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    #46
    Originally posted by kwired View Post
    My guess is the majority of industrial single phase systems are rather low incident energy, more likely to be control circuit systems.

    But there is a lot of light industrial/light commercial that are supplied with single phase and large enough sources that you may have higher incident energy at least at your service equipment.
    Well I took a look at the new version of IEEE 1584-2018 today and section 4.11 states:
    4.11 Single-phase systems
    This model does not cover single-phase systems. Arc-flash incident energy testing for single-phase systems
    has not been researched with enough detail to determine a method for estimating the incident energy.
    I remain skeptical.
    Comments based on 2017 NEC unless otherwise noted.

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      #47
      Originally posted by tortuga View Post
      Well I took a look at the new version of IEEE 1584-2018 today and section 4.11 states:


      I remain skeptical.
      skeptical of what? It doesn't say there is no risk, just that it hasn't been investigated well enough that they chose not to publish any information on it.
      I live for today, I'm just a day behind.

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        #48
        Originally posted by kwired View Post
        skeptical of what? It doesn't say there is no risk, just that it hasn't been investigated well enough that they chose not to publish any information on it.

        I am skeptical that the requirement for a single main disconnecting means will enhance the safety of services.
        No incident reports were mentioned, like with AFCI's there were tons of residential fires that started in bedrooms.
        Huge costs will result to all services with substantiation of need only demonstrated for large 3 phase systems .
        UL 891, defines a switchboard enclosure to include all of the vertical sections within the stack. Each stack is a complete electrical
        enclosure. Changing 230.71 will add a huge cost switchgear installs.

        From the Statement of Problem and Substantiation for Public Input
        The six main rule for a single enclosure makes it impossible to work in service equipment when applying electrical safe work practices in accordance with NFPA 70E.
        That statement is not true for 240V single phase systems less than 125kVA. I can model a typical farm 800A single phase service with 6 main disconnects in a Siemens P4 panel-board, 200' from the power pole and maintain NFPA-70E, easily.
        Comments based on 2017 NEC unless otherwise noted.

        Comment


          #49
          Originally posted by tortuga View Post
          I am skeptical that the requirement for a single main disconnecting means will enhance the safety of services.
          No incident reports were mentioned, like with AFCI's there were tons of residential fires that started in bedrooms.
          Huge costs will result to all services with substantiation of need only demonstrated for large 3 phase systems .
          UL 891, defines a switchboard enclosure to include all of the vertical sections within the stack. Each stack is a complete electrical
          enclosure. Changing 230.71 will add a huge cost switchgear installs.

          From the Statement of Problem and Substantiation for Public Input

          That statement is not true for 240V single phase systems less than 125kVA. I can model a typical farm 800A single phase service with 6 main disconnects in a Siemens P4 panel-board, 200' from the power pole and maintain NFPA-70E, easily.
          It is not impossible to work in any six main equipment and comply with 70E. May be inconvenient but not impossible. If anything the supply can be killed.

          Good design might mean designing it so you don't have to kill everything to work on it and may drive cost up anyway.
          I live for today, I'm just a day behind.

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