Breaker and Wire Size Calculator
'/%3E%3Ccircle cx='48' cy='39' r='19' fill='%23f2c9a5'/%3E%3Cpath d='M27 35c3-16 39-17 42 2-8-8-27-9-42-2z' fill='%23374151'/%3E%3Cpath d='M21 86c5-24 49-28 56 0z' fill='%232563eb'/%3E%3Ccircle cx='41' cy='41' r='2' fill='%23111827'/%3E%3Ccircle cx='55' cy='41' r='2' fill='%23111827'/%3E%3Cpath d='M42 52c4 3 9 3 13 0' stroke='%2392400e' stroke-width='3' fill='none' stroke-linecap='round'/%3E%3C/svg%3E)
Reviewed by Calculator Editorial Team
Determine the correct wire gauge and breaker size for your electrical circuit with our professional Breaker and Wire Size Calculator. This tool helps electricians and DIYers select the appropriate components for safe and efficient electrical installations.
How to Use This Calculator
Using our Breaker and Wire Size Calculator is simple:
- Enter the total circuit load in amperes (A)
- Select the voltage (120V or 240V)
- Choose the type of installation (residential or commercial)
- Click "Calculate" to get the recommended wire gauge and breaker size
The calculator will display the appropriate wire gauge (in AWG) and breaker size based on the National Electrical Code (NEC) standards.
Formula Explained
The calculation follows the NEC guidelines for determining wire and breaker sizes. The key factors considered are:
- Total circuit load (amperes)
- Voltage (120V or 240V)
- Type of installation (residential or commercial)
Wire Gauge Calculation
The wire gauge is determined based on the ampacity tables from the NEC, which consider the maximum current that a conductor can carry continuously under specified conditions.
Breaker Size Calculation
The breaker size is selected based on the wire gauge and the NEC requirements for overcurrent protection. The breaker must be at least as large as the wire's ampacity.
Worked Example
Let's calculate the wire and breaker size for a 20A circuit with 120V residential installation:
- Enter 20 for the circuit load
- Select 120V for the voltage
- Choose residential installation type
- Click "Calculate"
The calculator will recommend a 12 AWG wire and a 20A breaker for this circuit.
Important Note
Always verify your local electrical codes and consult with a licensed electrician for critical installations.
Common Wire and Breaker Sizes
Here's a reference table of common wire gauges and their corresponding breaker sizes:
| Wire Gauge (AWG) | Maximum Current (A) | Recommended Breaker Size |
|---|---|---|
| 14 AWG | 15 | 15A |
| 12 AWG | 20 | 20A |
| 10 AWG | 30 | 30A |
| 8 AWG | 50 | 50A |
| 6 AWG | 65 | 65A |
Frequently Asked Questions
What is the difference between wire gauge and breaker size?
Wire gauge (AWG) refers to the thickness of the wire, which determines how much current it can safely carry. The breaker size must match or exceed the wire's ampacity to provide proper protection.
Can I use a larger breaker than the wire's ampacity?
No, you should never use a breaker larger than the wire's ampacity. This can create a fire hazard as the wire may overheat and melt.
What factors affect wire and breaker selection?
The main factors are the total circuit load, voltage, installation type, and ambient temperature. Our calculator accounts for these factors to provide accurate recommendations.