20 Amp Breaker — Wire Size, Max Load & NEC Guide
A 20 Amp breaker requires 12 AWG copper wire. Max continuous load: 16A (80% rule). Max watts: 1,920W at 120V or 3,840W at 240V.
20 Amp Breaker — Complete NEC Guide
20A circuits are required in kitchens, bathrooms, laundry rooms, and garages per NEC 210.11. Must use 12 AWG minimum. GFCI protection required in wet locations per NEC 210.8.
The 80% Rule (NEC 210.20)
A 20 Amp breaker has a maximum continuous load of 16A (20A × 80%). Continuous loads are those expected to run for 3 hours or more. If your load exceeds 16A continuously, upsize to the next standard breaker size. Non-continuous loads can use the full 20A rating.
Wire Sizing (NEC 310.16)
Per NEC Table 310.16 at 75°C: a 20 Amp breaker requires 12 AWG copper conductor minimum. For aluminum, upsize two gauges. For runs exceeding 75 feet, use 10 AWG to keep voltage drop under 3%. Verify with our Wire Size Calculator and Voltage Drop Calculator.
Common Uses for 20 Amp Circuits
Kitchen outlets, bathroom outlets, laundry, garage, outdoor outlets.
Disclaimer: This guide is for reference. All electrical work must be verified by a licensed electrician. Local codes may differ from NEC.
Frequently Asked Questions
All Breaker Sizes — Wire & Load Reference
| Breaker | Wire | Max Cont. | Max W (240V) |
|---|---|---|---|
| 15 Amp | 14 AWG | 12A | 2,880W |
| 20 Amp | 12 AWG | 16A | 3,840W |
| 25 Amp | 10 AWG | 20A | 4,800W |
| 30 Amp | 10 AWG | 24A | 5,760W |
| 40 Amp | 8 AWG | 32A | 7,680W |
| 50 Amp | 6 AWG | 40A | 9,600W |
| 60 Amp | 6 AWG | 48A | 11,520W |
| 70 Amp | 4 AWG | 56A | 13,440W |
| 80 Amp | 3 AWG | 64A | 15,360W |
| 100 Amp | 1 AWG | 80A | 19,200W |
| 125 Amp | 1/0 AWG | 100A | 24,000W |
| 150 Amp | 2/0 AWG | 120A | 28,800W |
| 200 Amp | 3/0 AWG | 160A | 38,400W |
| 300 Amp | 350 MCM | 240A | 57,600W |
| 400 Amp | 500 MCM | 320A | 76,800W |