Thanks for your reply Bob. I am not finding Sec. 501.10(C) in either the NEC 2008 or 2011 editions. Is it possible you were referring to 501.10(B)(3). Also, since the section I just referred to mentions "simple apparatus", can a Honeywell tach sensor be installed in a Class1, Div 2 location and be considered as nonincendive without a control drawing? My inclination is no. I would think that if you cannot use Class1, Div 2 wiring methods, then to use the sensor, plus the associated wiring that goes into the hazardous location, it would have to be approved by a Third Party Testing Agency (NRTL) to be considered as a nonincendive circuit.