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Thread: Process Area Bonding and Grounding within a Class 1 Div 2 Area

  1. #1
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    Process Area Bonding and Grounding within a Class 1 Div 2 Area

    There is some equipment within a classified area that I am not sure as to whether it should be grounded or not.

    There are several 55 gallon portable metal drums within the process unit, and they all hold flammable liquids. Should these be grounded?

    There are also several storage sheds, which are used to store some of these 55 gallon drums. Should the storage shed be grounded?
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  2. #2
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    The basic question is, "Would you ground/bond them if it wasn't a classified location?" There are a few other considerations. See Section 500.4(B) IN No. 3 for static and lightning.

    The NEC will only tell you how to ground or bond if it is required (Section 501.130); otherwise the requirements are no different than Article 250.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #3
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    Quote Originally Posted by rbalex View Post
    The NEC will only tell you how to ground or bond if it is required (Section 501.130); otherwise the requirements are no different than Article 250.
    did you mean 501.30?
    Bob

  4. #4
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    Quote Originally Posted by petersonra View Post
    did you mean 501.30?
    Yep - typo
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  5. #5
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    NFPA 77 may apply

  6. #6
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    Quote Originally Posted by shortcircuit2 View Post
    NFPA 77 may apply
    Yes, that's one of the references in Section 500.4(B) Informational Note No.3 that I mentioned in Post #2.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  7. #7
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    Quote Originally Posted by rbalex View Post
    Yes, that's one of the references in Section 500.4(B) Informational Note No.3 that I mentioned in Post #2.
    Yes, I see you did. I missed that.

  8. #8
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    After a brief look, I would say that per NFPA 77 Chapter 11, you should bond the drums to the filling station before filling. Also try to fill slowly, and at the bottom. However, I don't see any requirement nor reason why the tanks would need to be bonded all of the time.

    There doesn't seem to be any requirement for grounding in NFPA or elsewhere. Which makes sense since the drums are sitting on the ground, and will naturally dissipate charge through that contact.

    [Edit]: The above assuming the drums are fully metallic, and not lined with plastic or non-conductive coatings.

    I can't immediately think of any rationale for bonding the storage cages, and I don't believe I've seen that as a requirement anywhere. I would actually be more worried about an internal spark between the liquid and the drum - which is (hopefully) quite unlikely.

    You could also look at API RP 2003, but I'm pretty sure it says the same things.

    I also have a feeling there are a lot of places using flammable liquids in drums, and I've got the feeling that few to none of them bond or ground the drums on a regular basis (except, hopefully, for filling).
    Last edited by IntrinsicSafety; 05-03-18 at 05:13 PM.

  9. #9
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    Basic concept with NFPA 77 is to bond everything so equipotential is achieved.

  10. #10
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    Quote Originally Posted by shortcircuit2 View Post
    Basic concept with NFPA 77 is to bond everything so equipotential is achieved.
    That's what I tell people and its generally the most correct response. Granted, then you get people asking how they are supposed to bond glass sample bottles when dumping into a disposal barrel.

    API RP 2003 Section 4.6.4 covers your portable metal containers hazards.
    • "Portable metal containers should be bonded to the filling system..."
    • "...avoid splash filling..."
    • "...allow adequate residence time..."
    • blah blah blah


    For your remote waste barrels, your hazard there is mostly around the method and material you dump into it. Dumping a non-conductive sample that just got done splooshing around a bunch of piping may have a fairly decent static charge on it (see Section 4.1.3.2 for a similar scenario). Additionally, bonding it to some structural steel or a ground bar will decrease the static charge on any material tossed into the barrel before the next material gets tossed.

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