If you approach this strictly as a motor load, 430-104 requires the disconnecting means to "plainly indicate whether it is in the open(off)..." 430-109 Exception 2 would be the required disconnect (branch circuit breaker), since most of these exhaust fans have very small motors.
Or, if the fan is an appliance, which, IMO it is, then 422.31(A) applies iand you still end up with the branch breaker being the disconnect.
(and while I'm looking this up, IWire beats me to the punch)
[This message has been edited by Tom (edited 02-03-2005).]
Few things are harder to put up with than the annoyance of a good example.