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Grounding requirements for solar powered Rectangular Rapid Flashing Beacon (RRFB)

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    Grounding requirements for solar powered Rectangular Rapid Flashing Beacon (RRFB)

    I will be installing a solar power Rectangular Rapid Flashing Beacon (RRFB) with 12V AGM (gel) or VRLA (voltage-regulated lead acid) output. The RRFB is located outside on the sidewalk. Do I have to ground/bond this system? I did not find any mention of this type of installation in NEC 2017 article 690.41. Could it be somewhere else? Also, will NEC 2020 have anything on this?
    I've attached a link for those of you that do not know what an RRFB looks like. https://www.youtube.com/watch?v=tEMYm8HUloY

    thanks

    #2
    I've not installed any of the RRFBs, but have on the solar powered school flashers, which are similar. The solar powered school flashers require a GEC and grounding electrodes.
    There is no difference in the code between this small system and a large commercial array. 690/41 is the grounding requirements for all systems. If the RRFB meets the definition of a PV system, then the rules in 690 are required to be followed. Not sure on the 2020 NEC, you can check the free version of the NEC at the NFPA website
    Moderator-Washington State
    Ancora Imparo

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      #3
      Originally posted by tom baker View Post
      I've not installed any of the RRFBs, but have on the solar powered school flashers, which are similar. The solar powered school flashers require a GEC and grounding electrodes.
      There is no difference in the code between this small system and a large commercial array. 690/41 is the grounding requirements for all systems. If the RRFB meets the definition of a PV system, then the rules in 690 are required to be followed. Not sure on the 2020 NEC, you can check the free version of the NEC at the NFPA website
      That s interesting, my first thought is it seems like its under 60 volts DC so it would be exempt under 250.162, however 690.43 states in part:
      "PV systems shall be grounded in accordance with 250.134 or 250.136(A), regardless
      of voltage." it does not seem to require the establishment of a grounding electrode system.
      250.136(A) might give you a bit of relief as the metal post could be considered grounded.
      Comments based on 2017 NEC unless otherwise noted.

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        #4
        Originally posted by tortuga View Post

        That s interesting, my first thought is it seems like its under 60 volts DC so it would be exempt under 250.162, however 690.43 states in part:
        "PV systems shall be grounded in accordance with 250.134 or 250.136(A), regardless
        of voltage." it does not seem to require the establishment of a grounding electrode system.
        250.136(A) might give you a bit of relief as the metal post could be considered grounded.
        "...regardless of voltage." That would mean those solar pathway lights you just stick in the ground... and the solar lights you can pin 'over any dark doorway' would need to be grounded as well.

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          #5
          Originally posted by PaulMmn View Post

          "...regardless of voltage." That would mean those solar pathway lights you just stick in the ground... and the solar lights you can pin 'over any dark doorway' would need to be grounded as well.
          Yes that is strange indeed, not its not requiring a grounding electrode system in 250.136(A). Even stranger would be those solar panel attic vent fans that have become popular.
          Comments based on 2017 NEC unless otherwise noted.

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            #6
            Ya'll need to look at 690.47. Arguably you need a grounding electrode. If the pole support can be metal going 10ft into the ground, that should be one way to do it. Or drive a rod and bond it to the pole.

            I personally think it would be somewhat overkill for an AHJ to require a grounding electrode for this particular item, but it ain't my decision, and there's no explicit exceptions in the code.

            Wouldn't hurt to ask the manufacturer what most people do. Note that if the battery negative (or positive) is supposed to be grounded, the manufacturer will probably have some instructions about how to do that.

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              #7
              The manufacturer said to follow NEC and NEC 690.43 says to ground PV systems regardless of voltage. Just wanted to see if there was an exception to this as it was in NEC 2014. thanks for your replies.

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