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

Choosing the **what size wire for 220 volt 30 amp** circuit is one of the most common questions homeowners and DIYers ask before wiring a dryer, water heater, or workshop outlet. The wrong wire size can overheat, melt insulation, or fail inspection. This guide breaks down exactly what you need.

### **The Short Answer: 10 Gauge Copper**

For a standard 220-volt, 30-amp circuit, you need **10 AWG copper wire** or **8 AWG aluminum wire**. This applies to typical residential runs under 100 feet using NM-B (Romex) cable. Copper is the preferred choice for most installations because it handles heat better and connects more reliably.

### **Why Wire Gauge Matters for 30 Amps**

**Ampacity** is the maximum current a wire can safely carry. The National Electrical Code (NEC) rates 10 AWG copper at 30 amps in the 60°C column, which matches your breaker. Undersized wire creates resistance, and resistance creates heat — a leading cause of electrical fires.

Voltage Drop Over Distance

Long runs lose voltage. For every 100 feet beyond the first 100, consider upsizing to **8 AWG copper** to keep voltage drop under 3%. This keeps motors and heating elements running efficiently.

### **Copper vs. Aluminum Wire**

– **Copper:** Better conductivity, smaller size, preferred for 30-amp circuits.
– **Aluminum:** Cheaper but requires one size larger (8 AWG). Use only with AL-rated devices and antioxidant paste.

If you’re also connecting the receptacle end, follow this guide on what size wire for 220 volt 30 amp plug wiring to match your wire to the correct outlet.

### **Common 30-Amp Applications**

– Electric dryers (10-3 with ground)
– Tankless water heaters
– RV and welder outlets (NEMA 14-30R or 6-30R)
– Small subpanels and compressors

### **Frequently Asked Questions**

**Can I use 12 gauge wire for a 30-amp circuit?**
No. 12 AWG is rated for 20 amps only. Using it on a 30-amp breaker is a fire hazard and violates code.

**Do I need 10-2 or 10-3 wire?**
Use **10-3 with ground** for 240V circuits needing a neutral (dryers, ranges). Use **10-2 with ground** for pure 240V loads with no neutral.

**What about 8 gauge?**
8 AWG copper works fine and gives extra headroom for long runs, but it’s usually unnecessary for short distances.

### **Final Tips**

Always match your wire to the breaker, use proper connectors, and pull a permit when required. When in doubt, consult a licensed electrician. Getting the wire size right the first time protects your home and your equipment.

**Ready to wire it up? Double-check your gauge, then grab the right breaker and outlet before you start.**