The Buzzz...

Hi vermin, it sounds like you have an un-earthed appliance. The neutral side of the power is probably close to (if not on) ground. The live side may have some leakage to the chassis, which can (capacitively) charge up to some AC voltage that you can feel. If all is normal, the leakage resistance should be some MΩ, so you probably won't get a nasty shock. I still prefer earthed-chassis appliances.

Jorrie

vermin could get a portable insulation tester. This can drop a couple of thousand volts over his stereo and check it's insulation. It's possible that he may have no stereo left afterwards, so be careful vermin. Don't hold the meter leads when you press 'test' or you may end up like my late lamented bathtub. How can you have a metal chassis with no earthing cable vermin ? Is it a plastic double-insulated case ? All in all, I think it would be safer just to enjoy the sensation that others can't detect. Just be glad of your sensitivity. Do you have especially sweaty palms, or wear lots of Nylon ?

<Is the case hot? If I put one hand one the case and grabbed a water pipe with the other, would I get the #*&% shocked out of me.>

You said it all.

< have tried to show this to people, and some cannot feel anything.>

Poor duffers!

So is the case lit by all 110V AC or is it divided to, say, 50V AC?

This is just to add a little detail to what Jorrie wrote. It assumes your equipment is not in any way defective:

If you hang (so-called) double-insulated equipment in mid air, the outside of the case will be at some point intermediate between the live and neutral potentials - but not always in the middle. However, once you connect a partial conductor (yourself) to the case, the case voltage will be quite low - the internal resistance should be so high that you cannot pass more than a few tens of microamps. In answer to the 50V question. as you notice a difference when reversing the plug, it would seem that the case is not midway between the two supplies.

However, with regard to your stereo, I suspect that this has an external ground connection available. If so, it is designed to be used with other equipment, and it is expected that the grounds of these equipments will be interconnected (preferably not via the screen of signal wire, though this is not uncommon). To avoid problems with ground loops, it would be expected that exactly one of the equipments would be earthed to the general household earth.
Some of these equipments can have internal interference filters on the mains inputs; these will often have small capacitors between the inputs and ground. However, if these equipments are in proper working order, reversing the plug polarity should have no effect (at least as far as the current through the filter is concerned, as the filter should be symmetrical).

So why is the back of your hand especially sensitive to this - I've no idea, but I've noticed the same. Your tongue is even more sensitive, but I wouldn't recommend trying this out unless you know exactly what is happening inside the equipments.

So why is the back of your hand especially sensitive to this..

vermin have hairs on the back of their hands. Static etc ? Sweaty palms should produce some sort of enhanced effect, but probably not as much as a tongue.

'Supermarket trolley shock' is one that I've not felt for a while. I wonder if they have changed the wiring on cabinets, or wheels on trolley's. 'tis a mystery.

I speak from practical experience - my sweaty palms don't have the same ultimate sensitivity as the backs of my hands (even when those are dry); but the sensation in the palms soon overtakes that in the backs of the hands as the level increases. I suspect it is something to do with the lack of distracting information - you use the fronts of your hands so much that something is always going on there...

Also, I endorse vermin's comment that lower life forms (vermin and other so-called gurus) appear to be able to sense these electric currents at levels that are way below what higher creatures can. (We had some old "mineral-insulated" lampholders had leakage levels that I could feel, but the available current turned out to be orders of magnitude below the most stringent safety requirements).

If I put one hand one the case and grabbed a water pipe with the other, would I get the #*&% shocked out of me.

Could it be that some dyslectic part of you is getting things mixed up. Maybe it's the pipe that attracts the back of your hand and you are getting it all the other way around. (No, not like in batteries)

In case I got it all wrong I would suggest you see your local 'sparky' (Australian for electrician, I knew you knew that). See were this one ends up.

Its been fun again mate. Ky.

It is definitely a possibility!!! From time-to-time I do hear something flowing through my water pipes... So what the heck can that be!!!

water

Your dreams?

It might be an interesting experiment to take a volt meter and measure the AC voltage between the case of your appliance and the ground pin of the outlet... in both plug orientations.

Bill

Or the case and your testicles?

With an imagination like that, you have a promising future as a civil servant in China!

I agree. This is the most practical way to determine the situation.

Also, does this occur with all outlets of this sort? If not, you may just want to test (inexpensive plug in unit) whether your socket is properly wired.

An electric shock can cause most people to jump up and down, so has this already happened? The CR4 readership is poised upon the answer.....

hello...

I tink thats due to electrodinamic vibrations- it happens many times in power transformers , and in any electric device that use this type of equipement!

but in power transformers you realise it better!