Electricity passes thru the MacBook, thru me, to anything grounded...
So, I was charging my MacBook air, its fairly warm, I touch my iMac, I notice my pinky feels tingly. I think its my iMac, freak out, touch it again to no avail. I then proceed to keep my MacBook air on my lap, and type on my apple wired keyboard connected to my iMac via a USB hub that is plugged into the wall. I feel the charge again and I realize the current is coming from my MacBook air.
Should I be worried? Because my iMac and my alum keyboard is "grounded" (well the socket this is all plugged into is not grounded... the house is old) and current goes thru, does that mean that its the positive line thats live? because if it was neutral or ground it wouldn't go thru... And how, if I should, should I approach this to apple?
EDIT: I just put my pinky on a screw on a light switch (So thats definitely grounded) and I definitely feel a current.
EDIT: The plug that I was plugged into WAS grounded and that did "shock" me but the other plugs that are NOT grounded do not shock me. and it doesn't shock me when its unplugged.
Quit using yourself to detect potentially deadly voltages. Use a voltmeter. Quit touching two things to see if you get shocked.
Check AC and DC voltages between the case and the ground terminal of a known good outlet. You might be surprised what you see.
Outlet testers tell you the polarity is correct, and that the ground and neutral are at the same potential.
I think theres a matter of Electrical Standards involved here. I dont know if USA wiring standards specify which connector in an AC outlet is Active and which is Neutral, but there is a hazard if the Active line is connected to what should be the Neutral contact and then an earth connection is made. I also know that newer outlets have 1 pin larger than the other, in theory to try to force observance of polarity, (YES, A/C current DOES have polarity)
Here in Australia, its easier with our angled slots, you cant plug an item in with the pins swapped unless it is deliberately done when the outlet is installed or the plug is put on the end of a cable.
Thats my take, you may be experiencing a neutral-to-earth leakage symptom, an ELCB would drop the circuit breaker real fast, but with reversed connections, it's anyone's game...
Essentially ALL laptops I owned that had metallic bodies exposed shocked me when using non-grounded connections (macbook air 2012, sony vaio sz-110, toshiba, others I do not remember). It is NOT an issue of reversed polarity of the connection (the laptop's power adapters are not polarized so I can invert the connection and still get shocked). This appears to be a serious design flaw in the usual switching adapter of the laptops and I am surprised it is there and not fixed.
How I fixed it for my laptops:
1) For the MBA I now use the corded connector rather than the compact one. The former is grounded the latter is not.
2) For other machines that do not have a grounded connector I have a single banana-alligator cable that goes to the ground hole in the outlet and the alligator grabs onto the ground shield of an unused USB connector. Problem solved, but very inelegant.
Hmmmmmmmm, sounds to me as though your Apple POS has a serious design flaw, the charger brick supplies +VDC to the computer, which should then go only to internal circuitry, the chassis should be on the 0VDC side of things. Take and throw it at apple for selling such junk.
the power brick is fed AC current, which it then processes down to the appropriate DC current to feed the computer, the nature of AC means that the brick can handle a power feed of either 'polarity' and works fine, sending the DC current in correct polarity to the device. OTOH, in the house wiring, you must have correct 'polarity' (even though AC current has none to speak of) because of the way the wiring connects to appliances, hence there is an 'Active', sometimes called Hot, there is a 'Neutral', which is NOT ground, and there is 'Earth'
A safety device called an ELCB works by detecting current 'leakage' from the neutral side to earth, though appliances, hands, etc and shuts off the supply, in less than a heartbeat. If the Active and Neutral connections are reversed, there is no protection, and Pinky Tingles can become major, often fatal, zaps...
Get ALL appliances checked by a COMPETENT electrician, and the house wiring too. ALL wall outlets should have the Active connection on the same side, and use 3-pin earthed plugs where possible, even get an earth wire system installed, and have all outlets updated to earthed.
Your house power supply is not just 'Lecktrickity', it deserves care and respect, lest it kills you. It can be more dangerous than an angry alligator
Reading back, this guy might also have an awesome Static problem.
Cheap carpet, synthetic fabric yarns, higher humidity, rubber or synthetic shoe soles...
Yeapp, and the ground wire in the power outlets etc is a lovely place for that static to go, or thru the metal computer chassis etc to ground
MBA still a POS tho...