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Thread: Submersible Pump Cable seal

  1. #1
    Join Date
    May 2012
    Farmington Hills, MI

    Submersible Pump Cable seal

    A wet well at a municipal pump station is classified as C1, D1. There are 4 submersible pumps with factory installed cables sealed at the pumps. Each cable has been routed through a separate conduit into a j-box. Each conduit is sealed within 18" of leaving the wetwell. The electrician that did this installation has separated the individual conductors at the seal fitting to seal the end of the cable. He stated the AHJ required this.
    My question: According to 501.15(D)(3), could the pump cable be considered a single conductor and sealed as such? How do you determine if a cable is capable of transmitting gases of vapors?

  2. #2
    Join Date
    Apr 2004
    Mission Viejo, CA
    Sections 501.15(D)(3) and 501.15(E)(2) were based on a product that was proposed, but not marketed; i.e., “gas-blocked” cable. Basically, cable manufacturers don’t want to make what UL wants to test. The concept is still valid, but no one certifies it.

    That said, in order to treat the multiconductor cable as a single conductor at the boundary, the installation you described would be an application of 501.15(D)(2), Exception. BTW, if the cable has "a gas/vaportight continuous sheath", only the end of the cable actually in the Division 1, location is required to be sealed. Check the UL "White Book" for cables that meet that criterion.
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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