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Thread: Class I, Division I Seal-Off Controversy

  1. #11
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    If sealtight is an approved wiring method in this location, I am dubious of the seal requirement.

  2. #12
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    Quote Originally Posted by gadfly56 View Post
    What was the justification, other than it was someone's erroneous application of the precautionary principle? Did someone actually fill the section with an explosive mixture and spark it?
    Adding a guac is creating a bigger bomb by volume, its like putting your seal at 6' instead of 18". Enclosures and seals have limits to the explosion they can contain.

  3. #13
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    Quote Originally Posted by GHoffman View Post
    Pertaining to the attached picture, I received a call from the journeyman who installed the instrument and I need to clarify that the instrument was indeed in a c1d2 area. The problem that he has is that the instrument has external wiring much like a Murphy switch LS200. Problem in the field is most instruments having external wiring which have to have an immediate seal-off will have to require some sort of conduit body for terminating but with that would require a union (optional) and an additional seal-off on towards the raceway.
    So would it be: Instrument w/external wiring, seal-off, GUAC conduit body, c1d1 union, and 2nd seal-off?
    Am I right? Was hoping for more of a simpler scenario.
    Scooter
    501 is not that long of a section to read and analyze, c1d1 and c1d2 are night and day different, you are mixing some parts together. If splices stay below auto ig temp they don't need seals. The best way for you to have a better understanding is to read and analyze the sections, we honestly might just confuse you more. After you do that then ask remaining questions if any, just my suggestion. If instrument needs seal off you need one between it and guac per 17'nec anyway , if terms are below 80% ait in guac then you don't need sealoff between liquidtught and guac
    Last edited by Wire-Smith; 02-11-19 at 08:22 PM.

  4. #14
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    Quote Originally Posted by Wire-Smith View Post
    Adding a guac is creating a bigger bomb by volume, its like putting your seal at 6' instead of 18". Enclosures and seals have limits to the explosion they can contain.
    So, the answer to my question is "NO".

  5. #15
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    Quote Originally Posted by gadfly56 View Post
    So, the answer to my question is "NO".
    I think your question is based on a false pretense that it should be considered safe until proven unsafe, while in the industry we do it the opposite way, things have to be proven safe in the lab before we use them in public. I am guessing they never tested the different variations of the application, only 18" of multiple nipples. The guacs may blow the cover off when you get a combination like a big enclosure and a 1/2" conduit and guac, or those small instrument seals may blow with a big guac.

  6. #16
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    Quote Originally Posted by Wire-Smith View Post
    I think your question is based on a false pretense that it should be considered safe until proven unsafe, while in the industry we do it the opposite way, things have to be proven safe in the lab before we use them in public. I am guessing they never tested the different variations of the application, only 18" of multiple nipples. The guacs may blow the cover off when you get a combination like a big enclosure and a 1/2" conduit and guac, or those small instrument seals may blow with a big guac.
    It was previously approved. To my knowledge, and yours, no incident or series of incidents was brought to the attention of the committee that would suggest a move to a more restrictive requirement. The true implementation of the precautionary principal, is "Do nothing, unless clear evidence suggests otherwise". The false premise (not pretense) is that it should be considered unsafe until tested. Those advocating for a change from the status quo bear the burden of proof. Apparently, all we had were a bunch of busybodies looking for an excuse to justify their existence. And if you look at the draft report, it pretty much confirms my suspicions.

  7. #17
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    I think you should close this thread and start a new one entitled Class I Division II as you clarified. That is completely different and will likely remove the confusing and confused answers.


    I know what I don't know, and I know where to go to find it!

  8. #18
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    Quote Originally Posted by gadfly56 View Post
    It was previously approved. To my knowledge, and yours, no incident or series of incidents was brought to the attention of the committee that would suggest a move to a more restrictive requirement. The true implementation of the precautionary principal, is "Do nothing, unless clear evidence suggests otherwise". The false premise (not pretense) is that it should be considered unsafe until tested. Those advocating for a change from the status quo bear the burden of proof. Apparently, all we had were a bunch of busybodies looking for an excuse to justify their existence. And if you look at the draft report, it pretty much confirms my suspicions.
    Interesting view, it doesn't make sense to me. You say the premise I'm using is" unsafe until tested" I say" it is supposed to be proven safe beyond a reasonable doubt before being used on the public." just because it was put to the public before the doubt came about doesn't mean it is irrelevant. Explosions are a rare occurance but when they happen there are often extraordinary consequences. To me this isn't something to wait and see on, to me that would be like saying Russia and china have never attacked us, therefore we do not need to develop a specific defense plan against them. I will say though I know I am more on the conservative side of the scale on these kinds of issues and I'm not a good barometer of the industry if that makes you feel better.

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