## What Size Wire for 220 Volt 30 Amp? The Complete Guide

Choosing the wrong wire size for a 220-volt, 30-amp circuit is one of the most common—and most dangerous—mistakes in DIY electrical work. Undersized wire overheats, melts insulation, and can spark a house fire. Oversized wire wastes money and is hard to bend into tight boxes. This guide gives you the exact answer, plus the code rules and practical tips you need to wire safely and legally.

### The Short Answer: 10 AWG Copper

For a standard 220V 30-amp circuit, use **10-gauge copper wire**. This holds true for runs up to roughly 100–150 feet. Copper 10 AWG is rated for 30 amps at 60°C, which matches the typical breaker and receptacle rating.

If you prefer aluminum, you need **8-gauge aluminum** to carry the same 30 amps safely. Aluminum has lower conductivity, so it requires a larger size. For most residential projects, copper is the better choice.

### Why Wire Gauge Matters

Wire size determines how much current a conductor can carry without exceeding its temperature rating. The National Electrical Code (NEC) publishes ampacity tables (310.16) that list safe current limits for each gauge and insulation type.

A 30-amp breaker protects the circuit at 30 amps. If the wire can only handle 20 amps, the breaker won’t trip before the wire overheats. That’s how fires start.

### Voltage Drop Over Distance

Long runs lose voltage. The NEC recommends keeping voltage drop under 3% for branch circuits. For a 220V circuit, that’s about 6.6 volts.

At 30 amps, 10 AWG copper has a voltage drop of roughly 3.6% per 100 feet. So beyond about 100 feet, consider stepping up to **8-gauge copper**. This keeps your tools and appliances running at full power.

### Matching Breaker, Wire, and Receptacle

All three components must agree:

– **Breaker:** 30 amps, double-pole for 220V
– **Wire:** 10 AWG copper (or 8 AWG aluminum)
– **Receptacle:** NEMA 6-30R or 14-30R, rated 30 amps

A NEMA 14-30R includes a neutral, needed for dryers and some welders. A NEMA 6-30R has no neutral and suits pure 240V loads like air compressors. Always match the plug to the receptacle.

If you’re unsure how to connect the plug safely, this step-by-step guide on [what size wire for 220 volt 30 amp](https://www.dtcee.com/220v-30-amp-plug-wiring-5-fast-safe-steps-to-connect/) walks you through the wiring process.

### Insulation Type and Temperature Rating

Ampacity depends partly on insulation. Common types:

– **NM-B (Romex):** 60°C rating, 30A for 10 AWG
– **THHN/THWN:** 75°C or 90°C, higher ampacity

In conduit, THHN 10 AWG can handle more current, but you still size to the 60°C column for most residential work. Check your local code.

### Aluminum vs. Copper

Copper conducts better, resists corrosion, and bends easily. Aluminum is cheaper and lighter but needs antioxidant paste and larger gauges. For a 30-amp 220V circuit, copper 10 AWG is the standard, simplest choice.

### Common Applications

A 220V 30-amp circuit powers:

– Electric dryers
– Small welders
– Table saws and shop tools
– Air compressors
– Ranges