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Experiment with grounding and EMFs

  1. Dec 4, 2012 #1

    I'd like to do a simple experiment to see how grounding influences the EMF generated by an appliance. I'm a novice at these sorts of things though, and I want to be sure that there aren't any safety concerns which I'm not aware of. In order to do my experiment, I would modify a 3 pronged power cord by bending aside the hot plug and taping it completely over with electrical tape, so that only the neutral and ground plugs connect. I would then plug an appliance in to a standard house outlet with this cord and measure how its magnetic field differs from when it is plugged in normally. Would there be any potentially serious hazards in doing this? Also, would it ever be possible for electrical current to travel up through the neutral and/or ground slots of the outlet and into the appliance rather than flowing only in the other direction? Would uncommon events like a power surge or lightning strike have any effect?

    Thanks for your replies,
  2. jcsd
  3. Dec 4, 2012 #2


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    Staff: Mentor

    Welcome to the PF.

    As long as your home is wired to code (I'm assuming you are in the US), there should not be any safety issues with disconnecting the Hot lead. Just be sure to disconnect the Hot lead and not the Neutral...!

    The results will show that there is no electrification of the appliance if Hot is disconnected. How are you planning on measuring any magnetic fields? What is your overall goal in doing this?
  4. Dec 4, 2012 #3
    I am not an electrician, this is my understanding:

    If your house electricity is wired correctly, there should be no current in and out of the appliance if you disconnect the hot wire. The ground is usually a long rod pounded into the ground soil as ground safety. The neutral is the return wire of a 3 phase hot wire. It is supposed to be grounded to earth like the ground wire in the power station. Only two hot wire is connected into the house.....say call them red and black wire. Each is 110V reference to the neutral wire. But it is 220V across the red and black wire. So in your house, the 220V plug is just the red and black wire, your 110V is either red with neutral ( white) or black with neutral.

    So if you cut the hot wire, you have no power......theoretically!!!! BUT, BUT, I have seen houses with wrong wiring, they can accidentally switch the neutral and hot wire around and if you just cut the wire you "think" is the hot wire, you still have the power connected and that is deadly dangerous.

    So you need to be careful, use a safety check plug ( one that has LED or lights that show what is safe and what's not) to test the plug before you do this. But I still don't see the point of you doing this as there is no power if everything is correct.
  5. Dec 4, 2012 #4
    Great. Thanks for the info guys. I'll be measuring the EMF with a meter, and I forgot to mention that I'm planning to do this with a laptop running on battery power. It would indeed be pointless to try it with something that has no battery, though admittedly my knowledge of physics isn't thorough enough to know if there is a point even with a device running on battery power. My rational is simply curiosity. Gaining an understanding of the physical world and all that.
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