Whirlpool

I've a current generation MBP and noticed recently that I was receiving painful electric shocks from it whilst operating the laptop - to the extent that I am uncomfortable/reluctant to rest my arms on the surface and had to only touch the keys/trackpad.

It doesnt happen under all circumstances but I can repeatably shock myself if I replicate the conditions (from different power points) - basically being barefoot (or in socks) on a hard flooring surface whilst charging - it doesnt occur whilst in shoes or on carpet. Whilst charging with shoes/on carpet I dont get outright shocks though I sort of suspect that I am still getting some more moderate effects.

That would suggest a grounding issue - and when I googled it there have been reports of it previously (there is also an archived thread discussing it from last year on whirlpool).

Whilst the 'consumer suggestion' appears to be replace the plug with a 3 pronged grounded adaptor head, the MBP was purchased from the US with a travel adapter pack (still under warranty) and from the adaptor heads are generally 2 pronged/of the non grounded variety.

Does anyone know what the apple policy is? - ie will they actually fix the laptop so that it doesnt have any such issues?

Whilst I can work out how to avoid the painful shocks I do have a secondary concern - I have an implantable defibrillator and having current passing through me might potentially affect the device (ie it recommended that those with such devices avoid scales that pass current through the person to measure body fat % etc). As to whether using the MBP has affected the device at times I have suspected that it has (feel as if heartrate is elevated) however its impossible to tell whether it was real or a placebo effect - particularly since I've got both things at about the same time and have used both fairly regularly since (MBP and defibrillator).

I always had soft electric shocks from my old ali 12 inch MPB

I assumed it was because there was no earth on the powerbrick so there was always a "safe" but noticeable voltage differential

4thchicken writes...

Does anyone know what the apple policy is? - ie will they actually fix the laptop so that it doesnt have any such issues?

not that i am aware of, they have known about the issue for years, it effects all the PB's and MBP's and there has never been any indication over the years that they have any interest in doing anything about it.

the only solution i know of is the one you mention - i swapped to only using the 3 pin plugs on my computers.

4thchicken writes...

I've a current generation MBP and noticed recently that I was receiving painful electric shocks

They all have the same problem. But I'd never call it painful....

Two choices really:

- Use the 3 pin power plug

or

- Get some concrete

I second that - plug in the 3-pronged cable and be done with it.

I'm very sensitive to the "furry" feeling I get when I run my fingers across PowerBooks and MacBook Pros that aren't grounded, and I get the ocassional static zap as well. That's why I used my black PowerBook G3 for so long, recluctant to move to the G4 models.

I've got a 12-inch PowerBook, and I was just wondering whether they still supply the 3 pin extension cable with the new MacBook/MacBook Pros?

andrian writes...

I've got a 12-inch PowerBook, and I was just wondering whether they still supply the 3 pin extension cable with the new MacBook/MacBook Pros?

Yes they do ;)

In regards to the three pin plug, what do you ask for when you approach an Apple Reseller?

I too have the world traveller kit, so my Australian adapter only has the two pins, how much does it cost to get the three pin plug?

Other than the shocks, are there any advantage or disadvantage to running a two or three pin in the adapter?

I do notice my power adapter getting quite hot is this normal? My first MBP, as I previously owned a Pismo, so my six year upgrade cycle finally rolled around :) I already had this swapped adapter as the first one I had was making quite an audible buzzing noise!

I've had that strange electric shock feeling a couple of times. Its far from painful, although it made my left fingers twitch a little. I just earthed the MBP and it went away (notice it has rubber stoppers preventing the shell from earthing its self unless its through your palms).

The strange thing is I have a power plug with ground, although its not a constant occurrence.

Cranial Lethargy writes...

- Get some concrete

From what I've been told, concrete is a reasonably good conductor.

Get some rubber boots :-)

TwoFruits writes...

Get some rubber boots :)
And pants if you're sitting down, also a shirt and gloves if your arms touch the surface your MBP is resting on. :-)

Err ......ok I am not an electrician but if you are getting shocked from your laptop case there is something wrong. It means that your case is live. Albeit there is not enough current to injure you significantly, it also means that there is a potential problem with short circuiting elsewhere.

I have has a mac laptop that became live as a power adapter started to go west. Subsequently it needed a new logic board which got fried one day while trying to install a ADSL modem disk. would get it checked out and it is indeed live then you need to either a) get it fixed under warranty or b) get it replaced.

Cheers Spocky

TwoFruits writes...

- Get some concrete

From what I've been told, concrete is a reasonably good conductor.

Get some rubber boots :-)

I would think concrete would be a good insulator but reinforced concrete contains a lot of metal and this would conduct if it got through the concrete "insulation".

Cheers Spocky

Spocky writes...

Err ......ok I am not an electrician but if you are getting shocked from your laptop case there is something wrong.
Yes, there's something wrong, but it's been a recurring problem in MBP's for several generations.

I have the same problem as well, my MBP is the latest version, it's the 15" 2.2 , and I have tried the power cable that came with the MBP, no "Furr" feeling from the case straight away. and it comes back right after I put the original one on.

So I think it's worth to get a 3-pin converter. Its $59 to buy the travel kit from apple. and it's more than what i really needed. Does anyone know where I can just get one 3-pin converter from?

fredluan writes...

Its $59 to buy the travel kit from apple.

I don't think the one from the Travel Kit has 3 prongs for Australia:
store.apple.com/133-622/...arnMore=M8794G/B

It supports the iPod charger, which can't/won't take earth.

fredluan writes...

Does anyone know where I can just get one 3-pin converter from?

They are $10 at travel shops and airport

But no use as Mac have a 2 pin policy and having the 3rd pin achieves nothing

mcodilla writes...

I too have the world traveller kit, so my Australian adapter only has the two pins, how much does it cost to get the three pin plug?

All mac comes with two adapters: the portable one (2 pins) and the long lead with a 3 pin plug.

Use that one.

Spocky writes...

you are getting shocked from your laptop case there is something wrong.

it's a grounding issue.... it's inconvenient, but nothing dangerous.
As people have mentioned, if you use the 3 pin connector, this issue will disappear. it only happens in some occasions if your laptop is connected to the power adapter which isn't grounded

jya writes...

it's a grounding issue.... it's inconvenient, but nothing dangerous.

for most people its not dangerous - is there any evidence that it is completely safe or wont affect people with implantable defibrillators/pacemakers? - All literature that I have found suggests that poorly grounded electrical equipment is not recommended.

4thchicken writes...

All literature that I have found suggests that poorly grounded electrical equipment is not recommended.

It's not that it's poorly grounded, rather it's NOT grounded! :D

4thchicken writes...

is there any evidence that it is completely safe or wont affect people with implantable defibrillators/pacemakers?

the voltage is also extremely low.

that I have found suggests that poorly grounded electrical equipment is not recommended.

cool, it's just *not* grounded at all :) so it must be okay

jya writes...

the voltage is also extremely low.

as would, I imagine those body fat scales (listed as things not to use)

btw, in terms of electric shocks and pain from that - is that voltage or current that is the issue? (my hazy memory from highschool physics is that there is a difference in terms of danger/risk?)

4thchicken writes...

is that voltage or current that is the issue?

it's a combination of both.

As for scale etc, they are extremely conservative in any of those.
Just like pregnant women shouldn't sleep with an electric blanket. No actual data to justify that, but they recommend not to just in case.. better safe than sorry

I have a Mac PowerBook G4, 12-inch screen, aluminium casing. I have also started to notice this electric shock, even more so after I accidentally dropped it. I usually use the 2-pin power adaptor.

I work where there's a lot of multimeter around. I plugged in my MPB with the 2-pin adaptor. I measured the potential difference between one of the screws on the left side of the laptop with the earth of the GPO. I got 0.5V. I tried another screw on the left side of the laptop, got 0.5V. Tried between the surface of the laptop in the vicinity of the mouse trackpad and the GPO earth, got 0V.

I unplugged the 2-pin adaptor, let the MPB run on battery. Measured between the screw on the left side of the laptop and earth of GPO, got 0V.

So, yes, there is definitely a potential difference. If you touch any parts which has the higher potential, it will flow to ground. Hence, the electric shock.

Calculation:
Highest voltage I got was 0.5V
Resistance of human skin (lowest value i found from internet) was 1000ohms
Then, current is I = 0.5/1000 = 0.0005A = 0.5mA

This is not really detrimental to health, according to wikipedia.

Except that what you're feeling is (probably) capacitively coupled AC – you can't measure it accurately with a multimeter. Mine gets worse when I plug it into the same socket as the TV, or one of the sockets at uni near heavy equipment.