I am intrigued to know if anyone else has noticed on beosound 8. I got my new unit and noticed when I touched metal work on front of Beosound 8 it felt 'furry'. Being an electrical engineer I immediately thought electric shock. I turned power off and couldn't feel anything, on again and felt it again. I then measured with a meter and measured 125Volts to earth/neutral. I of course returned it and the store gave me a new one. Same issue on new one, went into the store and felt the same on their unit, by turning on and off at power point (didn't have a meter to check). The store is of course is investigating, but just intrigued if anyone else has noticed this.

On my (much older of course) Beomaster 8000 this is also the fact: I measured a difference of about 120 V between the ground/earth in my home and the ground of BM8000. There is no voltage to the chassis (aluminium panels) though. I don't know, it might be normal?

What is weird is that in  BS8 this voltage seems to be on the chassis (at least in your two cases). Shouldn't the chassis be either isolated or connected to earth/ground with a three prong plug due to safety reasons?

i find it happens with a lot of electrical equipment, but could never put the right adjective to it, but when i read furry, i thought, that's it!  I find that when i charge my macbook it also has this feeling when i run my finger lightly over metal components of the laptop or other electric devices.

I don't think it's a fault, it's just energy :-)

I'm no electrical engineer, but living as I do in Spain and having been used to the 'normal' 3 pin UK plug, it still amazes me that the 2 pins on the mains plugs of my electrical equipment can plugged in in 2 different ways! One way, then turned 180 degrees and plugged in again irrespective it seems of postive/neutral considerations.

Those with knowledge of wiring systems have tried to explain this to me but without much success!

It just sems strange when for many years in the UK it was always emphasised how important it was to connect up a 3 pin plug correctly viz-a-viz the postive and neutral wires. 

Michael:

I find that when i charge my macbook it also has this feeling when i run my finger lightly over metal components of the laptop

my Macbook semi-pro too :-)

and other equipment in the past - not so sure about B&O tho'

See the type sticker of the Beosound 8 (or pretty much any halfway modern piece of kit that runs on two-prong AC power) and you will find it is classed as a "doubly insulated" AC device (two concentric squares).

This means that neither of the AC inlet wires has any electrical connection to the case or any exposed connector of the device. It absolutely does not matter which way the plug is inserted.

The ~120V AC voltage you see on the case is probably some parasitic capacitive / inductive connection from the AC fields inside the device. It can't provide any real current to speak of because the impedance is very high. Digital multimeters will show it, but it will never be enough to cause an electric shock. If you had an old skool analogue multimeter, it probably would not show any voltage there.

This "furry" feeling... that is indeed the best name for it ever! I can feel it in most of my B&O kit which has exposed aluminum surfaces, but usually only if I very lightly move my finger on it. They definitely have nothing wrong with them.

***

The situation changes if the device is supposed to be connected to a grounded AC connection (lke PC power supplies for example) with a separate protective earth connection. They may have noise suppression capacitors across the AC input to the ground. They will allow some current through, and if you connect it to a non-grounded (two-wire) socket, the case of the device will again float somewhere between 0 and full AC voltage, with a much smaller impedance than in the previous case. It still isn't dangerous, but may feel quite nasty and may damage some badly protected signal connections if you try to connect / disconnect other devices with the mains cords plugged in.

tournedos:

See the type sticker of the Beosound 8 (or pretty much any halfway modern piece of kit that runs on two-prong AC power) and you will find it is classed as a "doubly insulated" AC device (two concentric squares).

This means that neither of the AC inlet wires has any electrical connection to the case or any exposed connector of the device. It absolutely does not matter which way the plug is inserted.

The ~120V AC voltage you see on the case is probably some parasitic capacitive / inductive connection from the AC fields inside the device. It can't provide any real current to speak of because the impedance is very high. Digital multimeters will show it, but it will never be enough to cause an electric shock. If you had an old skool analogue multimeter, it probably would not show any voltage there.

This "furry" feeling... that is indeed the best name for it ever! I can feel it in most of my B&O kit which has exposed aluminum surfaces, but usually only if I very lightly move my finger on it. They definitely have nothing wrong with them.

***

The situation changes if the device is supposed to be connected to a grounded AC connection (lke PC power supplies for example) with a separate protective earth connection. They may have noise suppression capacitors across the AC input to the ground. They will allow some current through, and if you connect it to a non-grounded (two-wire) socket, the case of the device will again float somewhere between 0 and full AC voltage, with a much smaller impedance than in the previous case. It still isn't dangerous, but may feel quite nasty and may damage some badly protected signal connections if you try to connect / disconnect other devices with the mains cords plugged in.

I believe it is still possible to have type "Y" capacitors (either a single Y1 or two Y2 parts in series) from live and neutral to "dead" metal (i.e. otherwise insulated from the current carrying parts of the appliance), even in double insulated appliances, for EMI suppression reasons. These capacitors are really low in value and pose no safety risk and are allowed by the applicable safety standards. These are more common with switching supplies which have their own RFI emmission issues. Could this be the case here?

Puncher:

I believe it is still possible to have type "Y" capacitors (either a single Y1 or two Y2 parts in series) from live and neutral to "dead" metal (i.e. otherwise insulated from the current carrying parts of the appliance), even in double insulated appliances, for EMI suppression reasons. These capacitors are really low in value and pose no safety risk and are allowed by the applicable safety standards. These are more common with switching supplies which have their own RFI emmission issues. Could this be the case here?

That could very well be the case, although many devices with such problems will be using a grounded AC input nowadays - like some laptop power supplies, which don't need the ground for anything else than passing the EMC measurements.

Regarding the strict difference between live and neutral in the UK... I suspect it is some historic safety requirement in old wiring standards. Possibly to ensure a ground resistance low enough to blow the fuse when a device with exposed metal develops a ground fault.

EDIT: no, it must be because the damn fuse is in the plug, unlike anywhere else! It must disrupt the live wire when it blows, not neutral!

It does not affect operation, therefore it is not faulty. All B&O equipment does this on it's aluminium parts. No one seems to know WHY. Inside my BeoVision 3 there is a little wire that is attached to the front aluminium plate... so, the charge clearly has a function... maybe it's the earth, considering that none of the items are earthed via the AC plug...

See here for a brief explanation from John Dawson (Arcam) and here for a customer explanation from Panasonic.

Thanks to everyone for answers. The capacitors makes sense, explains why it was half the mains voltage. It will be interesting what answer comes back from B&O.

One thing I have noticed in using my Macbook ... when it is feeling furry ... and then when SWMBO runs her finger along the edge of my ear ... its furry too :-)

I am sure you are aware that the only way to test this properly is not with a high impeadance meter but to perform an insulation test with a suitable meter. I think this will tell you all is well :)

elephant:

One thing I have noticed in using my Macbook ... when it is feeling furry ... and then when SWMBO runs her finger along the edge of my ear ... its furry too :-)

Have you got hairs growing out of your ears Ed???

Jonathan:

Have you got hairs growing out of your ears Ed???

shhhhh you promised not to tell !!!