The Verdict: Are Standard Wall Outlets AC or DC?

Every standard residential wall outlet in North America is 120V AC (Alternating Current). The power delivered by your utility and distributed through your home's branch circuits is AC because it is vastly more efficient to transmit over long distances and step down via transformers. DC (Direct Current) is only found in specific, isolated home applications: the internal circuitry of your electronics, dedicated off-grid solar battery banks, or the low-voltage USB ports built into modern combo receptacles.

If you are asking "is my outlet AC or DC?" because you want to charge modern devices directly from the wall without bulky power bricks, you do not need to rewire your house for DC. Instead, you need a 120V AC receptacle with an integrated USB-C Power Delivery (PD) DC step-down converter. These devices take the 120V AC from your branch circuit, pass it through to the standard AC plugs, and route a parallel feed into an internal switching power supply that outputs regulated 5V to 20V DC to the USB-C terminals.

The Decision Path: Which Receptacle Do You Actually Need?

Do not guess. Use this decision matrix to select the exact device rating and form factor for your load. For modern residential upgrades where you want both standard appliance power and high-speed device charging, the concrete pick is the Leviton T5636 (15A, 125V AC, 30W USB-C PD).

Load Type & Goal Voltage Required Concrete Device Pick Device Rating
Standard Appliances (TV, Lamp, Vacuum) 120V AC Only Leviton 5262-SW (Standard Duplex) 15A, 125V
Laptops, Phones, Tablets + Standard Plugs 120V AC + 5V-20V DC Leviton T5636 (USB-C PD Combo) 15A AC, 30W DC
Off-Grid / RV / Solar 12V Systems 12V DC Only Blue Sea Systems 9005 (12V Socket) 15A DC, 12V

Tools, Materials, and Device Ratings

For this installation, we are wiring the Leviton T5636 USB-C PD combo outlet on a standard 15-amp residential branch circuit. Using the correct wire gauge and torque is non-negotiable to prevent thermal failure at the terminals.

Material Checklist:
  • Wire: 14 AWG NM-B (Romex) for a 15A breaker. (If your breaker is 20A, you must use 12 AWG NM-B and a 20A-rated receptacle like the Leviton T5637).
  • Device: Leviton T5636-W (15A, 125V AC, 30W USB-C PD, White).
  • Wall Plate: Leviton 88000 (Mid-size 1-gang plate, required because the USB-C body is deeper and wider than a standard duplex).

Tool Checklist:

  • Klein 11055 Wire Stripper (for clean 14 AWG stripping without nicking the copper).
  • Milwaukee 2202-20 Non-Contact Voltage Tester (NCVT).
  • Fluke 117 True-RMS Digital Multimeter.
  • Klein 70902 Torque Screwdriver (set to 14 in-lbs, per Leviton's terminal spec).
  • USB-C Voltmeter/Ammeter dongle (for final DC verification).

Mains Safety: De-Energize and Verify

CRITICAL SHOCK HAZARD: You are working with 120V AC mains voltage, which is lethal. Never work on a live circuit.
  1. Go to your main electrical panel and switch OFF the 15A or 20A breaker controlling the outlet.
  2. Apply a breaker lockout/tagout device if you are not the only person in the home.
  3. Insert your NCVT into the top and bottom slots of the existing outlet. The tester must remain completely dark and silent.
  4. Remove the faceplate and unscrew the old receptacle. Test the bare ground wire against the black hot wire with your multimeter to confirm 0.0V AC before touching any terminal screws.

Note: NEC-style guidance requires proper de-energization; your local AHJ may require a licensed electrician for panel work or new circuit runs.

Step-by-Step: Wiring the Leviton T5636 AC/DC Combo Outlet

The internal switching power supply that generates the DC output for the USB-C ports requires a correct Line/Load orientation to function. If you wire the hot and neutral backward, the AC outlets will work, but the DC USB ports will output zero volts due to an internal safety interlock.

  1. Prep the Box and Wires: Pull the 14 AWG NM-B cable into the box. Strip exactly 5/8-inch of the outer jacket. Strip exactly 1/2-inch of insulation from the black, white, and bare ground wires. Do not strip too much; exposed bare copper past the terminal yoke is a shock hazard.
  2. Terminate the Ground: Form a tight J-hook in the bare copper ground wire. Hook it clockwise around the Green grounding screw on the bottom of the Leviton T5636. Tighten to 14 in-lbs.
  3. Identify Line vs. Load: Look at the back of the receptacle. You will see two sets of Brass (Hot) and Silver (Neutral) screws. The top set is typically LINE (power coming from the panel), and the bottom is LOAD (power passing to the next outlet). If this is the last outlet on the run, you only use the LINE screws.
  4. Terminate the Neutral: Form a J-hook in the White neutral wire. Hook it clockwise around the Silver LINE screw. Tighten to 14 in-lbs. Ensure no white insulation is clamped under the screw head, and no bare copper is visible outside the terminal pad.
  5. Terminate the Hot: Form a J-hook in the Black hot wire. Hook it clockwise around the Brass LINE screw. Tighten to 14 in-lbs.
    Pro-Tip: The Leviton USB-C outlets use a combination screw/head design. You can use the side wire entry holes for straight-wire insertion, but the J-hook method under the screw head provides a more reliable mechanical grip for 14 AWG solid copper.
  6. Fold and Mount: Carefully fold the wires into the back of the box. The T5636 has a deep body (approx. 1.4 inches) because of the internal DC transformer. Push the transformer module in first, then fold the ground wire flat against the back, followed by the neutral and hot. Secure the device to the box with the provided 6-32 mounting screws. Snap on the mid-size faceplate.

Verify and Test: Expected Meter Readings

Do not plug in expensive electronics until you have mathematically verified the wiring. Go to the panel and flip the breaker back ON.

1. AC Verification (Fluke 117 Multimeter):

  • Hot (Short Slot) to Neutral (Long Slot): Expected reading is 114V to 126V AC. (Nominal is 120V).
  • Hot to Ground (U-Shape Slot): Expected reading is 114V to 126V AC.
  • Neutral to Ground: Expected reading is less than 2.0V AC. If this reads 120V, you have an open neutral or a swapped hot/neutral. Turn the breaker off immediately and re-check your silver and brass terminations.

2. DC Verification (USB-C Tester):

  • Plug a USB-C voltmeter dongle into the top port. The baseline reading should immediately show 5.0V to 5.2V DC.
  • Plug in a modern laptop or phone that supports USB-C Power Delivery negotiation. The tester should show the voltage stepping up to 9V, 15V, or 20V DC as the device's internal IC negotiates with the Leviton's PD controller via the CC (Configuration Channel) pin.

The Most Common Botch and How to Avoid It

The Botch: Reversing the Line and Load hot/neutral wires, or swapping Hot and Neutral entirely (putting Black on Silver and White on Brass).

The Symptom: You plug a lamp into the AC slots, and it turns on perfectly. You plug your phone into the USB-C slot, and it registers 0.0V DC. The user assumes the outlet is defective and returns it.

The Physics & The Fix: According to NEC receptacle wiring standards and UL listing requirements for smart/USB outlets, the internal DC power supply is wired in parallel with the LINE side terminals. Furthermore, the internal switching power supply has a safety interlock that monitors the polarity of the AC feed. If the hot and neutral are reversed, or if the power is fed into the LOAD terminals while the LINE terminals are empty, the interlock opens the DC relay to prevent backfeeding or shock hazards.

To fix it: De-energize the circuit, pull the outlet out, and verify that the Black wire from the panel is on the Brass LINE screw, and the White wire from the panel is on the Silver LINE screw. If you are feeding power downstream to another outlet, ensure your downstream wires are on the LOAD screws. Once corrected, the DC ports will energize immediately.