Potential Electric Shock Hazard ?

Was using my new iPad whilst plugged into the Mains USB Charger
and found I was getting a tingling sensation through my fingers
from the aluminum case.

I found that if I measured between earth and the case I got over 89 vac !?

Anybody else experiencing this and is my iPad faulty ?

Thanks

Message was edited by: DH2010

iPad

Posted on Aug 17, 2010 3:12 PM

Reply
20 replies

Aug 19, 2010 1:16 AM in response to DH2010

I took my iPad back to the apple store and they looked at me as if I was mad.

After a long and painful discussion, they changed the charger which in my case fixed the problem. It is still the one with a dummy earth pin though, which is worrying given the fault I and others have experienced.

Apple don't seem to take the complaint seriously.

Sep 10, 2010 10:54 PM in response to red555

there's absolutely no danger or health risk here. please don't be paranoid... it's caused by an oscillation of the ground in your devices which conducts a small current through your body. afaik, it's just a leakage common to almost all power supplies and not intentional. if it really bugs you, put shoes on and stand up and it will probably go away. the voltages and currents here are miniscule and cannot hurt you.

if you're interested in what actually happens, i posted what i know about the phenomenon on some forum i've never heard of (yeah ok i know...) but here's the link: http://www.last-word.com/contenthandling/showtree/id/4822/page/1.html

Sep 15, 2010 3:48 AM in response to Kristian Sims

All very interesting

The power supply for the iPad is a double insulated device and therefore doesnt require an earth (Look at the writing on it and you will see a box in a box symbol). It is the only part of the system that carries mains voltage 55/110/230 at any time

The supply to the iPad itself, either from the power suply of from a USB socket is 5v +/- a bit at max around 1 amp

So 1) there are no voltages above 5V generated or supplied in the iPad

2) the iPad metal case is connected to the 0v rail (Chassis) of the USB cable and so should not be at any potential ideally, its used as the 0v reference. If it was above 5V the the potential difference between the supply and its reference would be zero and the iPad wouldnt be able to charge (the batteries may keep it running)

3) Any fault voltage would be 55v/110V in the US or 230v/440v in the rest of the world as these are the line voltages in use. As the voltage is not this it suggests its an induced charge

So if you are showing such a high voltage then there are only a few potential causes

a)your charger is faulty and is putting 80v out of its 0V line. It would have to be putting 85V out of its +5v line to match this or your iPad wouldnt show charging as it needs to maintain the 5v PD. Easy to measure and reasonably feasable/ also swapping to a cable from a USB port would stop the problem

b) its an induced voltage from a nearby AC source. Unlikely as the chasis is on the 0V rail so again the +5v line would have to be at 85V to get a charging indicator

c) Its static from you. This is the most likely, its common for folks to be charged to several thousand volts (but almost no current) especially if they are wearing insulative shoes/cloths and have nylon carpets. What you feel is the discharge into the ipod Chasis, which cos its not actually earthed is slow

d) The object you measured the PD to is actually the charged object. What did you use your multimeter between when you measured the PD? Try measuring the case to the earth pin on a socket

Also try measuring the current as well as the voltage. 0 for both for my iPad when charging

If there was a true 80V plus on your case you would also be able to light one of those electricians screwdrivers with it. Bet you cant

May 31, 2011 11:24 AM in response to DH2010

No matter what anyone says this is not static. The proof being if it was, is when you touched the aluminium case any static discharge would be momentary and only repeat later after your body has built another static charge.

This is a 50 herz induction being felt through the fingertips probably due to skin or surface effect due to there being a dummy earth pin on the plug. This is an ungrounded earth pin on the plug that is plugged into the 240 vollts mains.

It is a design fault and slight though it is, there is a potential danger from any metal cased object becoming serious if the earth pin is not connected and the power supply becomes faulty.

Apple need to address this problem on both the ipad and ipad2 as it happens on both.

I feel Apple are not treating it seriously because of the cost of replacing millions of power adapters.

Perhaps the UK Trading Standards Office need to be informed

May 31, 2011 12:30 PM in response to femina

femina wrote:

This is a 50 herz induction being felt through the fingertips probably due to skin or surface effect due to there being a dummy earth pin on the plug. This is an ungrounded earth pin on the plug that is plugged into the 240 volts mains.

Eh? An ungrounded earth pin. So what you are saying is that a pin connected to the earth terminal in the socket is not earthed?


May 31, 2011 1:21 PM in response to DH2010

I am convinced that you have a hardware problem with your charger. I did some checks just to satisfy myself.


The first test doesn't prove much because U.S. power is different from most of the world. However, I measured zero VAC from earth ground to the case. I then reversed the position of the AC plug and again I measured zero VAC from earth ground to the case.


In my second test, I eliminated the effects of the different power systems. The iPads are identical and the chargers are identical. The only difference is mechanical - the physical arrangement of the prongs, In any event, with the charge not plugged into AC, I measured infinite ohms from the case to each of the prongs. I'll wager that you do not get infinite ohms from at least one of the prongs.


Message was edited by: Philly_Phan

Jun 1, 2011 12:48 AM in response to DH2010

Yes it is a charger hardware problem it is called a dummy earth prong on the plug.

In the UK we have a square 3 pin connector and the actual part that pushes into the mains socket slides onto the apple's two wire connector converting it into a connector that can be plugged into the 240 volt mains, and it is unacceptable that apple would use such a shoddy system on both its ipad and ipad2.


Yes gummsie the earth prong serves only one purpose on the apple and that is to unlock the live and neutral connections on the mains socket. If you are unfamiliar with our plugs, the earth prong is slightly longer than the live and neutral so as it is inserted it lifts the locking gate that prevents live and neutral connecting until the earth has already made contact. That of course means you need a 3 wire setup from the ipad to the charger and plug. If you only have two wires then the earth prong has to be a dummy and the potential hazard of a metal case going live with 240 volts AC at some time in the future is hugely increased. This possible risk is unacceptable and should be addressed by apple and not ignored until someone gets seriously injured or even killed.

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