How to Wire a 4-Prong Plug? | Avoid The Common Mistakes

A 4-prong plug wiring job lands two hot wires, a neutral, and a ground on the matching terminals — black/red to brass, white to silver, green to green.

Most 4-prong plugs in a U.S. home belong to an electric dryer or range, and the circuit runs at 120/240 volts. How to wire a 4-prong plug comes down to four conductors landing on the right terminals, in the right order, with the power off.

4-Prong Plug Wiring: The Terminal Map That Matters

Each of the four conductors in a 4-prong plug has a specific landing point: two hot wires, one neutral, and one ground. The terminal labels on the receptacle or plug housing make the mapping clear once you know what they mean.

The Spruce’s range cord guide uses the same mapping: white to the center neutral terminal, black and red to the hot terminals, and green to the ground screw on the appliance body.

Wiring Sequence, Step By Step

The straight sequence is stable across dryers and ranges: disconnect power, open the housing, strip, connect, secure, and test. Follow it in order and you’re working on a dead circuit the whole time.

1. Turn off the breaker for that circuit and confirm the appliance is de-energized.
2. Open the plug or receptacle housing to expose the terminals and their labels.
3. Strip about 1/2 inch of insulation from each conductor.
4. Land each wire on its matching terminal — black to X, red to Y, white to W, green to G — and tighten each screw firmly. No exposed strands should remain outside the terminal.
5. Install and tighten the strain relief before closing the housing. Maytag’s video on connecting a 4-wire power supply cord shows this order and stresses a UL-listed strain relief rated for the cord.
6. Reassemble the cover securely. The cord should sit snug in the strain relief with no wiggle.
7. Test continuity with a multimeter or continuity tester before you flip the breaker back on.

If you’re converting an old dryer from a 3-wire cord to a 4-wire one, the green screw holding the neutral-to-frame bond must be removed, per Maytag’s installation video. The center white wire and the cord’s neutral then join on the center terminal.

What Happens If You Wire The Neutral And Ground Backwards?

Reversing neutral and ground turns the appliance chassis into a live conductor under fault conditions, which is exactly the shock and fire hazard a 4-wire system exists to prevent. The white neutral and the green or bare ground are not interchangeable.

The other frequent error is leaving the old neutral-ground bond in place on a 4-wire dryer conversion — the Maytag video specifically calls that out. An omitted or loose strain relief is another cited hazard, along with under-tightened screws and exposed strands. Before you start, make sure your cord actually matches the outlet; mix up a NEMA 14-30 dryer plug with a NEMA 14-50 range plug and nothing fits. If you’re shopping for a new cord, our tested 4-prong plug recommendations cover UL-listed options that match either receptacle.

FAQs

Can I swap the black and red wires on a 4-prong plug?

On many 120/240-volt appliances, the two hot legs are not polarity-sensitive, so swapping black and red won’t hurt the device if the manufacturer allows it. Always check the appliance manual before trying it. If the documentation doesn’t address it, land them exactly as labeled.

What does the green screw do on a dryer’s wiring?

The green screw is the equipment ground connection point. On a 4-wire installation, the green or bare wire lands there, and the separate grounding conductor carries fault current safely to the panel. On an older 3-wire dryer, that screw held the neutral-to-frame bond; removing it is required when upgrading to 4-wire.

Can I use a 4-prong cord on a 3-prong outlet?

No. A 4-prong plug physically won’t fit a 3-prong receptacle, and adapting one is unsafe because the 3-wire system lacks a separate ground conductor. You’d need to replace both the cord and the receptacle, and changing the outlet may require updating the branch circuit wiring to code.