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Macbook Pro Earthing

774 Views 12 Replies Latest reply: Feb 5, 2013 4:55 PM by medicinemanKE RSS
medicinemanKE Level 1 Level 1 (0 points)
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Feb 5, 2013 6:45 AM

I have recently purchased earthing products (grounding)....see http://www.earthing.com/ for more info.

 

My question is this - If my MacBook is connected to power with the three prong plug, and my hands are resting on the case while typing, am I grounded? 

 

In other words, is the case connected to the ground wire of the power cord?

 

Thanks

MacBook Pro, OS X Mountain Lion (10.8.2)
  • dominic23 Level 6 Level 6 (18,520 points)
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    Feb 5, 2013 9:16 AM (in response to medicinemanKE)

    If the wall socket is properly grounded, the computer is grounded by using a three prong plug.

  • Grant Bennet-Alder Level 8 Level 8 (48,135 points)
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    Feb 5, 2013 9:55 AM (in response to medicinemanKE)

    The DC side of the MagSafe power adapter cable has only two wires in it. One is wrapped around the other as a braid. There is no independent Earth/Ground connection all the way through to the chassis.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • Grant Bennet-Alder Level 8 Level 8 (48,135 points)
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    Feb 5, 2013 10:31 AM (in response to medicinemanKE)

    The DC side of the power adapter produces about 16.5 Volts DC.

     

    Underwriters Labs (UL) requires that you not be able to access anything over 35 Volts AC or DC with your bare fingers.

     

    The talk about "grounding the chassis of Appliances" comes from Appliances that are using 110 Volts tot 220 Volts internally.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • Csound1 Level 7 Level 7 (32,385 points)
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    Feb 5, 2013 10:45 AM (in response to Grant Bennet-Alder)

    Grant Bennet-Alder wrote:

     

    The DC side of the MagSafe power adapter cable has only two wires in it. One is wrapped around the other as a braid. There is no independent Earth/Ground connection all the way through to the chassis.

    That is incorrect, if you are using an Apple 3 pin connector on the magsafe the ground is connected via the metal mushroomy looking thing at the connection to the Magsafe. Search back, I posted photographs of the connection a few months ago.

     

    You can also connect one side of a voltmeter to ground and the other to the mushroomy looking thing (or the MBP casing)  and check that way. It is grounded if using a 3 pin AC connector (an Apple one)

  • Grant Bennet-Alder Level 8 Level 8 (48,135 points)
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    Feb 5, 2013 10:54 AM (in response to Csound1)

    Csound-

     

    Thanks for chiming in.

     

    It is entirely possible that one of the two DC wires to the computer IS Earth Gound, and the other provides about +16.5 Volts or -16.5 Volts relative to earth ground.

     

    That is the "Classic" way we teach Electrical Engineering Circuit Design in the US, and it would be a sensible and economical way to design it.

    Mac Pro (Early 2009), Mac OS X (10.6.8), & Server, PPC, & AppleTalk Printers
  • Csound1 Level 7 Level 7 (32,385 points)
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    Feb 5, 2013 10:56 AM (in response to Grant Bennet-Alder)

    Yes, that is what I think is happening on the DC side, as far as I could test the chassis is at earth (ground) potential (simple to test) with the 3 pin connection to the mains supply, and it floats without. Safe either way but the 3 pin connectors will occasionally trigger a ground loop state, easy to tell when your hear the buzz on the audio.

  • Csound1 Level 7 Level 7 (32,385 points)
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    Feb 5, 2013 4:47 PM (in response to medicinemanKE)

    Test at the headphone jack, the case varies a lot (especially with humidity)

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