Dryer Wiring Diagram

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A dryer wiring diagram shows how to connect an electric clothes dryer to a 240V residential circuit, covering NEMA 14-30 four-wire and older NEMA 10-30 three-wire configurations and the differences between them.

An electric clothes dryer in North America operates on a 240 V, 60 Hz split-phase supply. It uses two hot legs (each 120 V to neutral) that together provide 240 V for the heating element, and the 120 V (one hot leg to neutral) for the motor, controls, and timer. The circuit is protected by a double-pole 30 A circuit breaker at the panel and wired with 10 AWG copper conductors.

There are two outlet and plug configurations in common use. The NEMA 14-30 is the current standard for new installations: it is a four-wire connection consisting of two hot conductors (L1 and L2), a neutral conductor (N), and a separate ground conductor (G). The outlet is rated 30 A, 125/250 V. The NEMA 10-30 is an older three-wire standard consisting of two hot conductors and a neutral — there is no separate ground conductor. In three-wire 10-30 installations, the neutral conductor serves as both the current-carrying neutral and the grounding conductor, with the dryer frame bonded to the neutral inside the appliance. This practice was accepted under earlier editions of the NEC but is no longer permitted for new installations per NEC 250.140 (exceptions apply to existing branch circuits that have not been modified).

When a dryer designed for a four-wire connection must be used on an older three-wire outlet, the dryer's internal bonding strap or wire that connects neutral to frame ground must be left in place (or installed, if it was removed for a four-wire installation). When a dryer is connected to a new four-wire outlet, the internal neutral-to-frame bond must be removed and the ground wire must be connected to the frame terminal — the neutral and ground conductors are separate from that point onward.

The dryer terminal block typically has four terminals: L1 (left hot), neutral (centre), L2 (right hot), and a ground lug (frame). Colour coding in North America: black — L1, red — L2, white — neutral, green or bare copper — ground. Conductor sizing for a 30 A dryer circuit requires 10 AWG copper (or 8 AWG aluminium, with aluminium-rated terminals and anti-oxidant compound).

Electric dryer wiring involves either a 3-wire or 4-wire 240 V supply depending on installation era and local code. A dryer motor wiring diagram adds another layer, showing how the drive motor, start winding, centrifugal switch, and door switch interrelate within the appliance. The outlet itself — whether a 3-prong NEMA 10-30 or a modern 4-prong NEMA 14-30 — dictates the cable and plug used. North American 240 V dryers use two hot legs (typically red and black), a neutral (white), and on 4-wire installs a separate ground (green or bare). Draw and annotate your dryer circuit in the free online editor to document the supply and internal motor connections in one place.

How to wire dryer wiring diagram

Determine the outlet type and dryer cord configuration needed Check whether the wall outlet is a NEMA 14-30 (four-wire, two hots + neutral + ground) or NEMA 10-30 (three-wire, two hots + neutral only). Match the dryer power cord to the outlet type. Purchase either a NEMA 14-30P or NEMA 10-30P dryer cord as needed.
Install or confirm the dedicated 30 A, 240 V circuit A dedicated 30 A double-pole circuit breaker must be installed in the panel. The circuit must be wired with 10 AWG copper (or 8 AWG aluminium) conductors from the panel to the dryer outlet. This work must be done by a licensed electrician with a permit.
Prepare the dryer's terminal block access Remove the back access panel on the dryer (typically 3–4 screws) to expose the terminal block. Identify the three or four terminals: L1 (usually left), Neutral (centre), L2 (usually right), and the ground lug on the dryer frame.
Configure the internal neutral-to-ground bonding for the cord type For a 4-wire NEMA 14-30 cord: remove the factory-installed bonding strap or wire that connects the neutral terminal to the dryer frame. For a 3-wire NEMA 10-30 cord: ensure the bonding strap is installed (connecting neutral terminal to frame), as the neutral serves as the ground path.
Connect the dryer cord conductors to the terminal block 4-wire NEMA 14-30: Black (L1) to left terminal, White (neutral) to centre terminal, Red (L2) to right terminal, Green or bare (ground) to the frame ground lug — not the neutral terminal. 3-wire NEMA 10-30: Black (L1) to left terminal, White (neutral) to centre terminal, Red (L2) to right terminal. No separate ground conductor in a 3-wire cord.
Secure the cord strain relief and replace the access panel Clamp the cord securely in the strain relief fitting on the back of the dryer so no pulling force reaches the terminal connections. Replace the access panel and all screws. Ensure the cord exits the dryer neatly and does not contact hot exhaust ducting.
Test the installation With the outlet de-energised, verify outlet polarity (in a 4-wire outlet: use a multimeter to check 240 V between L1 and L2, 120 V from L1 to neutral, 120 V from L2 to neutral, 0 V from neutral to ground). Plug in the dryer. Run a timed cycle and confirm heating and drum rotation function correctly.

Specifications

Supply voltage (North American electric dryer)	240 V AC, 60 Hz, split-phase (two 120 V hot legs)
Circuit breaker rating	30 A, double-pole
Conductor size	10 AWG copper (5.26 mm²) — all conductors; or 8 AWG aluminium with aluminium-rated terminals
Outlet configuration (new installations)	NEMA 14-30R: 30 A, 125/250 V, 4-wire (two hot, neutral, ground)
Outlet configuration (existing 3-wire, NEC 250.140 exception)	NEMA 10-30R: 30 A, 125/250 V, 3-wire (two hot, neutral — neutral serves as ground)
Typical dryer heating element power	4 000 – 5 600 W (240 V)
Typical dryer motor power	250 – 400 W (120 V, single-phase)
Maximum cord length	1.8 m (6 ft) per NEC 422.16 for dryer connections

Safety warnings

All new dryer circuit installations and any modification to existing circuits must be performed by a licensed electrician with appropriate permits and inspections by the authority having jurisdiction (AHJ), in compliance with NEC/NFPA 70. This diagram is for educational and reference purposes only.
Always switch off and lock out the 30 A double-pole breaker at the main panel before working on the dryer outlet, dryer cord, or terminal block. Verify zero voltage at all outlet terminals with a calibrated CAT III/IV voltage tester before touching any conductor.
240 V exposure can cause fatal cardiac arrest at very low current levels. Never assume a circuit is de-energised based on breaker position alone — always verify dead with a tester.
The neutral-to-frame bonding strap configuration is critical. On a 4-wire NEMA 14-30 connection, the bonding strap MUST be removed. Leaving it in place allows fault current to flow back through the neutral conductor and energise the dryer frame relative to true ground, creating a shock hazard on the appliance body. On a 3-wire NEMA 10-30 connection, the bonding strap MUST be present.
Do not use extension cords for dryer connections. The 30 A current draw exceeds the rating of standard extension cords, causing overheating and fire risk. The dryer power cord must connect directly to the wall outlet.
NEMA 10-30 (3-wire) outlets must not be installed in new construction or new branch circuits. Existing 3-wire dryer outlets may remain in use only on unmodified existing branch circuits as permitted by NEC 250.140 exception. Consult a licensed electrician regarding any upgrade.

Tools needed

Calibrated CAT III/IV voltage tester and digital multimeter
Insulated screwdrivers (flat-head for terminal block screws)
Nutdriver or socket wrench (for strain relief)
Wire stripper (sized for 10 AWG conductors)
Non-contact voltage tester
Flashlight or headlamp (for working inside the dryer access panel)

Common mistakes

Leaving the neutral-to-frame bonding strap installed when converting from a 3-wire to a 4-wire cord, energising the dryer frame at neutral potential and creating a shock hazard.
Connecting the ground conductor to the neutral terminal (centre) instead of the ground lug on the dryer frame in a 4-wire installation, defeating the purpose of the separate ground.
Using a 3-wire dryer cord on a 4-wire outlet, or vice versa, by altering the outlet or cord — both the outlet and cord must match the installed branch circuit wiring type.
Not tightening the terminal block screws to the manufacturer's specified torque, causing a high-resistance connection that arcs and overheats under the 30 A load.
Not securing the cord in the strain relief, so mechanical stress on the cord is transmitted directly to the terminal block connections, eventually loosening them.
Installing a 30 A outlet on a circuit breaker of incorrect rating, for example a 20 A breaker — the breaker will not adequately protect the 10 AWG conductors and the dryer will trip the breaker during normal operation.

Troubleshooting

Dryer runs but does not heat: Cause: One hot leg (L1 or L2) is missing — open connection at the outlet, blown leg in the panel, or a loose terminal. The motor runs on 120 V from the remaining hot leg to neutral, but the 240 V heating element has no supply. Fix: Measure voltage at the dryer terminal block (or outlet): should be 240 V between L1 and L2, 120 V from each hot to neutral. If only 120 V is present between L1 and L2, one hot leg is open. Check the double-pole breaker (both halves must trip together and reset together); check for loose outlet terminals.
30 A breaker trips during dryer operation: Cause: Dryer heating element has partially failed and is drawing excess current, a conductor is partially short-circuited, or the breaker itself has a reduced trip threshold due to age or damage Fix: Turn off the breaker, disconnect the dryer cord from the outlet. Measure the resistance of the heating element (at the dryer terminal block). An open circuit means a failed element. A very low resistance means a shorted element. If element resistance is correct, check for conductor insulation damage. Measure breaker trip current if element and wiring are clear.
Dryer gives mild electric shock on touch: Cause: Dryer frame is energised, typically because the neutral-to-frame bonding strap was incorrectly left in on a 4-wire installation, or the equipment ground is not properly connected Fix: IMMEDIATELY switch off the breaker. Do not use the dryer again until an electrician inspects it. Measure voltage from the dryer frame to a known good ground. If voltage is present, the neutral-to-frame bond is incorrectly installed or the ground conductor is not connected. This is a serious shock hazard.

Frequently asked questions

What is the difference between a 3-wire and 4-wire dryer connection?

A 3-wire NEMA 10-30 connection has two hot conductors and a neutral — no separate ground. The neutral doubles as the ground path. A 4-wire NEMA 14-30 connection adds a separate ground conductor, so neutral and ground are independent paths. Four-wire is the current NEC requirement for new dryer circuits; 3-wire is only permitted on unmodified existing branch circuits under NEC 250.140.

Can I change a 3-wire dryer cord to a 4-wire cord?

Yes, but the dryer's internal wiring must also change. On a four-wire connection, the bonding strap or wire connecting the neutral terminal to the dryer frame must be removed, and the separate ground conductor from the cord must be connected to the frame ground lug. Leaving the neutral-to-frame bond in place on a four-wire installation creates a shock hazard.

What wire gauge do I need for a dryer circuit?

A standard 30 A electric dryer circuit requires 10 AWG copper conductors (or 8 AWG aluminium with aluminium-rated terminals). The circuit is protected by a 30 A double-pole circuit breaker. Some larger or combined washer-dryer units may require a 40 A or 50 A circuit — always check the appliance nameplate.

What NEMA outlet do I need for a dryer?

For new installations per current NEC requirements: NEMA 14-30R (30 A, 125/250 V, four-wire: two hots, neutral, ground). The matching plug on the dryer cord is NEMA 14-30P. For older homes with an existing 3-wire outlet: NEMA 10-30R (30 A, 125/250 V, three-wire). Do not install a new NEMA 10-30 outlet — use only NEMA 14-30 for all new work.

Can the dryer circuit share a breaker with other appliances?

No. NEC 220.14 requires that a dedicated branch circuit be provided for a clothes dryer. The 30 A, 240 V dryer circuit must serve only the dryer outlet and no other outlets or loads. Sharing the circuit with other appliances would create an overloaded circuit and could trip the breaker during dryer operation.

What does a dryer motor wiring diagram show?

A dryer motor wiring diagram illustrates the internal connections of the drive motor: the main run winding, the start winding with its centrifugal switch (which disconnects the start winding once the motor reaches operating speed), and the thermal overload protector. It also shows how the door switch interrupts the motor circuit when the door is open, and how the timer or electronic control board switches power to the motor and heating element independently. Consulting this diagram is essential when diagnosing a motor that hums but does not spin (open centrifugal switch or start winding fault).

What does a dryer outlet wiring diagram show?

A dryer outlet wiring diagram shows the wiring from the breaker panel to the wall receptacle. A modern 4-wire installation (NEMA 14-30R) uses a double-pole 30 A breaker feeding two hot wires (L1 red, L2 black), a neutral (white), and a separate equipment ground (green or bare copper) — all four terminate in the outlet. An older 3-wire installation (NEMA 10-30R) omits the separate ground, with the neutral bonded to the appliance frame at the terminal block. Local electrical codes in most regions now require the safer 4-wire arrangement for new installations.

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