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    250.122(B) revision

    1. 250.122(B)

    2. Add Text (In Italics)

    3. (B) Increased in Size. For circuits rated greater than 60-amperes, and where ungrounded conductors are increased in size, equipment grounding conductors, where installed, shall be increased in size proportionately according to circular mil area of the ungrounded conductors.

    4. For circuits rated under 30-amperes, increasing the EGC in proportion to the ungrounded conductor is unnecessary and results in the EGC being larger than what would be required for circuits using the same conductors on higher circuit ratings. For example, #10 AWG conductos are increased in size to #8. Per the current 2005 wording of the section, the EGC would be required to be increased to #8 as well. However, the same #10 AWG conductors could be used on a 40-ampere branch circuit with a #10 AWG EGC. If a #10 AWG EGC is sufficent for a 60-ampere circuit, where #6 AWG conductors are used for ungrounded conductors, why wouldn't #10 AWG EGC be sufficent on a 30-ampere circuit where #10 AWG conductors are used for ungrounded conductors.


    We have had this discussion on this Forum several times and think this issue merits a change.
    Bryan P. Holland, MCP
    NEMA - Codes & Standards

    #2
    Re: 250.122(B) revision

    OK Bryan, suppose you are running #6 Cu 3/C / #10 Ground for a long 60 ampere feeder and need to upsize the circuit conductors to #2 Cu, why wouldn't you need to upsize the #10? If the feeder was really that long to need to be that large, the grounding conductor would surely need to be larger as well to be effective.
    Charlie Eldridge, Indianapolis, Utility Power Guy[COLOR=red][/COLOR]

    Comment


      #3
      Re: 250.122(B) revision

      Okay, I agree. There is definitely a problem with this requirement under certain conditions. I just can't seem to figure out how to correct that issue.

      There must be a way to make the point that when certain conductors are increased to a certain size, the EGC may not need to be increased if it does not exceed the size shown in Table 250.122 for a circuit at ratings under 60-amperes.

      I will give it more thought, thanks.
      Bryan P. Holland, MCP
      NEMA - Codes & Standards

      Comment


        #4
        Re: 250.122(B) revision

        What's wrong with referencing it to 250.122?

        Comment


          #5
          Re: 250.122(B) revision

          bph - I know what you are getting at but I do not know how to word it either.

          I got into a situation where needed to run #6 for voltage drop using 30A branch ckts. for very long underground runs to parking lot light poles. Each pole had (4) 1000W HID luminaires.

          Do not remember exactly, but seems like I felt compelled to use #6 EGC also.
          Obviously #8 or even #10 EGC would have made it a little bit easier.

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            #6
            Charlie Eldridge, Indianapolis, Utility Power Guy[COLOR=red][/COLOR]

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