Thermal derating and conductor sizing
At 40 °C it derates to 18.8 A, at 50 °C to 17.4 A, and at 55 °C to 16.2 A — the upper end of its operating ambient range. Maximum power dissipation is 7.4 W, so thermal buildup in a tightly packed enclosure is manageable.
Mounting and environment
Mounts in any position — no derating needed for horizontal or inverted orientation. IP20 when installed in a distribution board with conductors connected; that's the standard for enclosed panel gear, not for open wet areas. The supply can enter from either top or bottom, which saves a rewire if the panel layout changes.