[lsaferite]

> For any electric appliance (including computers) which operates for 3hrs+ ("continuously"), the circuit rating is reduced to 80% capacity

That's a new one for me. Do you have a reference for that? I'd love to read more.

[ProllyInfamous]

NEC§210.20(A) a/k/a "80% Load Rule"

As trade practice, certain applications are ALWAYS deemed "continuous," e.g. water heaters, computers, space heaters, general lighting.