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Thread: Lights on in flooded house

  1. #1
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    Lights on in flooded house

    How is it that a house in the 3' of flood water still has a front porch light ON? (picture from Harvey Flood) How can a submerged circuit, both grounded & ungrounded conductors, not trip the breaker? How can you have all these energized wires in the water and not electrocute everyone around?

  2. #2
    Join Date
    Jul 2006
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    2,383
    Some combination of good insulation, no GFCI on the circuit, low-conductivity water, and terminals that aren't in the water.

    Even dirty fresh water doesn't conduct well and at 120v isn't likely to conduct enough to trip the breaker.

  3. #3
    Join Date
    Feb 2012
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    Washington State
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    That would depend on the branch the porch light was on.

    Energized conductors separated by a few feet won't necessarily trip a breaker, either...figuring for resistance of the circuit.
    Kirchoff and Ohm...the only laws that make sense

  4. #4
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    Apr 2009
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    Quote Originally Posted by RomexRocket1 View Post
    How is it that a house in the 3' of flood water still has a front porch light ON? (picture from Harvey Flood) How can a submerged circuit, both grounded & ungrounded conductors, not trip the breaker? How can you have all these energized wires in the water and not electrocute everyone around?
    The porch light could be fed thru a lighting circuit in the attic and down to the panel, which also isnt underwater at this point. Also, even if everything was underwater, older breakers with just a thermal trip could be in play. Even if it was powered from a receptacle that's underwater, the electricity tries to return to the source, which would be the grounded conductor on the other side of the receptacle.... not much current/voltage is going to 'swing out' from there to electrocute someone.

    Even if GFCI protected, pretty sure I've seen videos of people dropping hair dryers in tubs... for the most part, they will still run and not even trip the GFCI on the plug or branch circuit.
    Electricians do it until it Hertz!

  5. #5
    Join Date
    Dec 2007
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    Quote Originally Posted by RomexRocket1 View Post
    How is it that a house in the 3' of flood water still has a front porch light ON? (picture from Harvey Flood) How can a submerged circuit, both grounded & ungrounded conductors, not trip the breaker? How can you have all these energized wires in the water and not electrocute everyone around?
    You need under 8 ohms to get enough current to flow at 120 volts just to even start thinking about drawing enough current to overload a 15 amp overcurrent device. Water just isn't that conductive. There is shock hazards if you get near where the water contacts live parts though.

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