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Shock to an infant when pulling power cord out of a wall socket

  1. Aug 20, 2016 #1
    My son occasionally pulls plugs from powerpoints. We tried to get a powerpoint cover but the strong tape here in Japan is weak and it fell off easily. I was just wondering how much electric shock he might get from pulling out the cord when the device (a fan) is operating. Its a two prong connector in Japan with 100 V. There is No Residual Current Device but there are circuit breakers. This is the ground floor and it is raised above the ground. Estimate the electric shock he might get if we stop him 1 second too late? He is 8 kilos.
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  3. Aug 20, 2016 #2


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    Estimates are meaningless, except to say what you already know---100VAC can well be fatal.

    Don't bank on catching him in time, he'll soon learn to wait until your attention is focussed somewhere else. Until they learn not to meddle, you must physically separate toddlers from danger.

    Some plugs have a black insulating coating applied over half of each pin, as a small safety measure against accidental shock should fingers contact the plug when it is halfway out of its socket. I don't know whether these are available in 100V countries, but it would afford a small protection if you can get one fitted to you power cord/s.
  4. Aug 20, 2016 #3

    Fervent Freyja

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    This could be fatal. At under a year old, he is likely to be barefoot and wet.

    We will assume his skin resistance to be 1,000 Ω if he touches a 100 V plug-in with cute, slobbery hands. So, the electrical current could be up 100 mA, which can be fatal. Physiological effects for 100-300 mA are Ventricular fibrillation, fatal if continued. Respiratory function continues.

    My advice is to go ahead and place plug-in protectors in all unoccupied outlets. If he's been eyeing a certain outlet, then you need to either order a box cover or make one yourself (a box with a small hole attached to the wall will work, as long as it is secure and sturdy). It's only a matter time if he's already interested.

    In the case that he is shocked: Although pulling the breaker is a good idea, the quickest option will be to use a non-conducting object like a toy or pillow within reach to break the connection.

    Edit: This is per second. The heart can receive up 60 electrical pulses per second during a shock; after one cardiac cycle, the threshold for ventricular fibrillation can be reached. That's all it could take!
    Last edited: Aug 20, 2016
  5. Aug 23, 2016 #4
    I would strongly recommend installing a Residual Current Device designed to protect life.
  6. Aug 27, 2016 #5


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    Teach him not to do it! If he is too young to learn it's your responsibility to physically prevent him.
  7. Sep 6, 2016 #6


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    At the conclusion of this thread, there are 2 points that should be emphasised:
    (i) circuit breakers should never be thought of as protection against shock, their purpose is basically to protect devices and wiring and try to prevent fire due to sparking or overheated wires, and
    (ii) in the specific scenario of meddling with a 2-pin power outlet and plug, a Residual Current Device adds no protection at all, though it is still recommended for all homes for the protection it can give in plenty of other hazardous situations that can arise.
  8. Sep 6, 2016 #7
    In the US there are new residential codes for exactly this. Now, homes will be required to have arc fault breakers on any circuit that provides power to a receptacle. Arc fault breakers are designed specifically to prevent accidental electrocution or fires. In addition, receptacles must be tamper resistant to prevent children from sticking metal objects into unoccupied receptacles.

    I realize that you are in Japan but you may have equivalents in your country.
  9. Sep 8, 2016 #8
    Regarding item (ii), I agree that a RCD will not protect against a situation where the person places themselves between, say, Line and Neutral. However, these RCDs are so sensitive that the slightest imbalance whilst the person is tampering may trip the circuit.
    In the UK the standard plug has an Earth pin which is longer than the two others and which opens a safety shutter when inserted, so it is essentially shock proof. But countries differ, and I have seen in Japan an example where an exercise machine had a Ground (Earth) connection made with a separate screw terminal.
  10. Sep 8, 2016 #9


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    Which is why I felt it needs to be pointed out it offers no peace of mind in the specific situation described: in a 2-pin plug/socket where tampering will cause no imbalance, an RCD will not trip. Users should not put blind faith in these devices, they can't and don't cover all hazardous scenarios.
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