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Topic Review (Newest First)

  • 08-17-2012, 09:27 PM
    WhoIsThat?
    Quote Originally Posted by timebuilder View Post
    CAREFULLY..........
    Yeah.
    There was a guy in EC&M who got 120v and seemed OK but later developed problems. His expert witness said that the guy might have gotten 500 mA through his body.
    This is 120v/0.5A = 240 ohms. Almost nobody almost none of the time who is not soaking wet has a resistance this low but I guess it can happen. 3000 ohms and up is more reasonable.
  • 08-17-2012, 08:45 PM
    timebuilder
    Quote Originally Posted by Joehvac25 View Post
    I had one probe under a wire nut then the other one dropped to the floor and my meter started beeping. Maybe I will do some experimenting.
    CAREFULLY..........
  • 08-17-2012, 10:33 AM
    Joehvac25
    Quote Originally Posted by WhoIsThat? View Post
    Concrete is a semiconductor and wet concrete is a pretty good conductor. See if you can light a 7-1/2W bulb that's hooked up between the hot line and the floor. If that works, try a 100W bulb.

    Since you're not dead I guess the current flow, 120v through concrete resistance through skin resistance through body resistance and back through skin resistance was less than 20 mA or so. 10 mA is painful and 1 mA is a tingle.
    I had one probe under a wire nut then the other one dropped to the floor and my meter started beeping. Maybe I will do some experimenting.
  • 08-17-2012, 09:01 AM
    WhoIsThat?
    Concrete is a semiconductor and wet concrete is a pretty good conductor. See if you can light a 7-1/2W bulb that's hooked up between the hot line and the floor. If that works, try a 100W bulb.

    Since you're not dead I guess the current flow, 120v through concrete resistance through skin resistance through body resistance and back through skin resistance was less than 20 mA or so. 10 mA is painful and 1 mA is a tingle.
  • 08-17-2012, 08:26 AM
    Snapperhead
    concrete also loves humidity and acts like a sponge
  • 08-14-2012, 07:56 PM
    Joehvac25
    Quote Originally Posted by timebuilder View Post
    It "should be," but in his case, it is not. HE has a high impedance path between his concrete and the neutral bar in his service panel, probably via the ground under the concrete and out to his grounding electrode, and back to the neutral bar.
    I'm wondering if the fact that the floor was wet (100 year old house leaky basement) it helped the process?
  • 08-14-2012, 07:44 PM
    timebuilder
    Quote Originally Posted by second opinion View Post
    That should be low impedance.
    It "should be," but in his case, it is not. HE has a high impedance path between his concrete and the neutral bar in his service panel, probably via the ground under the concrete and out to his grounding electrode, and back to the neutral bar.
  • 08-14-2012, 05:32 PM
    second opinion
    Quote Originally Posted by timebuilder View Post
    Today, system grounds are bonded to piping, structural steel, and rebar embedded in concrete. You are reading 120v because those bonds are connected to the system neutral at the panel. In this case, your concrete is completing a high impedance circuit to your ground rod, and to the neutral at the panel.
    That should be low impedance.
  • 08-14-2012, 04:37 PM
    Joehvac25
    Thanks timebuilder it makes sense now, at the time I didnt think of it like that, I feel dumb now for even mentioning it as I do some electrical work with our sparky sinking ground rods and such.
  • 08-14-2012, 03:55 PM
    dlove
    I guess that's when you know it's time to fix the washer, when all you have left is underwear lol.

    LMFAO...so true so true.....
  • 08-14-2012, 02:26 PM
    timebuilder
    Today, system grounds are bonded to piping, structural steel, and rebar embedded in concrete. You are reading 120v because those bonds are connected to the system neutral at the panel. In this case, your concrete is completing a high impedance circuit to your ground rod, and to the neutral at the panel.
  • 08-14-2012, 11:38 AM
    Joehvac25
    Quote Originally Posted by ar_hvac_man View Post
    lol i learned the hard way, working on my washing machine in nothing but boxers
    I guess that's when you know it's time to fix the washer, when all you have left is underwear lol.
  • 08-14-2012, 11:34 AM
    ar_hvac_man
    lol i learned the hard way, working on my washing machine in nothing but boxers
  • 08-14-2012, 11:32 AM
    Joehvac25
    Quote Originally Posted by ar_hvac_man View Post
    Hot to ground = 120v. Say your standing on concrete with rubber soled shoes. You can grab that hot wire and it wont shock you. Take your shoe off and grab that hot wire. zingg
    Ya I get it just surprised me, didn't think I would get 120 to the floor.
  • 08-14-2012, 11:22 AM
    ar_hvac_man
    Hot to ground = 120v. Say your standing on concrete with rubber soled shoes. You can grab that hot wire and it wont shock you. Take your shoe off and grab that hot wire. zingg
  • 08-14-2012, 11:20 AM
    Joehvac25

    110v between hot line and concrete floor

    I was working on a oil furnace today and was testing the primary control, I has one probe of my meter on th line voltage and the other probe was touching the floor and meter started beeping. I look and it says 115 or whatever so I keep trying and every time the same thing. I guess it's possible but just thought it was wierd.

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