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In my house we have 2 outlet power sockets (no earth) and whenever I charge my laptop I would get electric shock from the laptop when I am touching ground like if I hold laptop on my lap and touch the wall or if my foot touches the floor. At the very least I feel vibrations in the laptop. Same for CPU body, mobile (if has some metal layer on it) ..

I have solved this problem for my room only by grounding my extension where I plug charger to garden outside my room. Basically my extention sockets have 3 outlets, I plugged one end of a cooper cable in one of the grounding outlet and the other in the garden soil. This solved the problem for my room, I do'nt get any vibration or current shock from my laptop in my room.

The problem persists though in the rest of sockets in our house like if I charge my htc desire mobile which has a bit of metal on it, I would be shocked if I happen to touch it bare footed while it is charging..

So this situation is persistent now and not something that happens rarely or occasionally.

I have tested the 2 outlets of the power socket

  • I have checked the neutral/cold line shows no current (using the current testing screw driver), so assuming the potential is 0 there,
  • hot line indicated current as expected
  • The wire that I used in my room to ground one of the sockets, shows a bit of current

So given my situation that I have 2 pin power socks and house is not wired with grounding/earthing wire, how can I find the cause and resolve it

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migrated from electronics.stackexchange.com Sep 10 '12 at 19:22

This question came from our site for electronics and electrical engineering professionals, students, and enthusiasts.

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Short answer: If you replace your circuit breaker with a GFCI type, or replace your outlet with a GFCI outlet, it will detect that current from the hot line is not returning through the neutral and shut down the circuit before you electrocute yourself. As to how to fix this so that not only do you stay alive, but also be able to use the outlet for something useful, I think we need more information. It's not obvious to me from what you've said where the real problem is. Do you ever get shocked by lamps or other appliances in your house? –  The Photon Sep 10 '12 at 19:21
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"get an electric shock from the laptop when I am touching ground" - please expand on what you mean by "touching ground"? Are you touching the ground beneath your feet? Or are you touching the ground plug on the laptop power cord? –  The Evil Greebo Sep 10 '12 at 19:42
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Most computer power bricks don't have a ground so not sure that would help you in your case. FWIW, the old Apple TiBooks had this issue where you could feel current with your palms on the computer and bare feet on concrete or earth. I solved it by always having my feet on a rubber matt. –  DA01 Sep 10 '12 at 20:20
    
photon's is not correct that is just a placebo method. da01 plenty of the larger laptops are 3 prong. 130w power supplies tend to have 3 prongs. original post is unclear are there 2 prongs at the wall or 3? if 3 who ever wired your house if a professional should repair the miss wiring though it may have been done before code required such. you need 3 wires from the pannel to the 3 prong outlets even with 2 prongs you should not be getting shocked there may be a large number of issues with the system. –  Kendrick Sep 11 '12 at 3:23
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Ground(earth) is a safety device, and should never have current on it (under normal circumstances). If a device is shocking you, adding a ground is not the way to solve the problem. Either the device is faulty (contains a ground fault, which energizes the frame/case), or the building wiring is faulty. Either way the solution is not adding a ground, it is to locate and fix the fault. –  Tester101 Sep 11 '12 at 12:13
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2 Answers 2

That you're using a two-prong outlet is a red herring. Your laptop's charger is not a three-prong device, right? If you plugged it into a properly wired and grounded three-prong outlet, the situation would be the same. The third prong actually has to be used to have any benefit at all.

This business of being shocked by the laptop is a consequence of its bad design. Internally it has a "ground-like" network that we might call "common". Although it has no real ground, it has a connection between its "common" and the chassis. (A grounded chassis is a good idea---if there is a real ground.)

This common is "floating" with respect to some actual ground (meaning that it's at a different voltage), and so if you get yourself in between this common and a ground, electricity wants to go through you.

According to Dell, the shocks are harmless: http://www.pcworld.com/article/141516/article.html :)

Also: your screwdriver is not a current tester. It detects the presence of voltage. It works by making you part of a circuit. (Recall, we know from Dell above that using people as resistors and capacitors is completely harmless!) If you touch something that is above or below ground potential, then you complete a circuit. A tiny current flows through test light, you, to the ground, enough to light the test light.

According to your test, there isn't enough voltage across your body when you touch neutral. So your room is at the same potential. The ground wire from the garden is at a different potential, so it lights up the screwdriver. This does not prove or disprove whether that line is a proper ground. A proper electrical ground is not only a voltage reference level, but a sink that can take large amounts of current (not only the tiny current that lights up the screwdriver). So the wire has to be thick gauge. And you have to have a good coupling to the soil (like a long metal rod that is deeply pounded into the soil). The soil must not be very resistive, either.

I would contact your city for advice. Other houses in the neighborhood surely have the same kind of old wiring. Running ad hoc wires into garden soil is probably not the way.

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I'd pick up one of these at the hardware store:

enter image description here

If you're not in North America, I'm sure there's a local equivalent.
Based on the LED's that light up, you can tell if the circuit is wired correctly. The only thing it can't detect is a ground/neutral swap. But it can detect a missing ground.

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He mentioned a lack of earth (ground), so I'm not sure this tester will identify much in that situation, other than "no ground". –  BMitch Sep 10 '12 at 20:47
    
@Chris Cudmore There is no earth wired in the house all power sockets in the wall have 2 holes .. –  Ahmed Sep 11 '12 at 9:03
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3-prong tester won't be much help with 2-prong receptacles. :) –  Jeremy W. Sherman Sep 14 '12 at 0:04
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