Verified Mathematical Model & Formulation
Target Circular Mils = (2 × K × Distance (ft) × Current (A)) / Max Allowed Voltage Drop (V) Select AWG with Circular Mils ≥ Target CMil
Evaluates both thermal ampacity limits (NEC 310.16) and conductor resistance across distance to ensure wire meets both continuous fire safety and voltage drop constraints.
Configurable Parameters & Standard Units
- Circuit Voltage (V): (Default: 120 v)
- Load Current (A): (Default: 20 a)
- Run Distance (Feet): (Default: 100 ft)
Standard Worked Example & Practical Verification
Scenario: Installing a 48A continuous EV charger on a 240V 60A breaker over a 90-foot run.
Calculated Solution
6 AWG Copper Wire Required
Practical Takeaway: Always choose the larger gauge between ampacity requirements and voltage drop requirements.
Frequently Asked Questions
Why does long distance require thicker wire?
Wire resistance accumulates proportionally with length. Increasing wire gauge (larger cross-sectional area) reduces resistance, mitigating both voltage drop and heat buildup.