“Exactly,” said Leo. “That breaker isn’t a protection device anymore. It’s a bomb. When that 72 kA fault occurs, the breaker will try to open, but the arc inside will be so violent it will vaporize the contacts, explode the casing, and turn the panel into a fireball. You won’t have a ‘short circuit.’ You’ll have a ‘long explosion.’”
“Imagine your utility grid is a massive water tank high on a hill,” Leo began. “That’s your infinite bus —an unlimited source. The pipe coming down the hill is your transmission line. At the bottom, you install a valve (your main breaker). Then you split the pipe into smaller ones for your factory. short ckt current calculation
[ I_{SC} = \frac{I_{Full\ Load}}{Z_{pu}} ] “Exactly,” said Leo