4-Wire Dryer Plug Wiring Diagram (NEMA 14-30)
This is a free printable 4 wire dryer plug diagram: download the diagram as SVG or open it and print to paper or PDF.
Complete NEMA 14-30 dryer plug wiring reference covering the four conductors, terminal assignments, grounding requirements, and key differences from older 3-wire dryer connections.
A 4-wire dryer connection uses a NEMA 14-30 receptacle and plug — the current North American standard for electric clothes dryers and other 240 V, 30 A appliances. The four conductors are: Line 1 (L1) — 120/240 V hot, typically black; Line 2 (L2) — 120/240 V hot, typically red; Neutral (W) — grounded conductor, white; and Ground (G) — equipment grounding conductor, green or bare copper.
The key distinction from the older 3-wire NEMA 10-30 connection is the separation of the neutral and ground conductors. In a NEMA 10-30 installation, neutral and ground were combined on a single conductor, and the dryer chassis was bonded to the neutral — an arrangement that permitted a neutral-to-ground fault to energise the dryer cabinet. The 4-wire system, now required by the National Electrical Code (NEC) for all new dryer circuits (NEC Article 250.140), uses a dedicated equipment grounding conductor. The dryer's internal bonding strap between neutral and ground must be removed when connecting to a 4-wire cord, because the chassis ground is now served by the separate green/bare conductor and must not be tied to the neutral terminal.
The NEMA 14-30 receptacle provides 240 V AC between L1 and L2 for the heating element, and 120 V AC between either hot leg and neutral for the motor, controls, and drum light. This dual-voltage requirement is why the neutral is essential even in a purely 240 V heating appliance — the dryer's low-voltage circuits depend on it.
Circuit protection requires a dedicated 30 A, two-pole breaker in the electrical panel. The branch circuit must be wired with 10 AWG (or 6 mm² metric equivalent) copper conductors in conduit or as 10/3 NM-B (non-metallic sheathed) cable where local codes permit.
How to wire 4 wire dryer plug diagram
- Verify the circuit and breaker rating Confirm the dryer circuit is served by a dedicated 30 A, two-pole circuit breaker in the electrical panel. The branch circuit must use 10 AWG copper conductors (4-wire: L1, L2, neutral, ground). Never share a dryer circuit with another outlet or appliance.
- Turn off the circuit breaker and verify dead Switch off the 30 A double-pole breaker supplying the dryer circuit. Use a calibrated non-contact voltage tester and a multimeter to verify that no voltage is present at the receptacle terminals before proceeding. Test L1-to-ground, L2-to-ground, and L1-to-L2.
- Remove the bonding strap inside the dryer (4-wire conversion) If converting from a 3-wire cord, open the dryer's terminal block access panel (usually at the rear). Locate the bonding strap or wire connecting the neutral terminal to the dryer chassis/frame. Remove this bonding connection entirely. The chassis will now be grounded exclusively through the separate green/bare ground conductor in the 4-wire cord.
- Connect the 4-wire cord to the dryer terminal block Feed the cord through the strain relief and into the dryer. Connect: white (neutral) to the centre terminal; black (L1) to the left terminal; red (L2) to the right terminal; green or bare (ground) to the chassis ground screw (a separate green screw or the frame ground lug — not the neutral terminal). Tighten all terminals to the torque specified in the dryer service manual.
- Install or verify the NEMA 14-30 wall receptacle If the wall receptacle is already a NEMA 14-30, verify its wiring: L1 (black) and L2 (red) to the two hot terminals; white (neutral) to the neutral terminal; green or bare to the ground terminal. The receptacle must be installed in a grounded metal or listed plastic electrical box, secured to the wall structure.
- Restore power and test Re-energise the circuit at the panel. Use a multimeter to verify voltage at the receptacle: 240 V AC between L1 and L2 terminals; 120 V AC between L1 and neutral; 120 V AC between L2 and neutral; 0 V AC between neutral and ground (confirm ground is not energised). Then plug in and run the dryer through a heat cycle.
Specifications
| Receptacle/plug standard | NEMA 14-30 (NEMA WD-6) |
|---|---|
| Rated current | 30 A |
| Rated voltage | 125/250 V AC (two-phase 240 V, with 120 V to neutral) |
| Minimum conductor size (copper) | 10 AWG (5.26 mm²) for 30 A circuit, 60 °C or 75 °C rated insulation |
| Circuit breaker requirement | 30 A two-pole (double-pole), listed for the electrical panel |
| Applicable code | NEC/NFPA 70, Article 250.140 (equipment grounding); Article 422 (appliances) |
| Conductor colour code (USA, NEC) | L1 = black; L2 = red; Neutral = white; Ground = green or bare copper |
| Bonding strap | Must be removed from dryer terminal block when using 4-wire (NEMA 14-30) cord |
Safety warnings
- Always turn off the dedicated dryer circuit breaker at the electrical panel and verify dead with a calibrated voltage tester before working on the receptacle or dryer terminal block. A 240 V shock from an energised 30 A circuit is potentially fatal.
- Remove the internal dryer bonding strap when converting from 3-wire to 4-wire. Failure to remove it connects the chassis to the neutral conductor — if a neutral fault occurs, the dryer cabinet will be energised at up to 120 V, presenting a serious electric shock hazard.
- Use only 10 AWG or larger copper conductors on a 30 A dryer circuit. Undersized wiring will overheat under load, damage insulation, and create a fire risk inside walls or conduit.
- The dryer branch circuit must be protected by a 30 A two-pole breaker — no more. An oversized breaker will not protect 10 AWG wiring from overcurrent and fire. Ensure the breaker is correctly rated and is a listed device for the electrical panel installed.
- All electrical panel work — adding or replacing breakers, connecting the branch circuit at the panel — must be carried out by a licensed electrician in compliance with NEC/NFPA 70 and applicable local electrical codes. Unpermitted electrical work can void homeowner insurance and create liability.
Tools needed
- Insulated screwdrivers (flat-blade 4 mm and 6 mm for terminal block screws)
- Digital multimeter with AC voltage function (200–600 V range)
- Non-contact voltage tester
- Wire strippers rated for 10 AWG conductors
- Lineman's pliers and side-cutting pliers
- Torque screwdriver or torque wrench (for terminal tightening to specified torque)
- Flashlight or work light (for working at panel and behind dryer)
Common mistakes
- Leaving the internal dryer neutral-to-chassis bonding strap in place when converting to a 4-wire cord — this defeats the purpose of the separate ground conductor and can energise the dryer cabinet on a neutral fault.
- Connecting the white neutral conductor to a hot terminal — a neutral-to-hot reversal in a 240 V appliance will damage the dryer's controls and motor and presents a fire risk.
- Using 12 AWG conductors instead of 10 AWG on a 30 A circuit — 12 AWG is rated for 20 A circuits; using it on a 30 A breaker means the wiring will overheat on load without tripping the breaker.
- Connecting the ground (green/bare) conductor to the neutral terminal instead of the chassis ground screw — this effectively creates an unsafe 3-wire arrangement within a 4-wire cord.
- Not using a strain relief at the dryer terminal block entry — without a strain relief, the cord can be pulled, putting tension on the terminal screws and eventually pulling conductors free inside the appliance.
Troubleshooting
- Dryer heats but drum does not turn (or vice versa)
- Cause: One hot leg (L1 or L2) is not providing 120 V — the heating element uses both legs (240 V) while the motor runs on one leg (120 V to neutral); a lost hot leg disables one function Fix: With the circuit live, measure voltage between each hot terminal and neutral at the receptacle. Both L1-neutral and L2-neutral should read approximately 120 V. If one leg reads 0 V, the circuit breaker or that leg's wiring has failed — turn off the breaker and investigate.
- Circuit breaker trips immediately when dryer is plugged in
- Cause: Short circuit in the dryer, cord, or receptacle wiring — or a single-pole breaker incorrectly used instead of a two-pole Fix: Unplug the dryer and reset the breaker. If the breaker holds, the fault is in the dryer or cord — inspect for damaged insulation or a pinched cord. If the breaker trips with nothing connected, the fault is in the branch circuit wiring — a licensed electrician must inspect and repair.
- Dryer case gives a slight shock when touched
- Cause: The internal dryer bonding strap was not removed during 4-wire conversion, and a neutral imbalance is present — or the ground conductor is not properly connected Fix: Immediately disconnect the dryer and check that the bonding strap has been fully removed and the green ground conductor is securely connected to the chassis ground screw, not the neutral terminal. Have the installation inspected by a licensed electrician before using the dryer.
Frequently asked questions
What is NEMA 14-30 and why is it used for dryers?
NEMA 14-30 is a 4-wire, 30 A, 125/250 V AC receptacle and plug configuration standardised for North American electric dryers and similar dual-voltage appliances. It provides two 120 V hot legs (giving 240 V between them for the heating element), a neutral (for 120 V control circuits), and a dedicated earth ground — satisfying modern NEC grounding requirements.
What is the difference between a 3-wire and 4-wire dryer connection?
A 3-wire NEMA 10-30 connection combines neutral and ground in a single conductor and bonds the dryer chassis to neutral — a safety compromise now prohibited in new installations. A 4-wire NEMA 14-30 connection separates neutral and ground, with a dedicated equipment grounding conductor, so a neutral fault cannot energise the dryer cabinet. The internal dryer bonding strap must be removed for 4-wire connections.
Can I convert my dryer from a 3-wire to a 4-wire cord?
Yes, if the dryer manufacturer's instructions permit it (most modern dryers are designed for both). The process involves replacing the 3-wire cord and plug with a 4-wire NEMA 14-30 cord and removing the internal neutral-to-chassis bonding strap. The 4-wire receptacle must also be installed at the wall if not already present. This work should be done by a licensed electrician.
What wire size is required for a 30 A dryer circuit?
A 30 A dryer circuit requires minimum 10 AWG copper conductors (approximately 5.26 mm²) in North America. In metric systems, 6 mm² copper is the nearest equivalent. Both hot legs, the neutral, and the ground must be the same gauge. Aluminium conductors require a larger gauge — consult NEC Table 310.12 for specific requirements.
Which terminal on a NEMA 14-30 plug is which?
On a NEMA 14-30 plug face viewed from the front (prong side): the straight vertical blade is Neutral (W/white); the two angled blades are L1 (left, black) and L2 (right, red); the rounded or U-shaped pin at the bottom is Ground (green/bare). Verify by consulting NEMA WD-6 or the plug body diagram.
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