Page 2 of 2 FirstFirst 12
Results 11 to 13 of 13

Thread: Need clarification on 514.11 (Circuit Disconnects for Fuel Dispensing Facilites)

  1. #11
    Join Date
    Jan 2017
    Location
    North Dakota USA
    Posts
    62
    I was thinking about this post again, and I don't believe there is anything that says when the emergency stop button is pressed, that it needs to disconnect the neutral also. It does say that it needs to have a means to disconnect the neutral, along with the hots, and low voltage. This is for maintenance, not under an emergency situation. Please correct me if I am wrong.

  2. #12
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,900
    Quote Originally Posted by Dr Duke View Post
    I was thinking about this post again, and I don't believe there is anything that says when the emergency stop button is pressed, that it needs to disconnect the neutral also. It does say that it needs to have a means to disconnect the neutral, along with the hots, and low voltage. This is for maintenance, not under an emergency situation. Please correct me if I am wrong.
    OK. It's an emergency requirement. If it were only for maintenance, it would be a general requirement throughout hazardous locations - at least for Division 1.

    Basically, in an emergency all conductors to a dispenser must be isolated. The theory is there is a potential "surge" backfeed through the grounded conductor which could possibly arc in the Division 1 location. (Remember, the possibility, not necessarily the inevitability, of an arc is all that matters in Division 1.)

    Where you are right is the pushbutton itself need only be the actuator for the device(s) that actually perform the "means" for isolating the conductors.

    It should be noted this is a residual philosophy from the NFPA 30A Technical Committee and its predecessors and has been for many decades. Code Making Panel 14 has little control of the content of Article 514. They can only make sure it is not in direct conflict with the rest of Articles 500 to 504. See Sections 510.1 and 501.2.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  3. #13
    Join Date
    Jul 2015
    Location
    Wilmington, NC USA
    Posts
    272

    A little late

    A little late to this party, but I HATE shunt trip breakers for E-stops. It's a fail closed device and IMO should not be allowed for this purpose.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •