Branch Circuit Calculator
Calculate electrical branch circuit parameters including wire size, breaker rating, voltage drop, and circuit loading for residential and commercial applications.
Step 1: Load Parameters
Understanding Load Types
Continuous loads (operating 3+ hours continuously) require the circuit to be sized at 125% of the load current according to NEC requirements.
Step 2: Circuit Parameters
About Wire Sizing
Proper wire sizing is critical for safety and performance. Undersized wires can overheat and cause fires. Always follow NEC (National Electrical Code) guidelines.
Branch Circuit Calculation Results
Recommended Wire Size
Wire Size Comparison
| Wire Size (AWG) | Ampacity (Cu/75°C) | Max Circuit Length | Voltage Drop |
|---|
Voltage Drop Analysis
Circuit Sizing Formula
Circuit Ampacity ≥ 125% of Continuous Load Current
For continuous loads (3+ hours), multiply load current by 1.25 to determine minimum circuit ampacity. Then select appropriate wire size from NEC tables.
Voltage Drop Formula
VD = (2 × K × I × L) / CM where K=conductor resistivity, I=current, L=length, CM=circular mils of conductor.
Need Professional Electrical Design?
Connect with our licensed electrical engineers for professional circuit design, load calculations, and NEC compliance verification for residential and commercial projects.
Get Professional Design