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    Propane pump seal off locations

    I am providing power to a booster pump that is hooked up to a set of propane tanks. The location is a firefighter training facility and the propane is used to start the fires in the various "props" that they use for training. Here's what I have done so far followed by the questions that I have.

    The panel that I am getting my power supply from is 160' feet away from the tanks and the pump. I ran 3/4" emt from the panel to a bell box outside. From the bell box I then ran 3/4" RMC underground all the way over to the classified location. This is where I am at now.

    The motor is listed for hazardous locations - class 1, group D and class 2, groups F & G.

    What I planned on doing was installing a disconnect and an on/off switch for the pump and I have 2 possible locations to do this. One location is only 6' from the edge of the propane tank. My interpretation is that if I go with this location I will have to use an explosion proof disconnect, explosion proof box and switch, as well as add seal offs. If I am correct so far my question is.

    1. Where all do I need to have the seal offs. On the line side pipe coming into the disconnect? On the load side pipe coming out of the disconnect? At the motor? Also am I ok with having EMT and a bell box 150' away and if so, do I need a seal between the bell box and the beginning of the RMC run?

    The second location is 45' away from the tanks and the pump motor and on the other side of the road. If I go with this location my interpretation is that I can use a regular NEMA 3 enclosure and can also just place the on/off switch inside of a bell box. If that is all correct then my thinking is that I would need a seal off on the conduit right before it goes underground to cross the road and another one once the conduit comes out of the ground next to the tank. I don't know if I need one at the pump or not since it is listed for the location.

    Any insight is greatly appreciated. I just need to know if I'm on the right track.

    #2
    This may sound petty but bear with me. Has the area classification been "properly documented" as required by Section 500.4(A) and what standard was used to determine the classification? See Section 500.4(B) IN No 2 for examples of potentially applicable standards. Your description does not lend itself to the Scope of Article 515.

    The following assumes we are dealing only with Class I, Division 2:
    1. The disconnecting means must still meet the requirements of Article 430, Part IX beginning in Section 430.101; especially Section 430.102 with respect to location.
    2. With respect to the EMT/RMC interface, proper grounding/bonding is essential. See Section 501.30.
    3. From your description, there will be at least one boundary seal. See Section 501.15(B)(2).
    4. Equipment seals will be per Section 501.15(B)(1). Pay special attention to which equipment is required to be explosionproof, it may refer you back to Class I, Division 1 requirements. The motor may or may not be required to be, even though it is, depending on Section 501.125(B).
    Last edited by rbalex; 07-16-19, 02:07 AM.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2017 NEC unless otherwise noted.

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