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Thread: C1D2 Connectors

  1. #1
    Join Date
    Jun 2016
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    Evansville, IN, USA
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    C1D2 Connectors

    I am retrofitting and existing system with controls upgrade. The application is that I am purging & pressurizing (type Z) a panel that will have connectors on it.

    I have a connector that only has IS circuits in it. Since I'm using IS barriers, I should be able to use normal wiring methods. However after a brief search, I see that Harting sells an Intrinsically safe connector, but I can't really see much difference between it and a regular connector. Do I have to have a special connector for an intrinsically safe circuit, or can I use a regular connector?

    I also have motors that will be fed from this panel. Even though the panel is purged, I still have to use a C1D2 Plug or better because the Purge and pressure are on the inside of the panel and the connector is on the outside, correct? The purge and pressure will not cover a plug connected to the panel.

  2. #2
    Join Date
    Apr 2004
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    Mission Viejo, CA
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    5,230
    I have read and reread the OP several times. I assume the panel's exterior location is Class I, Division 2 as implied by the Type Z purge. I further assume the exterior atmosphere has been properly classified and properly documented as required by Section 500.4(A). I assume the Type Z purge meets the requirements of NFPA 496.

    A few comments:

    • Intrinsically Safe (IS) barriers alone do not necessarily guarantee an IS circuit. [See Section 504.10(A)] That is, without a proper control drawing, it isn't a IS System.
    • I looked at the Harting connectors. They are IS [Ex i] rated because they are only suitable for use in an IEC IS application. They do not meet the NEC "Zone" requirements of Section 505.9; particularly 505.9(B) and 505.9(C)(2). Many European manufacturers still haven't learned that meeting the ATEX Directive doesn't make their product suitable for US domestic markets.
    • Depending on the actual air flows, the purged enclosure may in fact be suitable protection for the connectors/plugs. Otherwise a listed Division 2 connector/plug must be used.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #3
    Join Date
    Jul 2017
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    Alberta, Canada
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    Quote Originally Posted by msshel0 View Post
    I have a connector that only has IS circuits in it. Since I'm using IS barriers, I should be able to use normal wiring methods. However after a brief search, I see that Harting sells an Intrinsically safe connector, but I can't really see much difference between it and a regular connector. Do I have to have a special connector for an intrinsically safe circuit, or can I use a regular connector?
    I assume the connector is in the purged panel.

    The equipment standards (as well as the NEC) say that IS circuits have to be kept separated from each other. This obviously applies everywhere. So this implies that the connector would have to be evaluated against UL 913 / UL 60079-11 and certified as intrinsically safe equipment.

    This would be true regardless of if the connector lives in the purged panel or not. If circuits cross-connect inside the panel, it will affect the intrinsic safety of the equipment oustide the panel.

    The "intrinsically safe connector" has probably been evaluated to only a few parts of one standard. Hopefully, one of those parts is creepage/clearance distances. If the connector meets the creepage/clearance distances of UL 60079-11, you can run multiple IS circuits through it and they won't be able to short-circuit to each other. But you'd better carefully research exactly what that "intrinsically safe" connector has and has not actually been certified to.

    Alternatively, you could ditch the connector and just run individual screened cables, thus (hopefully) avoiding the question altogether.

    Quote Originally Posted by msshel0 View Post
    I also have motors that will be fed from this panel. Even though the panel is purged, I still have to use a C1D2 Plug or better because the Purge and pressure are on the inside of the panel and the connector is on the outside, correct? The purge and pressure will not cover a plug connected to the panel.
    Yes, correct. Anything outside the purged envelope is not purge protected, and has to meet an alternative form of protection.

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