Wiring a 6-30R Receptacle: 240V 30A Breaker & 10 AWG Guide

A NEMA 6-30R is a 240-volt, 30-amp, 3-wire receptacle. It provides two hot legs and a ground, but no neutral. You will find this configuration powering 240V-only loads like MIG welders, large air compressors, pottery kilns, and older electric vehicle supply equipment (EVSE). Because it lacks a neutral, it cannot supply 120V to any device requiring a 120/240V split (like a modern dryer with a 120V timer motor).

The direct answer: To wire a 6-30R receptacle, you need a 30A 2-pole breaker and 10 AWG copper wire. The black and red (or re-identified white) hot wires land on the two brass X and Y terminals, and the bare/green ground wire lands on the green G terminal. There is no neutral terminal on this device.

The Decision Path: Wire, Conduit, and Device Selection

Before pulling wire, you must match your cable type to your installation environment and verify your load actually accepts a 6-30P plug. Use this decision matrix to lock in your materials.

Tools, Materials, and Mains Safety

Working on a 240V circuit involves both poles of your split-phase residential service. A shock across these two hot legs delivers 240V directly through the chest cavity, which is highly lethal.

Required Tools & Materials

• Breaker: 30A 2-pole (e.g., Square D HOM230 or QO230, matched to your panel brand).
• Wire: 10 AWG copper (THHN in conduit OR 10/2 NM-B).
• Receptacle: NEMA 6-30R (Leviton 278-S00 or Hubbell 2620).
• Box: 4x4x2-1/8'' metal junction box (minimum 15 cubic inches required by NEC 314.16 for three 10 AWG wires plus the device yoke).
• Strippers: Klein 11055 or equivalent for 10 AWG.
• Torque Screwdriver: Calibrated to inch-pounds (e.g., Klein 69010).
• Multimeter: True-RMS CAT III/IV (e.g., Fluke 117).
• Tape: Black or red electrical tape (only if using 10/2 NM-B).

Step-by-Step: Wiring the 6-30R Receptacle

Follow these termination steps exactly. The NEMA 6-30R has three terminals: X (Hot 1), Y (Hot 2), and G (Ground). Because this is a pure 240V load, X and Y are electrically interchangeable; polarity between the two hot legs does not matter for the operation of the equipment.

1. Prepare the Box and Cable: If using 10/2 NM-B, strip the outer yellow sheathing back to within 1/4'' of the cable clamp inside the box. Leave at least 6'' of wire length past the box edge. If using THHN, ensure the wires are pulled through and cut to length.
2. Re-identify the White Wire (NM-B Only): If you are using 10/2 NM-B, the white wire must serve as your second hot leg. Per NEC 200.7(C)(1), you must permanently re-identify this white wire at both the panel and the receptacle end using black or red electrical tape, or a permanent marker. Wrap the tape completely around the insulation.
3. Strip the Conductors: Strip exactly 3/4'' of insulation from the black, red (or taped white), and bare/green wires. Do not nick the copper; nicks create hot spots under high continuous loads like welding.
4. Land the Ground (Green/Bare): Connect the bare copper or green THHN wire to the Green Ground Screw (G) on the receptacle. If using a metal box, you must also run a 10 AWG green grounding pigtail from the box's grounding screw to the receptacle's ground terminal, or use a self-grounding receptacle strap (though a pigtail is preferred for 30A shop loads).
5. Land Hot 1 (Black): Insert the stripped black wire into the terminal block marked X. Tighten the screw.
6. Land Hot 2 (Red or Taped White): Insert the red (or re-identified white) wire into the terminal block marked Y. Tighten the screw.
7. Torque to Specification: Using your torque screwdriver, tighten the X, Y, and G terminal screws to 14 in-lbs (verify with your specific manufacturer's insert; Leviton typically specifies 14-18 in-lbs for 10 AWG). Proper torque prevents terminal arcing and melting under sustained 25A+ continuous draws.
8. Mount and Cover: Push the wires neatly into the back of the 4x4 box, fold them in an accordion pattern rather than forcing them. Mount the receptacle to the box using the provided 6-32 machine screws, and install a 6-30R specific weatherproof or flat cover plate.

The Most Common Botch: 6-30R vs 14-30R and Re-Identification

The most frequent failure mode on a 240V 30A circuit is installing the wrong receptacle for the appliance, or failing to re-identify the neutral in a 2-wire cable.

Botch 1: The 'White Wire' Trap

The Error: A DIYer runs 10/2 NM-B to a 6-30R but forgets to wrap the white wire in black tape. They land it on the Y terminal.
The Symptom: The circuit works perfectly. However, when the house is sold or an electrician troubleshoots the panel later, they see a white wire on a 2-pole breaker and assume it is a shared neutral (Multi-Wire Branch Circuit). This can lead to catastrophic miswiring at the panel, or an inspector will fail the rough-in immediately.
The Fix: Always apply black or red tape at both the breaker and the receptacle. Better yet, just pull 10 AWG THHN in conduit so you have a dedicated red wire.

Botch 2: Confusing 6-30R with 14-30R

The Error: Attempting to wire a modern 4-prong dryer (NEMA 14-30P) or a 120V/240V EV charger to a 6-30R receptacle by 'adapting' the neutral to ground.
The Symptom: The 120V components (timers, control boards, Wi-Fi modules in EVSEs) will fry, or the GFCI protection on the appliance will trip instantly because neutral current is flowing on the equipment grounding conductor.
The Fix: A 6-30R has no neutral bus. If your appliance has a 4-prong plug requiring 120V, you must change the receptacle to a NEMA 14-30R and run 10/3 NM-B (or 4 wires in conduit) to provide a dedicated, insulated neutral.

Verify and Test: Expected Multimeter Readings

Never plug in a 30A load without verifying the voltage at the receptacle blades first. A miswired ground can energize the chassis of a welder or compressor.

Set your multimeter to AC Voltage (V~). Insert the probes into the slots of the 6-30R face (or test the exposed terminals before installing the cover plate).

By strictly adhering to 10 AWG sizing, proper re-identification, and calibrated torque, your 6-30R installation will safely handle continuous 24A loads (the NEC 80% continuous load limit for a 30A breaker) without thermal degradation. Always defer to your local Authority Having Jurisdiction (AHJ) for final inspection and code compliance.