FREE REFERENCE
Breaker & Wire Size Chart
The reference table every homeowner Googles mid-project — with straight answers on when to stop DIYing.
Breaker Size → Wire Size (Copper)
| Breaker Size | Copper Wire (THHN/NM) | Typical Uses |
|---|---|---|
| 15 amp | 14 AWG | Lighting circuits, bedroom outlets |
| 20 amp | 12 AWG | Kitchen & bath outlets, garage, microwave |
| 30 amp | 10 AWG | Electric dryer, water heater, RV outlet |
| 40 amp | 8 AWG | Electric range, larger AC units, EV charging (32A) |
| 50 amp | 6 AWG | Ranges, spas, EV charging (40A), welders |
| 60 amp | 6–4 AWG | Sub-panels, EV charging (48A), large AC |
| 100 amp | 3–1 AWG | Sub-panels, casitas, workshops |
| 200 amp | 2/0 copper / 4/0 aluminum SE | Main service |
The rule underneath the table: the breaker protects the wire, not the appliance. When in doubt, bigger wire is always safe; a bigger breaker never is.
Common Circuits Cheat Sheet
| Appliance / Circuit | Typical Breaker | Notes |
|---|---|---|
| Central AC (3–5 ton) | 30–60 amp (2-pole) | Match the unit’s nameplate — not a guess |
| Electric dryer | 30 amp (2-pole) | 10 AWG, 4-prong outlet on new work |
| Electric range/oven | 40–50 amp (2-pole) | 8–6 AWG |
| EV charger (Level 2) | 40–60 amp (2-pole) | 80% rule: 48A charging needs a 60A circuit |
| Microwave (built-in) | 20 amp dedicated | 12 AWG |
| Dishwasher / disposal | 15–20 amp | Often dedicated; GFCI in current code |
| Pool pump | 20 amp (typically 2-pole) | GFCI-protected, bonded |
| Bathroom outlets | 20 amp GFCI | Required dedicated in modern code |
Modern code adds requirements these tables can’t capture — AFCI/GFCI protection, dedicated circuits, and derating for conduit fill and Arizona attic temperatures. That’s the part licensed electricians carry in their heads.
FAQ
Common Questions
Can I put a bigger breaker on the same wire to stop trips?
Never. Breaker size exists to protect the wire — a 30-amp breaker on 14-gauge wire lets the wire cook inside your wall before the breaker notices. If a circuit trips constantly, the fix is finding the overload or running a new circuit.
Copper vs. aluminum wire sizes — why the difference?
Aluminum conducts less per size, so it must be thicker for the same amperage (e.g., 4/0 aluminum vs 2/0 copper for a 200A service). Aluminum is standard and safe for large feeders; it’s the old small-gauge aluminum branch wiring that causes trouble.
Do these charts make DIY electrical legal in Arizona?
Homeowners can pull permits for some work on their own primary residence, but anything beyond a like-for-like swap deserves a licensed hand — and unlicensed paid work over $1,000 is illegal in Arizona. Use the charts to understand your system and check the work you hire.
Project Bigger Than a Chart?
Flat-rate circuits, permits included, done right.