A 480 VAC, 3 phase TEFC motor is to be installed on a floating platform. The area is classified as Class I, Division 2, Group D. The motor starter is in an explosion proof enclosure suitable for the classified area. Extra heavy duty cord with a grounding conductor will connect the motor with the starter. 501.10 (B)(2)(5) specifies a listed bushed fitting (not required to be specifically approved for Class I locations per handbook). Is a seal required between the starter enclosure and the motor?
Class I, Div 2 cord connected motor
- Thread starter sgunsel
- Start date
- Status
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
The rules for flexible cords are in 501.140; they apply to both Division 1 and 2. See 501.140(B)(5) for a specific answer. You may want to review 501.140(A) to determine whether you are permitted to use a flexible cord at all.(I suspect you will find it is permissible, but I don't know all the details)
rbalex, Thanks for the added reference, but it still remains a bit murky.
Assuming that the use of cord is permitted between the starter and the motor, 501.140(B)(5) requires seals, but then "Exception to (5): Seals shall not be required as provided in 501.10(B) and 501.105(B)(6)."
501.10(B)(2)(5) specifies that flexible cord listed for extra hard usage and provided with listed bushed fittings (not required to be specifically approved for Class I locations per handbook).
It appears that a listed bushing for the cord entrance to the enclosure is acceptable, but this is none too clear.
Assuming that the use of cord is permitted between the starter and the motor, 501.140(B)(5) requires seals, but then "Exception to (5): Seals shall not be required as provided in 501.10(B) and 501.105(B)(6)."
501.10(B)(2)(5) specifies that flexible cord listed for extra hard usage and provided with listed bushed fittings (not required to be specifically approved for Class I locations per handbook).
It appears that a listed bushing for the cord entrance to the enclosure is acceptable, but this is none too clear.
- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
If cord is otherwise premissible you will need a seal at the starter enclosure but not at the motor. This is basically a "build up" of 501.15(E)(1); i.e., the seal is for the integrity of the enclosure and not the cable.
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- Location
- Mission Viejo, CA
- Occupation
- Professional Electrical Engineer
In absence of formal definitions in the NEC itself, the NFPA Manual of Style (MOS) (Section 2.3.1.3.1) specifies Webster?s Collegiate Dictionary, 11th edition as the basis for words? ??ordinarily accepted meanings??
From Webster?s Collegiate Dictionary, 11th edition:
The basic principal to apply here is a regular cord connector will not maintain the integrity of an explosionproof enclosure; an appropiate seal must be used.
From Webster?s Collegiate Dictionary, 11th edition:
From the above relevant definitions, it would appear that, for the purposes of our discussion, the terms cord and cable are basically interchangeable; but in any case, all cords are cables.
The basic principal to apply here is a regular cord connector will not maintain the integrity of an explosionproof enclosure; an appropiate seal must be used.
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