Yes the 40 ampere fuse is a device but you are not feeding it directly. You are feeding the 60 ampere switch which has the potential of having a 60 ampere fuses (device) installed in it. If we wee feeding a circuit breaker and terminating our tap on the circuit breaker, we would size oru tap to the circuit breaker. As to the ampere rating of the device terminations, 110.14 would have us using the 60 degree column for equipment 100 ampere or less unless identified for higher temperature rating. If we are using 90° rated conductors the ampacity must be selected from the 60° column when 60° terminations are used.
