Safe Application of Totally Enclosed Motors in Hazardous Class I, Division 2 Locations

lt is common practice in the petrochemical industry to use nonlabeled totally enclosed motors rated 500 hp and below in Class I, Division 2 hazardous locations. Such motor applications meet the requirements of the National Electrical Code, and have proven over time to be safe. The Fine Print Note, [FPN] No. 1, in Article 501-8(b) of the NEC cautions users "to consider the temperature of internal and external surfaces which may be exposed to the flammable atmosphere" before applying the motor. The code in Section 501-8(b) does not differentiate between open and totally enclosed motors. This paper will discuss the role of motor internal as well as external surface temperature in determining if totally enclosed motors are safe for use in Class I, Division 2 locations. The implications of using adustable speed drives with TE motors will be discussed. Recommendations are proposed for changes to the NEC, user application criteria, and additional nameplate information to be provided by the motor manufacturer.