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Power from the outlet for an electrical experiment

  1. Jan 8, 2005 #1
    I want to use power from the outlet for an electrical experiment. I will do this by using an adapter from an old appliance which steps down the volts and amps. The adapter takes regular American outlet power (120v, 60hz) and outputs 4.5 volts and .6A.

    Now, is this dangerous? If so, how dangerous? I heard on Mythbusters that only a couple hundred mili amps isnt too dangerous, so I'm wondering if this is.

    Thanks. :smile:

    EDIT: I'm also thinking about using higher power. Is 12volts and 1.0A still safe? How high can i go?! :smile:
    Last edited: Jan 8, 2005
  2. jcsd
  3. Jan 8, 2005 #2
    .5 Amp at 120 Volts will kill you if can not unattach from it. Power=I(E).
    .5(120)=6o Watts depending on PF. In a purely resistive circuit,there is none.

    Are you rectifying the current? Is it AC or DC current?
    12(1)=12 Watts. I would be cautious and not clamp the leads to my body.

    Hope this helps. To be safe, have someone present or attach to A GFCI outlet or breaker.
  4. Jan 8, 2005 #3


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    Research ohms law. Unless you are implanting electrode inside your body, the power source you are using is safe.
  5. Jan 8, 2005 #4


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    how dangerous is electricity? 1 amp can stop your heart.

    i wont touch or complete the circuit with my body if i was you no matter what the charge is
  6. Jan 8, 2005 #5

    Andrew Mason

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    You are right that that amps are what kill you. But to put one amp through your heart you need more than 4.5 volts. Ohms law gives the relationship between volts and current.

    A transformer steps up/down voltage, not current. Current depends on the internal resisitance of the transformer windings and the load placed on the output.

  7. Jan 8, 2005 #6
    4.5 Volts @ .6 of an Ampere = 2.75 Watts. I have known that small amount of power to
    kill anyone. My nightlight is only 4 Watts. If that was implanted into a living brain, it would probably cause some damage, but I would not want to try that on myself. Although I did see a girl on tv drill a hole into her head with a common 120 Volt 3/8" drill motor. She was releiving excess blood pressure. Migraines I think.
  8. Jan 9, 2005 #7
    ECT devices exceed 1amp to treat patients with only a few major side affects.

  9. Jan 9, 2005 #8


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    Freep2, you just aren't getting it. A 12 volt car battery is only 12 volts but has a capacity of many hundred amps. Grab a terminal with each hand and it won't do a thing to you. BUT, it can deliver several thousand watts with ease to the right load. Your body is NOT the correct load to sink this kind of power at 12 volts. As I said, unless you implant electrodes in your body, its resistance is too high to pass any amount of current that will hurt you from a 4.5 volt source. Again, study ohms law.
  10. Jan 9, 2005 #9
    Thanks, that's what I thought. So I assume that 12v at 1.0A is also safe?

    BTW, does anyone know the minimum voltage required for current to pass through a person in normal circumstances?

    It's not like I'm doing anything really dangerous with it, Just a simple electrical circuit (and mabye some electrolysis hehe), so I doubt its a problem. I've been zapped by 120v with 20amps possible current kind of wet sitting on the bare ground so this seems light to me heh.

    Thanks :)
  11. Jan 9, 2005 #10


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    Jake if you look at ohm's law, there is no minimum voltage. If there is a potential difference (measured in voltage) then there will be current flowing along the conduction path. It might only be one billionth of a amp and imperceptable and difficult to measure but could still be there.

    The skin could be dry or have sweat on it or have a cut - all would influence the results.

    For lethality, other factors influence this also including timing (luck?) because it needs to interupt the heart at the correct time in its cycle.

    But generally speaking, 40V to 50VDC is the threshold to feel the voltage. Because AC is measured in RMS typcially the number is lower by roughly 30%. Not too far above this level the unfortunate application across the chest could cross the next threshold of lethality.

    You and many others may have been zapped at one point or another by high volts but the anecdotes do not provide evidence of lethality but typically more or less luck that the current didn't find a path that could prove otherwise.

    Think of a pacemaker the size of two half dollar coins stacked up and this can keep a heart beating properly or defliberate when needed and do this for years and you get an idea of how little it takes to keep things running internally. Once the threshold is passed to start flowing enough to be perceptible on the outside, the current can make its way inside quickly and it doesn't take much. Good job on asking the question in the first place, always better to be safe!

    For your original question, as long as you're only using the outputs of the adapter and its a UL listed device well away from any source of water you should be 100% safe with 4.5V and .6A.

  12. Jan 9, 2005 #11
    Thanks :smile:

    Err, I wrote in my original post that I heard "a couple hundred mili-amps isnt too dangerous" when it should be "a couple hundred mili-amps can kill someone" but I can't edit it?

    Anyway so it seems low voltages won't be a problem, as long as your very carefull :smile:
  13. Jan 9, 2005 #12


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    Cliif_J is right. The automotive industry, for example, has decided that anything less than 45V is totally safe for human exposure.

    The current rating on your transformer is a capability rating. The transformer is capable of delivering one ampere to the right load, but cannot deliver more without sustaining damage. It does not always deliver one ampere. Obviously, if it's not connected to anything, the resistance between its terminals is essentially infinite, and it delivers no current at all.

    - Warren
  14. Jan 9, 2005 #13
    Power in Direct Current. Lightning Bolt Power?

    Cloud to earth potential = 3(10^6) Volts (necessary for discharge). Is a typical bolt in the neighborhood of 5(10^3) Amperes? :confused:
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