unused cable grounding

I have a pair of 2/0 cables running underground from my solar room to an outbuilding about 60 feet away.  They used to attach to the batteries to bring 12v for lighting in the outbuilding.  Over the years my solar has evolved to 48 volts and I no longer use the cables.  Then can't be removed.  They are unattached and open ended in the solar room, but still connected to an unused circuit breaker panel in the outbuilding.  I would imagine these wires would present a possible problem if we were to be struck by lightning.  Should I detach both ends and ground both the unused wires in the Solar room for lighting protection?  Thanks.


  • Graham ParkinsonGraham Parkinson Registered Users Posts: 73 ✭✭
    The main source of voltage and thus currents in the cables would be from differing ground potentials at each end of the cables in the event of a nearby strike.   If the ends are not near wiring in use it would be unlikely to cause problems. But cutting them back and detaching both ends from anything connected to circuits in use will help.

    As to grounding the ends in the solar room, not sure this really helps, by grounding you are creating a current path into the solar room that may increase chances of inducing damage in nearby circuits. If you must ground in your  solar room - I would ground to something as far as possible from the ground used by your solar gear.  If they were connected to the same ground there might be an argument that a large pulse of current collected by the 60 foot long conductors (antennas) might raise the ground potential of the solar room ground and your gear enough to cause damage.

    But given that the cables are buried and surrounded by a ground, during a large megavolt pulse the insulation would probably just breakdown at say 600V and charge would flow into the ground.

    I would not worry about it too much!

    Offgrid in cloudy PNW

    MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install ....

  • mike95490mike95490 Solar Expert Posts: 9,363 ✭✭✭✭✭
    edited July 9 #3
    I'd disconnect each end, and put a wire nut on it.

    Preserve the cables in case in 5 years, you need more wire
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  • BigwoooBigwooo Solar Expert Posts: 62 ✭✭
    Thank you for the replies.  I'll definitely keep the cable available, never know.  Just make sure the ends are not near any wiring.
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