Read the equipment markings
Use the lowest applicable termination rating at the connected equipment. Do not select 75°C or 90°C simply because the wire insulation carries that rating. The equipment listing and NEC 110.14(C) determine which column can be used.
Adjust the wire, then check the ceiling
For supported dual-rated THHN/THWN-2, PassPull starts with the 90°C ampacity for adjustment and correction, then caps the result at the selected terminal column.
With six current-carrying #10 copper conductors at 30°C, the adjusted figure is 40 A × 80% = 32 A. A verified 75°C terminal column allows 35 A, so 32 A controls. With a 60°C terminal column, 30 A controls instead. Ordinary small-wire protection remains a separate check.
When the marking is unclear
Check the equipment instructions and the applicable default provisions in 110.14(C), or ask the manufacturer or qualified reviewer. A guessed rating can change the outcome even when the conduit fill is identical.