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Thread: Class II Div 2 motors

  1. #1
    Join Date
    Jan 2006
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    2

    Class II Div 2 motors

    502.125 (B) Class II, Division 2 Motors lists 5 different types of motors (totally enclosed nonventilated,totally enclosed pipe ventilated, totally enclosed water-air-cooled, totally enclosed fan cooled, and dust ignitionproof). The final motor type listed in the list is dust ignition proof which is followed by a referrence to 500,8(C)(2). Is this reference valid for all 5 motor types are only for the dust ignition proof?

    Main question is really: Is the electrician required to hook up thermals on motors in a Class II Div 2 area? Argument is that a TEFC motor does not need to have thermals hooked up since it alreay is equipped with a fan to provide cooling and keep the external temp safe.

  2. #2
    Join Date
    Jul 2003
    Location
    PA/MD
    Posts
    191

    Re: Class II Div 2 motors

    jake,

    If the thermals you are referring to are thermal overloads, as I understand the code they are still required. NEC 2005, Article 430.31,
    "Part III specifies overload devices intended to protect motors, motor-control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start."

    Tony

  3. #3
    Join Date
    Oct 2004
    Location
    Rochester NY
    Posts
    122

    Re: Class II Div 2 motors

    I thought Jake was asking about the wires for the motors internal thermostat switch.
    Free is not the man who works for a living.

  4. #4
    Join Date
    Jan 2006
    Posts
    2

    Re: Class II Div 2 motors

    justdavemamm is correct, I am referring to the internal thermostat that is associated with the motor windings and case temperature.

  5. #5
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,061

    Re: Class II Div 2 motors

    Tony's answer is still correct. Some motors' "thermal-ratings" are based on the internal switches and they must be used in conjunction with the motor control circuits.

    In this particular case it has little to do with the Electrical Area Classification.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

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