable. Form a J-hook and terminate it on the top brass screw of the receptacle. Because you broke the brass tab in Step 3, this top half is now electrically isolated from the bottom half and will only receive power when the wall switch closes the circuit.
  7. Secure and Dress: Wrap a single layer of 3M Super 33+ electrical tape around the perimeter of the receptacle, covering the terminal screws. This prevents accidental shorts against the metal outlet box. Fold the wires in a Z-pattern (grounds first, then neutrals, then hots) and secure the device to the box with the provided 6-32 mounting screws.

Verify and Test: Meter Readings and the Vaporized Tab Botch

Never assume a wiring a switched outlet diagram was executed perfectly just because the wires are tight. You must verify the circuit behavior before plugging in expensive electronics or lamps.

Expected Meter Readings

Restore power at the breaker. Set your Fluke 117 to AC Voltage (V~).

  • Bottom Brass to Silver (Switch OFF): 120V (±5%). This confirms the always-hot black wire is functioning.
  • Top Brass to Silver (Switch OFF): 0V. This confirms the switch is open and the brass tab was successfully broken.
  • Top Brass to Silver (Switch ON): 120V (±5%). This confirms the red switched-hot is completing the circuit.
  • Ground to Silver: 0V. Confirms neutral and ground are not bonded at the receptacle (a severe code violation).

The Most Common Botch: The Vaporized Brass Tab

The most catastrophic mistake when wiring a switched outlet occurs in homes with a Multi-Wire Branch Circuit (MWBC). An MWBC uses a 3-wire cable where the black wire is on Phase A (120V) and the red wire is on Phase B (120V), sharing a single white neutral. There is 240V of potential difference between the black and red wires.

The Botch: The electrician lands the MWBC black wire on the top brass screw and the red wire on the bottom brass screw, but forgets to break the brass connecting tab.

The Symptom: When the breaker is turned on, 240V is dead-shorted directly across the thin brass connecting tab. The tab instantly vaporizes in a bright arc flash, destroying the receptacle and potentially causing severe burns. The Fix: Always verify if your 3-wire feed is a standard single-phase 120V switch loop (black and red on the same breaker) or a 240V MWBC (black and red on a double-pole breaker). If it is an MWBC, breaking the brass tab is not optional; it is a critical safety requirement to prevent a phase-to-phase dead short.

Frequently Asked Questions

Can I use a 15A outlet on a 20A circuit for a switched lamp?

Yes, but only if there is more than one receptacle on that 20A circuit. Under NEC 210.21(B)(3), a 15A duplex receptacle (like the Leviton 5262) is permitted on a 20A branch circuit because the assumption is that multiple outlets will distribute the load, preventing any single 15A device from being overloaded to 20A. However, if this switched outlet is the only receptacle on the entire 20A circuit (a dedicated run), you must install a 20A rated receptacle (Leviton 5266) which features the T-shaped neutral slot. Always match your wire gauge to the breaker: 12 AWG NM-B for a 20A breaker.

Do I need to break the tab on both the brass and silver sides?

No. For a standard half-hot switched outlet, you only break the brass (hot) tab. The silver (neutral) tab must remain intact so that both the top and bottom halves of the outlet share the same white neutral return path. If you accidentally break the silver tab, the half of the outlet that does not have the white wire landed on its silver screw will have no neutral return path, rendering it completely dead. Furthermore, if you land two separate white wires on a broken silver tab in an MWBC setup, you can create a dangerous neutral overload condition.

Why does my switched outlet trip the GFCI breaker when I flip the switch?

If flipping the switch immediately trips a GFCI breaker or receptacle, you have likely created a neutral-to-ground fault or a crossed neutral scenario. This frequently happens when the switched hot (red wire) is returning through a neutral path that bypasses the GFCI's sensing coil, or if the white neutral wire from the switch box is mistakenly landed on the ground bus instead of the neutral bus. Another common cause is "neutral mixing," where the neutral for the switched outlet is accidentally wire-nutted to neutrals from a different, non-GFCI circuit in the switch box. The GFCI detects this imbalance (current leaving on the hot but returning on a foreign neutral) and trips to prevent electrocution. Isolate the outlet's white neutral so it pairs exclusively with its own black and red hots.