The standard uses a factor, often denoted as $\epsilon$ (epsilon), to adjust the adiabatic current to account for heat loss. Deltarune | Quack Prep
Because the conductor is large (300 $mm^2$) and the duration is 1 second, heat escapes into the insulation. Let's say the calculation yields $\epsilon = 1.12$. Nonton Film Eternity 2010 Subtitle Indonesia
$$I_{AD} = K^2 \cdot A^2 / t$$