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MBP Electrical Grounding Issue?!

AlphaDogg

AlphaDogg

macrumors 68040
Original poster
May 20, 2010
3,417
7
Ypsilanti, MI
I've noticed this for a while, but only now has it been so bad that I'm able to pinpoint the issue. A while back, I noticed that if I used my iPhone 5 while charging and my MBP while charging, the MBP would feel sort of tingly. Last night, I had my MBP in my lap with one hand on it and I went to select some music for my alarm on my iPod on my iHome and I noticed the iPod felt tingly as well. Today, I decided to investigate and I notice that my MBP feel tingly if I use it with anything that is not grounded (my iPhone charger, my iHome). Keep in mind, I'm using an 85w MagSafe charger with my 15" MBP with the extension (grounded) plug. I have it connected to a powerstrip that tells me if it's grounded or not. I know its ground detection feature works because I used to use it with an adapter for it to work in a non grounded plug and the not grounded light was on. Now that I'm using a grounded plug, the not grounded light is off. So my MBP is (as far as I can tell) grounded, but my iPhone and iHome are not.

Is there something wrong with my MBP? Something wrong with the magsafe? Any further steps to troubleshoot? As my signature states, I have another MBP which also happens to exhibit the issue. I have another magsafe adapter which I can test if needed. Keep in mind that I'm very familiar with the internal components of it, and if needed, I can check if a grounding pin or something is missing (I bought the MBP used).

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Alright I tested my second magsafe charger and it exhibits the same issue if and only if I use the same grounded extension cord (original Apple, slides into the power brick). If I use the non grounded "duckhead," it does NOT exhibit the issue. It seems that everything is isolated and should not be, so when I am touching something grounded (my MBP), I serve as the middle piece (electrolyte?) to ground the isolated electrical devices.

If I hold one hand on my MBP, lick a finger on my other hand, and touch my iPod or a metal part of my iHome, it's a pretty nice shock.
 
Any insight into the problem? Maybe people who have experienced the same thing? I know this isn't an isolated incident with my computers, I've heard of this happening before.
 
The condition that's causing the tingling sensation is not with the MBP. The other devices are floating (not grounded). If the MBP's grounded cord is not used, all devices are floating at the same potential, therefore no tingling effect. If the MBP is grounded while the other devices (iPod) are floating, you will feel the tingling while lightly touching the MBP while holding the iPod.

A slight tingling as in the above case is common, depending how sensitive your skin is. A wet finger nip could also be benign, but an outright shock, or jolt is not normal. This could be indicative of an issue with the house wiring.
 
wabbit42 said:
If you don't use the extension cable on the MBP's charger, it isn't grounded.
Click to expand...
If you don't read the original post correctly(or, god forbid, at all), you answer with something like that.

OP, my MBP sometimes feels the same, though I have not been able to reproduce it consistently. I'm guessing the body is not well isolated from the power source, hence it's trying to ground itself through you.

I seem to recall a metal piece inside the body has this very function, and that it can be removed, but I can't find the thread regarding this, perhaps your search will turn up better results?
 
The MBP case is grounded to the internal power supply ground. The device you refer to consists of copper fingers that connect the center of the bottom panel to the mainboard ground. It's purpose is to reduce radio frequency interference by grounding the center of the bottom panel. The entire bottom panel is grounded for DC and low frequency RF, but not at UHF frequencies.
 
The problem here is that the common wire is not 0 Volts, in my home country the Common wire is connected to the ground when it enters the main Meter from the Power Supply company, this will equalise the Common wire, in many countries this is not the case.
If you are barefeet on a tile or concrete floor you will feel it more than on a wooden floor, it is by no means dangerous and you should blame the Power company or your wiring for this.
If you connect the Common wire with the ground where it enters the Meter the issue will be less felt or gone.
 
I posted a thread about this a few weeks ago. I totally notice this issue, but it's only when my MBP is plugged in. Seem's they aren't grounded.
 
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