If your breaker is rated for 10,000 Amps (10k AIC) but the AFC at that point is 22,000 Amps, the breaker could explode rather than trip safely during a fault.
Disclaimer: This blog post is for educational purposes. Always consult local electrical codes (NEC) and a licensed professional engineer for actual system designs. available fault current formula
Understanding Available Fault Current: The Formulas and Fundamentals If your breaker is rated for 10,000 Amps
| Scenario | Use Formula # | | :--- | :--- | | Rough estimate, no data | #2 (Transformer only) | | You know utility fault current | #3 (Limited Utility) | | Motors > 50 HP present | #4 (Add motor contribution) | | Fault is 100+ ft from transformer | #5 (Include conductor) | | Formal study for arc flash | #6 (Point-to-Point or IEEE 1584 software) | selecting breakers for a residential panel
Whether you are designing a switchboard, selecting breakers for a residential panel, or verifying an arc flash label, knowing how much current can flow during a short circuit is the foundation of safety.
Finally, we apply the multiplier to find the fault current at the end of that specific wire run.