Are the MacBook Pro's properly grounded?

Discussion in 'MacBook Pro' started by sniffs, Mar 26, 2013.

  1. sniffs macrumors regular

    sniffs

    Joined:
    Jan 24, 2013
    #1
    Whenever my laptop is plugged in, if I very softly touch/rub the left side of the aluminum where the laptop plugs in, I can feel almost a slight abnormal vibration that makes my fingers tingle.

    It actually feels like the laptop isn't properly grounded and the aluminum is giving off some sort of electric noise? (not sounds)

    I can't explain it but I can only feel it when it's plugged in. If I press firmly I don't feel it at all, but if I ever so slightly touch it, I can definitely feel something's not right. Doesn't happen on the right side.

    Anyone have any ideas?
     
  2. chrise2 macrumors 6502

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    Sep 17, 2012
    #2
    2 prong charger = no ground. No ground = finger zap. Bzzzzttt...
     
  3. dukebound85 macrumors P6

    dukebound85

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    #3
    The two pronged charger just doesn't have a dedicated ground. Doesnt mean it is not grounded. It merely uses the neutral wire for grounding
     
  4. john500y2k macrumors member

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    Feb 28, 2013
    #4
    I know the exact sensation/feeling that you are on about. My dad's Macbook Air does the exact same thing (your description was uncanny when I read it). I borrowed it for around a week to see if I liked the whole Mac OS having never used it. I found that I could feel it most with movement, such was palm sliding across palm rest.

    At the time it was my only experience ever using a Mac product and thought it was a bit strange but had no comparison to know if it was normal or not.

    Since then I now have a rMBP which does not have this sensation and I can say that all the Mac's I have used now and tried in the Apple store do not have the same "plugged in buzz". So there is something different.

    I have tried telling my dad to pop into an apple store and see what they say but unfortunately he is yet to be motivated.

    Only thing I can think is have you tried a different power supply? I didn't have that option available to me at the time to test.

    TL;DR: My dad's one has the exact same feeling that you are talking about. I have since then tried several other macs and my own rMBP where none have this same feeling. He has yet to go to an apple store about it. Have you tried a different power supply as I wasn't able to try that out?
     
  5. sniffs thread starter macrumors regular

    sniffs

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    Jan 24, 2013
    #5
    I've not tried taking it into an Apple store or another supply yet, my MBP is 5 months old.. the best way I can describe it is that I'm feeling the electric harmonic vibrations.

    I'll have to bring it in and HOPE I can replicate it to the technician.
     
  6. Adomas macrumors newbie

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    Mar 4, 2013
    #6
    My previous 2010 mbp and current cMBP has this feeling, while I recognize it sometimes, it doesn't bother me.
     
  7. squintypanda macrumors newbie

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    Mar 19, 2013
    #7
    I have the same problem with my 2013 15' RMBP

    with the power plugged in, I can feel a slight vibration almost anywhere across the aluminum surface. This doesn't bother me that much, as I've had similar problems with previous laptops (Had an Asus previously and my iPhone would shock the crap out of my ear if I tried to talk on it while it was plugged into the computer :eek:)

    However, when my arm/wrist grazes the front edge while I'm typing, I sometimes get this shock/pinch sensation that isnt' very pleasant :(

    The problem goes away when I'm using the three prong extension or if the laptop is unplugged. However not all places I goto have a three prong outlet

    Not sure if all macbooks do this but I really don't want to return it since this one has a Samsung screen, lol
     
  8. Brian Y macrumors 68040

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    Oct 21, 2012
    #8
    Nope - it's not grounded at all. The ground on the MagSafe adapter is the big metal circular pin. Check the inside of the small plug - it's plastic - there's no ground contact.

    It's perfectly normal when using the short plug. Replacing it will not help.


    As above - totally normal.
     
  9. b0fh666 macrumors 6502a

    b0fh666

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    south
    #9
    not true, it is bivolt (110-240) and 240 has no 'neutral wire' for grounding, both are live.

    it is fully isolated from the mains tough, that is until it breaks :D
     
  10. justperry, Mar 27, 2013
    Last edited: Mar 27, 2013

    justperry macrumors 604

    justperry

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    #10
    I am an electrical engineer and comments like this should be removed because it is complete nonsense.

    The common wire is/should be Zero volts, In my country the Electricity provider will connect the common wire to the earth/grounding wire when it enters the meter, they to this to equalise it with the ground, the common wire is also connected at the power plant and or distribution stations.
    Only the live wire has a voltage in normal cases, yes, if you cut the common wire and touch the one coming from the load it will have the same voltage as the live wire, but this is then faulty.
    The 110/240 volts AC means Amplitude Current and what the live wire does is it goes +110V/240V positive against the common wire and the same negative.

    ------

    Now, for those having the issue the OP started this thread with, it is "normal" to feel this depending on how well the 0 Volts common wire is Zero, if your common wire is connected to the grounding as in my country you will feel nothing or very little.
    It also depends on if you wear shoes, bare feet and what surface you stand on,if it's bare feet on a tile floor you will feel it more, lift your feet from the ground if you are sitting and it's gone.

    NO need to bring it to Apple, it's not their fault, well sort of, if they make them of plastic the issue wouldn't be there, it's your wiring.
    You shouldn't be afraid though, it's a minor annoyance, nothing more and it won't kill you.
     
  11. squintypanda macrumors newbie

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    Mar 19, 2013
    #11
    Thanks for clearing things up! The thing I'm worried about the most though is will this harm my macbook in anyway?

    I'm concerned because with my old Asus, it sure feels like it did. After 2 years, USB ports would randomly shut down at times and only work again if I reboot. Also certain keys become unresponsive after prolonged use. Not sure if it was the extra voltage that eventually "fried" my computer or if it was just bad luck.

     
  12. justperry macrumors 604

    justperry

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    #12
    No it won't, I am typing this on an old 8 year old Powerbook and it still works.

    I can get more technical but just ignore it, the problem lies with the wiring is some houses or countries, the Common wire should be grounded, if this is done well you almost feel nothing.

    Oh, about grounding Macs, all Apple laptops are not grounded.
     
  13. Stetrain macrumors 68040

    Joined:
    Feb 6, 2009
    #13
    Isn't AC generally 'Alternating Current'?

    There are 240v circuits in which the two leads are both 120v AC potential to common, but they are out of phase so that the voltage between them is 240. In that case you need a third ground lead to have a true ground. This is how the larger 240v dryer outlets work in the US.

    I think that it most cases though you are correct.
     
  14. b0fh666 macrumors 6502a

    b0fh666

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    #14
    are you sure you are an electrical engineer? your country seems to have odd home power, but maybe it is the center of the universe or something... hah

    here we get 240V by means of two 127V out of phase, not a single 240AC and a neutral, that would be downright dangerous to have at home.

    ass
     
  15. lpmusix macrumors newbie

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    Sep 17, 2006
    #15
    I'll agree I doubt he's an EE if he got Alternating Current wrong (http://en.wikipedia.org/wiki/Alternating_Current), but having 240VAC isn't really more dangerous than 120VAC, both'll kill you if you go grabbing the live wires just the same. It's not voltage that kills, it's current.
     
  16. b0fh666 macrumors 6502a

    b0fh666

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    #16
    yeah, but most shocks are from grabbing one live while barefoot (kids sticking stuff into the outlet), in this case a 240V live is a lot more danger than a 127.

    if you touch both, you are in for a world of hurt no matter what :D ... more than once I touched the B+ and chassis (with the same hand, thankfully) of a tube amplifier, that's ˜480VDC... ouch!
     
  17. justperry, Mar 27, 2013
    Last edited: Mar 27, 2013

    justperry macrumors 604

    justperry

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    #17
    Bold first, I made a mistake in the word, don't know why, probably a brain fart, it is Alternating Current.
    The US seems to be a strange country with standards, many things are different and it's the same with power, almost everywhere it's "real" AC 240 Volt.
    The next picture shows the Common has no voltage on it.
    You are talking about 2 phase power here and even those are + and - (Positive/negative) against the common wire.

    [​IMG]


    Bold, yes I am but I made a little mistake, must be language.
    And you are again (partly) wrong, I don't live in the US so I won't say anything about the first part but the second is certainly true, one phase and a common wire, that is normal in the world, not your non standards!

    Yes, but in relation to the voltage and partially frequency, I say frequency because humans have a 50 Hz internal Freq., now this means that if you grab a live wire your muscle will react in a way that your hand closes so you can't release the wire, if the frequency was much different you still had/have a chance.
     
  18. Nameci macrumors 68000

    Nameci

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    The Philippines...
    #18
    In the US, one line is "hot" and the other is supposed to be neutral which is zero. But neutral is not always zero. It can have a potential as high as 9 volts when measured against earth ground. If the OP happens to have a two prong plugged then there is no earth ground. Earth ground is connected thru the body of the device and the neutral to ground voltage is being drained from the device thru your body to the earth. That is what you feel a tingle. If your house electricity happens to have a three wire connection, L, N and PE(Earth Ground) then the device will be properly grounded by using a 3 prong plug. I always use the extension cable, it has 3-prong plug, while duck head plug only has two.

    Remove it from the AC outlet and you will not feel the tingle.
     
  19. b0fh666 macrumors 6502a

    b0fh666

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    south
    #19
    here in .br it is phase+phase+neutral (which is indeed grounded, usually at the meter itself, but norm dictates that you need the ground at all outlets too). That way you can do:

    phase+neutral -> 127
    phase+phase -> 220

    apple's power brick works fine with either, ungrounded.

    now I'm curious, which country(es) run 240+neutral for home power?

    cheers
     
  20. justperry macrumors 604

    justperry

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    #20
    As I said, most of the rest of the world, I know Europe and Asia/Australia NZ do so.
    I have been to several south american and all central American countries and I think all of them had 240 Volts 1 Phase power supply.


    All Apple devices which have the adapter outside of the device do not have grounding, even if you can swap the cable with a grounded cable it will still not ground these devices, like all Laptops, you can not ground them this way, if you want to ground it you need to get a wire from the ground to the body of the MacBooks.
     
  21. Andydigital macrumors regular

    Andydigital

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    Feb 9, 2013
    #21
    Its DC that causes your muscles to contract and grip a live wire, not AC. AC will not cause muscle to tense but rather vibrate, so no contraction. That's the whole reason the UK and Europe use 220 to 240VAC in the first place because its safer.
     
  22. justperry macrumors 604

    justperry

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    #22
    Any sparky will tell you otherwise.


    You can look here:

    Emergent Care of Lightning and Electrical Injuries


    It has been customary to use the terms "entry' and "exit" to describe electrical injuries. Particularly with AC, this is clearly a misnomer and the terms should correctly he "source" and "ground." The hand is the most common site of contact as it grasps a tool coming into contact with an electric source. Although all the muscles of the arm may be tetanically innervated by a shock, the flexors of the hand and forearm are much stronger than the extensors so that the hand grips the source of the current. At currents above the let-go threshold (6 to 9 mA), this can result in the person's being unable to release the current source voluntarily, prolonging the duration of exposure.
     
  23. Andydigital macrumors regular

    Andydigital

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    Feb 9, 2013
    #23
    You are correct, I can't believe I mixed that up (my dad will go nuts if I tell him he's been a sparky all his life) and I find it even stranger that Europe would use a system that is inherently more dangerous. I think I remember having this conversation with a lecturer decades ago, lol.
     
  24. justperry macrumors 604

    justperry

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    #24
    The problem was that DC couldn't be transported over long distances before, but now with new technology it is possible, if this was possible when electricity networks were introduced AC would not have a place in the world as it is today.
    Most devices work on DC nowadays, almost all electronics if not all do, it's things like motors which mostly use AC although DC motors are as good but converting high voltage AC to DC is just not viable because of too many loses.
     
  25. F1 Fan macrumors regular

    F1 Fan

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    UK
    #25
    I seem to remember my teacher telling me that AC and DC were competing for win and despite DC being the better (safer) system, the guy in the AC corner was better at marketing. Isn't it always the way?!


    EDIT:

    So AC did have a real world advantage then? Every day's a school day!
     

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