Standard ampacity charts assume "ideal" conditions (typically
Professional cable sizing is a four-step process. Skipping any step is a gamble. copper cable sizing
$I_z \ge I_b / (k_1 \times k_2 \times k_3)$ copper cable sizing
Can the cable handle the heat generated by the current? The cable has a base ampacity (current capacity) rating. However, this rating is almost always reduced (derated) by environmental factors. copper cable sizing