Safety Issue.

Discussion in 'Feedback and Suggestions' started by Unregistered, Nov 8, 2007.

  1. Unregistered

    Thread Starter Guest

    your electrical safety section has a bit of a loophole I'd like to clear up...

    It states that when you touch an energized circuit that isn't grounded, you don't get electrocuted. This most certainly is not true, especially if you ask anyone thats been struck by lightning. The ground is what it is only because of its ability to absorb electricity, and in doing so, dissipate it. In the diagram involving the tree touching the power line accidentally and electrocuting the unfortunate stick figure, the tree would burn before any person(or any path) touched it because of its path to well as any person, tree or not.

    When you touch something energized without insulation, you create a path to ground, which instantly absorbs electricity. When you get struck by lightning, you're not touching a circuit thats grounded, you become the circuit, as well as its path to ground. If you wonder why batteries don't shock you, then use Ohm's law to figure out why.

    My career evolves around electrical safety. I wear rubber gloves insulated to 36000V everyday, and I know that if you touch a wire with that kind of voltage while providing a path to ground, you will die. If the power line is given a good path to ground, there will be an flash and explosion very much like a lightning bolt, and in the case of contact with concrete poles, concrete will actually explode off the pole. I have heard many a story about people losing limbs from the burns caused by slight contact with power lines so don't forget: there may not be enough current to stop your heart, but that doesn't mean there isn't enough current for you to lose your arm.

    Other than this mis-step in safety the site is great, and I'll remember it when i go to tradeschool again.

    - Powerline Technician
  2. recca02

    Senior Member

    Apr 2, 2007
    which cases do you exactly feel were conceived wrong is there a specific case you are pointing to or all of them?
    some of the members here might want to discus those here in detail.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    This is a common misconception. Ground does not "absorb" electricity, nor does electricity "seek to return to ground."

    Current can and does flow via ground back to the source. The text references an open circuit without return path, and is quite correct. Every bird and squirrel on the power-line outside my window says so.:D For further information do an internet search on "Faraday cage."
  4. Unregistered

    Thread Starter Guest

    I suppose its my mistake then...I see what you are saying and I've given it some thought. The return path we use (the neutral) is grounded at several intervals where need requires, and I suppose you're saying that since this neutral is grounded, and also I am as well, I create an alternate path...

    Another question then. What about lightning? What neutral carries its return current. Also what makes the "ground" so conductive to provide such an explosive path back to the neutral?

    What about step potential, and the ripple effect it makes. When the voltage dissipates across the ground and you're still electrocuted from simply walking with your feet apart.

    Where does this return go then? Certainly not to some gigantic battery for return feeds...does it not go to ground at the end of the line?

    I also found this on Wiki, about Faraday cages
    "The metal layers are connected to earth ground to dissipate any electric currents generated from the external electromagnetic fields, and thus block a large amount of the electromagnetic interference."

    P.S. Your birds and squirrels make me lots of money and have little to say when theres 3 feet of flames jumping off of them because they bridged an insulator with a grounded pole.

    PPS. I'm not trying to argue or anything. If you have answers, I'm desperately seeking them
  5. Dcrunkilton

    E-book Co-ordinator

    Jul 31, 2004
    begin quote
    Another question then. What about lightning? What neutral carries its return current. Also what makes the "ground" so conductive to provide such an explosive path back to the neutral?
    end quote

    Lighting is a result of a difference in potential generated between a cloud and ground. You can look at the Earth as being the nuetral. Rainfall, wind, and other atmospheric phenomenon can seperate positive from negative charge on a massive scale. This is something about scuffing your shoes across a synthetic carpet, building up a charge. This cloud to ground path builds up a charge over a period of time. The cloud is like a giant battery. One terminal is the cloud, the other is the Earth. Once enough potential difference (voltage) builds up, air ionizes (becomes almost as conductive as metal), creating a conductive path from cloud to ground dischaging the potential difference.

    begin quote
    What about step potential, and the ripple effect it makes. When the voltage dissipates across the ground and you're still electrocuted from simply walking with your feet apart.
    end quote

    The Earth (ground) is not nearly as conductive as metal, or the ionized air lightinig bolt. There is a considerable voltage drop across the few Ohms of resistance. A 1-killo-ampere lightning discharge traveling through a 1-ohm ground is 1000 V by Ohm's law E=IR 1000=1000(1). The ground is likely to have an even higher resistance than 1 Ohm.
  6. Unregistered

    Thread Starter Guest

    I understand that thanks, but my question was asked because if the ground doesn't act as a neutral, then lightning wouldn't exist. Since his argument was that the ground doesn't act in that way, and there most certainly is lightning, I was wondering how that could be.

    I appreciate the response regardless

    Another argument that proves the workings of the ground is in high voltage transmission lines, that don't use a neutral. They rely on an intricate grounding grid at transformer stations. This also applies to "Delta" services that don't provide a neutral, as apposed to "Y" services that do.

    My argument is simple. When you touch a live circuit that has NO REFERENCE TO GROUND, like say, a car which uses the frame as a ground, you will get a jolt. This is particularly important when working on rural distribution lines where the neutral might have a reference to ground once every couple of kilometers, and where you'd normally only get a tiny zap in the city, you could easily die in the country. Just because a circuit has no grounded neutral, doesn't mean it won't shock you, and it certainly doesn't mean the "live" side of the circuit won't either.
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    Lightning does not occur because of the planet acting like a branch circuit, but rather because of the planet acting like a capacitor. Whether lighting strikes from the sky to the ground or from the ground to the sky is entirely a matter of perspective. The dielectric (air) breaks down and the capacitor discharges across this path. This discharge is the return to the source - the capacitor charged up over the course of the storm developing.

    We could as easily claim the sky is the neutral.

    Step potential, like lightning, is just a part of a bigger circuit. We have to look at the entire circuit. (The very word "circuit" implies this.)

    The term "no reference to ground" is in error. If you or I are at a different potential from what we touch, then current will indeed flow. If we are not at a different potential and if we also provide no path of return to source, then we will not conduct. This is why your buddies in the helicopters can hang from HV lines after equalizing the potential. Your battery shocks you because there IS a difference of potential between the terminal and whatever else you touch. This difference of potential causes current to move through your body.

    Again; the ground does not "absorb" electricity. Nothing "absorbs" electricity. Grounding of the neutral is to provide a path of conduction alternative to me or thee. Clearly its not a good enough path in the rural zones you cite.

    The text makes no such claim. No such claim is made in this thread either. The text only claims - and this is an accurate claim - that getting shocked requires a difference in potential across the body.

    Again, a difference of potential across the body. When the birds and squirrels are simply hanging from the line with no difference of potential, there is no current flowing through them.

    Your input is valuable. I'd like to invite you to register and join in officially. A person of your training and experience would be a most welcome addition to our forum!