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Thread: Class DIV1&2 free air nipple

  1. #1
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    Class DIV1&2 free air nipple

    I have a cable tray that runs from Class 1 DIV 2 through Class 1 DIV 1. The cable tray has a 1" and a 2"x24" nipple mechanically supported from the tray. The nipples are entering a NEMA 4X panel that is in a Class 1 Div 2 location with relays and other arcing devices and factory installed Class 1 Div 2 crouse breather screen drains. The kicker is that the nipple are free air, and never really get to the Class 1 DIV 1 area but are 8-11"s from the NFPA 70 class 1 div 1 boundary (20-23 TOTAL inches form the class 1 div 1 boundary). The nipples are open air but very close to the DIV 1 area and arcing devices. All of this is outdoors and does not have a roof or walls of any kind. Question: Do the nipples entering the Class 1 Div 2 NEMA 4X panel need seal offs?

  2. #2
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    Quote Originally Posted by pgallia View Post
    I have a cable tray that runs from Class 1 DIV 2 through Class 1 DIV 1. The cable tray has a 1" and a 2"x24" nipple mechanically supported from the tray. The nipples are entering a NEMA 4X panel that is in a Class 1 Div 2 location with relays and other arcing devices and factory installed Class 1 Div 2 crouse breather screen drains. The kicker is that the nipple are free air, and never really get to the Class 1 DIV 1 area but are 8-11"s from the NFPA 70 class 1 div 1 boundary (20-23 TOTAL inches form the class 1 div 1 boundary). The nipples are open air but very close to the DIV 1 area and arcing devices. All of this is outdoors and does not have a roof or walls of any kind. Question: Do the nipples entering the Class 1 Div 2 NEMA 4X panel need seal offs?
    I have a couple of questions of my own, before I answer this:

    1. What kind of cable is in the tray/nipples?
    2. Why isn't the panel "…with relays and other arcing devices..." explosionproof?
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #3
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    The cable is rated and not an issue. The panel was installed on the skid by the skid manufacture and the entire skid was inspected by UL and approved so that is on them. If it comes with is own UL cert# it has been deemed to be ready for use. They are frequently done incorrectly. My concern is the work that has to be done to tie it in at the facility not the SKID. The contractor has installed the nipples from the tray to the panel without seals. That is my area of question. I need a black and white NFPA 70 reference in this case, not an opinion or design help.

    Thanks

  4. #4
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    So far you have much bigger problems than the nipples. But, for what it's worth, sealing the nipples would be useless.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  5. #5
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    Quote Originally Posted by rbalex View Post
    So far you have much bigger problems than the nipples. But, for what it's worth, sealing the nipples would be useless.
    BUT, if you only want a black and white NEC response - read Section 501.15(E).
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  6. #6
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    Quote Originally Posted by pgallia View Post
    I have a cable tray that runs from Class 1 DIV 2 through Class 1 DIV 1. The cable tray has a 1" and a 2"x24" nipple mechanically supported from the tray. The nipples are entering a NEMA 4X panel that is in a Class 1 Div 2 location with relays and other arcing devices and factory installed Class 1 Div 2 crouse breather screen drains. The kicker is that the nipple are free air, and never really get to the Class 1 DIV 1 area but are 8-11"s from the NFPA 70 class 1 div 1 boundary (20-23 TOTAL inches form the class 1 div 1 boundary). The nipples are open air but very close to the DIV 1 area and arcing devices. All of this is outdoors and does not have a roof or walls of any kind. Question: Do the nipples entering the Class 1 Div 2 NEMA 4X panel need seal offs?
    So someone installed equipment in a C1D2 area that should not be there. Are you sure the contacts are not hermetically sealed? is it possible the contacts are protected in some other way such as with IS barriers?

    Quote Originally Posted by pgallia View Post
    The cable is rated and not an issue. The panel was installed on the skid by the skid manufacture and the entire skid was inspected by UL and approved so that is on them. If it comes with is own UL cert# it has been deemed to be ready for use. They are frequently done incorrectly. My concern is the work that has to be done to tie it in at the facility not the SKID. The contractor has installed the nipples from the tray to the panel without seals. That is my area of question. I need a black and white NFPA 70 reference in this case, not an opinion or design help.

    Thanks
    The control panel might have a UL label on it but I am doubtful that the skid itself is listed. I am not saying it is impossible, just unusual.

    I don't see how putting a seal on a non-explosion proof enclosure does any good.
    Bob

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