View Full Version : A very tingling phone call on my 3GS

1st August 2010, 03:01 PM
Yesterday I took a call on my 3 GS while it was tethered to my MacBook (late 2008 aluminium unibody). The MB was on a metal tray attached to an anaesthetic machine (a gas-driven one), and was plugged into the mains.

I felt a stinging sensation on my ear and I thought that the anti-glare film must have been coming off, but I couldn't find any rough edges. I then held it up to my ear again and felt the sharp stinging sensation, which was also accompanied by a soft buzzing sound.

This sounds ridiculous, but I think it may have been arcing electricity to my ear.

It stopped as soon as I unplugged the iphone from the MacBook.

I'm not a troll, I love my Apple gear, but I just thought I'd share this experience.

1st August 2010, 04:21 PM
Mine does that, too.

1st August 2010, 05:10 PM
so does mine

1st August 2010, 05:30 PM
Switched-mode power supply with a floating earth. What you are feeling is high voltage electricity. You can feel it on the unibody macs if you use the power adaptor without the earthed plug. It's harmless, but annoying.

Edit: Here's a post on MacRumors that I found when I first noticed this a couple of years ago:
Mac Forums - View Single Post - Macbook Air electric shocks and tingles (http://forums.macrumors.com/showpost.php?p=7229762&postcount=98)

1st August 2010, 11:25 PM
Interesting. On reading the macrumors entry, I think I should use the earthed extension plug when I plug my Mac or even iPad in when around patient on the operating table.

Electrical safety is a big thing in anaesthesia. Microshock is a
particular danger, when a patient becomes the earth and charge travels down a central line (filled with highly conductive saline and/or blood) straight to the heart. As little as 10 mAmp current can be fatal.

To date, to save space, I have been only carrying the two pronged adaptor for MacBook and for ipad I have been using the USB plus a USB extension with the 10W adaptor and using the optional earthed adaptor at home. I don't often put the iPad in charge but I think I will now take the earthed one to work for patient safety reasons and I will inform my other anaesthetist friends, many of whom also use aluminium unibodies on the anaesthetic machine, likewise.

It would probably be okay if I plugged into the equipotential earthed power point, but that's on the pendant hanging up from the ceiling (a hangover from the days of flammable vapours), whereas I just plug my gadgets into free power points on the back of the machine.

2nd August 2010, 12:24 AM
Mine also does this, I thought it was common throughout all phones.

2nd August 2010, 10:57 AM
Mine also does this, I thought it was common throughout all phones.

It might be, I wasn't having a go at Apple, but I wish that it was common knowledge that it was common to all phones.