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Class 1 Div 1/2 enclosure question

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warrenelec

Mechanical
Oct 31, 2003
37
i am working on a new design for an electrical termination box for an resistance element heater. i am using a killark box rated as explosion proof suitable for class 1/ div 1 hazardous areas. the box has a 2" NPT opening in the back of it & a 3/4" NPT opening on the side for rigid conduit attachment(installed by customer). the heater will be flange connected to a holding tank. i am welding a 2" pipe nipple to the flange and epoxy potting the tubular heating elements, whil containing all arcing contacts entirely within the killark enclosure. my thinking is that the 2" NPT potted nipple attached to the box is technically a "sealed conduit connection" so that the arcing contacts are located within the enclosure.
would the enclosure now be considered explosion proof & suitable for class 1 div 1 areas? i apologize if the post is unclear, the link below is a sketch of what i am trying to do. i understand that the entire heater may not be entirely explosion proof due to he possibility of high surface temps, but my concern right now is the just terminal enclosure being rated as explosion proof. all help is greatly appreciated.


 
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I think NEC 500.8(D)(1) states that Listed conduit, conduit fittings, or cable fittings shall be used for equipment provided with threaded entries. Your flanged section with pipe threads does not meet the requirements.

Plus, the piping, flange and epoxy potting are not listed devices.

The cable routing must be in conduit, with the proper seal.

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