I have a boat lift that is wired with 8/3+insulated ground (240v). I want to add a subpanel at the lift to install a 120 outlet and future overhead lights. Initially, I will have a GFCI 240 breaker for the lift & a 120 breaker (not GFCI) to feed a GFCI outlet.

The breaker box has a neutral bar (grounding screw removed) and I added a separate ground bar to the box.

It is 150' from the main panel to the subpanel. The subpanel will be 50' from shore with no junction box at the shoreline. There is a junction box at the house 50' from the shoreline. Do I need to install additional grounding rods (?at the existing junction box?) or are the rods connected to the main panel sufficient?

  • 1
    Ground rods are required now for detached buildings, not sure about a sub panel not in the building, but usually the more ground rods the merrier. Your local building department should have the local codes you need to follow.
    – crip659
    Nov 14, 2023 at 20:58
  • Will there be an equipotential plane at this panel? (See NEC 682.33 although you may wish to consult with your AHJ as Article 555 does not require an equipotential plane in this application) Nov 15, 2023 at 1:36
  • IDK if the NEC requires it, but either way you should definitely want local ground rods. You do not want any possibility of exposed grounded metal (conduit, lift frame, etc.) that could be touched by somebody in the water being at a different voltage potential than the water - that's how electrocutions happen. You should really consider protecting the whole feeder with a GFCI breaker so any leakage into the water before the sub panel will immediately get cut off.
    – nobody
    Nov 15, 2023 at 1:37
  • Electricity near water. What could possibly go wrong? Nov 15, 2023 at 3:17


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