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[Lyle Williams]

I had a few times when I felt a slight tingle on the side of my arm when it came into contact with a sharpish point on a rack case.

I had some trouble reproducing the effect, but finally tracked it down to an iPod charger.  I was noticing the tingle but not noticing what I was doing with my hand.  Anyway, there is 90VAC @ ~20uA on the iPod case.

It took a while to track down because:
I wasn't sure that it wasn't just the sharpness of the rack case.
I only felt it when there was the lightest of grazing contacts - I felt nothing with firm contact.
I could only just feel it, and only when the iPod was in my left hand.
Many of my iThingos are in rubber cases.
It didn't feel like 50/60Hz AC.
Normally I was focused on the music.

[Mike Sokol]

I had a few times when I felt a slight tingle on the side of my arm when it came into contact with a sharpish point on a rack case.

Did this case have some sort of rack mount power strip? If so, I wonder why the case wasn't bonded to the EGC (Equipment Grounding Conductor) via the rack screws? And I know that I'm guilty of throwing a plastic power strip in the bottom of a rack to power a few pieces of gear. But if that's the case, then that same gear should bond the rack to the EGC. 

So how did the leakage current (and the resultant voltage) end up on your rack? Was the iPod just laying on a rack case that had no other AC powered gear?

The interesting thing is that there's been several electrocutions in the last few years from iPhone chargers electrifying iPhones that were picked up by people while in the shower. But these turned out to be aftermarket chargers that developed internal line-to-chassis shorts. I've measure similar sub-milliamp leakage on my own Apple iPhone chargers, which is below UL limits for non-grounded appliance leakage.

This is a great illustration that ANYTHING plugged into an AC receptacle can leak current back to earth. Just how leaky it is changes your experiance from a barely noticeable tingle to a severe shock that can electrocute you.

[Lyle Williams]

That was a problem in my initial troubleshooting.  The rack case was grounded perfectly.  It wasn't the source if my volts, but the destination.

The charger isn't genuine, but is a reputable brand with local electrical authority approvals. 

If I sat next to the rack and picked up the iPod on charge, I wouldn't feel anything - a broad area of my arm was in contact with earthed metal.  Only when standing next to the rack holding the ipod on charge would I make contact with a small enough point on my arm to feel the volts.

[John Roberts {JR}]

I've felt <1mA currents, while the sensation is not a strong obvious electrical shock but a maybe... Was that a real shock, or some excitable nerves in my arm misfiring?

20uA may be acceptable leakage for some products. IIRC I had a kitchen kettle that leaked a lot more than that into it's ground lead, that was floating in my kitchen outlet wiring so around. Actually the leakage was coupled into other appliance grounds via a 3 wire outlet strip.  (I replaced that kettle for a 2-wire plug version).

JR

[Jonathan Johnson]

I wouldn't even describe it as a tingle, but a friend had a home stereo system which exhibited an interesting behavior:

When powered on, if you rubbed your finger across the brushed aluminum front panel of the receiver, the texture of the panel felt different (almost kind of a vibration) than when it was powered off. Just touching the panel without rubbing it didn't produce any noticeable effect.

Never investigated it further than "hmm, that's interesting."

[Mike Sokol]

just wondering if any of you have ever measured how much current is flowing when you do a 9 volt battery "tongue test"? Of course, while you can almost never feel any voltage across a 9 volt battery with dry fingers, putting on your tongue is another story. Also, almost any current through a cut in your hand feels a lot bigger than it really is. Wet saline fluid is a really good electrical conductor.

[Frank Koenig]

When powered on, if you rubbed your finger across the brushed aluminum front panel of the receiver, the texture of the panel felt different (almost kind of a vibration) than when it was powered off.

I, too, remember experiencing exactly this. Not so much lately, I think most stuff is just better grounded or better isolated these days -- a very good thing. -F

[Lyle Williams]

It seemed to be feeling stronger as time went by.  It was up past 100v when I measured it.

I have now permanently forced the charger to be at ground potential.





(It has been sent to landfill.)

[Hayden J. Nebus]

Has anyone else been bit by a newfangled shopping cart (with the "parking lot loop" activated brakes?)

I routinely get zapped by these things while grocery shopping, sometimes once every 5 minutes! It's more a bite than a tingle too.

[ProSoundWeb Community]