Getting zapped off 2.1 speakers and sub

[zetsubou]

Hi everyone, I'm trying to figure out where to begin troubleshooting this issue.
My speaker setup has under performed from day 1, confirmed by the retailer, but they wanted me to pay the $70 return shipping fee and I decided to just deal with it.

I realised today that I get painful shocks from touching the metal parts on both the sub and speakers. They're powered independently by transformers.
Speakers -   18VDC 3.3A
Sub -   +-30VDC 2A
The sharp tingling occurs regardless of ON/OFF switch position on both the sub and speakers.

Am I onto something here or do I just not know how to use a multimeter?

[Bushougoma]

Any change when taking that measurement in LoZ mode?

[iampoor]

Is your outlet wired the right way??

[Armadillo]

2 Situations; Identify the faulty one.

1) 18VDC faulty - unplug it and test metal surface with test pen
2) +/-30VDC faulty - unplug it and test metal surface with test pen

The ground fault interrupter should trip if the leakage current has exceeded trip threshold [e.g. direct shorts].

[shakalnokturn]

This is a common problem due to the way SMPS are built, they always have some leakage current from primary to secondary and when all equipment is unearthed you can feel it tickle you, it is usually not dangerous though (measure AC amps from ground to earth) it is quite annoying.

The answer is to earth at least one point of the common ground, but then earthing one piece of equipment only can run you into other problems when disconnecting cables between them: The typical example is having one piece of equipment un-earthed and one earthed, when connecting an RCA jack the center pin will touch before the shield (ground) sending the floating 100V or so you're measuring to the ground through an IC's input, that is sometimes enough to destroy the IC.

[paulca]

Would this not just pop an RCD trip instantly?

[mikerj]

Would this not just pop an RCD trip instantly?

No, you need quite a bit of earth leakage current to trigger an RCD, at least 5mA and maybe as much as 30mA for the type used in homes.  The leakage you get from the interference suppression Y capacitors on SMPS should be less than 0.5mA.

[Armadillo]

The measurement is in AC mode. Not normal.

[madires]

Yay! You just found the EMI suppression cap of the SMPSU

[Armadillo]

Yah, that's a normal misconception.
The nominal Y cap is at least 1.2Mohms hence you should not be able to measure that magnitude of AC voltage at the output. No way. It's a fault.

[Bashstreet]

100+ AC through SMPSU is not normal it is faulty i would not use it nor poke around.
Get new one not much point try repairing it unless you know what you doing 

[shakalnokturn]

Just for comparison I made the measurement on an unearthed, unloaded Toshiba PA2444U laptop PSU.
I'm in a 230V country. Secondary ground to earth voltage is 96V (distorted half sine AC of course) into a 10Mohm meter, leakage current available is 80µA.
Don't believe what you're told however, look a SMPS schematic and think for yourself.

You can either:

-Live with getting zapped.
-Earth the equipment.
-Substitute the SMPS for something equivalent with an iron core transformer.

[tooki]

100+ AC through SMPSU is not normal it is faulty i would not use it nor poke around.
Get new one not much point try repairing it unless you know what you doing 

Yes it is! 100V is on the high side, but not at all unusual. (I could swear Bigclive did a comparison of a bunch of USB chargers, measuring this, but for the life of me I can't find it.)

https://www.eevblog.com/forum/beginners/phone-charger-gives-electric-shocks-how-to-measure-voltage/25/
https://www.eevblog.com/forum/beginners/y-capacitor-current-leakage-electromagnetic-interference-(emi)-problem/

Use a multimeter to measure the current of the leakage. It should be under 85uA, according to one source I read.

[Shock]

According to the AS/NZS 3760:2010
Class II
Measure the current flowing between accessible unearthed metal and earth
Maximum leakage should be no greater than 1mA

[Armadillo]

Layman view or standards?

https://en.wikipedia.org/wiki/Extra-low_voltage

[Armadillo]

Layman view or standards?
https://en.wikipedia.org/wiki/Extra-low_voltage

Wikipedia is not a reliable source for standards, also standards can be country specific.
The one I refereed to AS/NZS 3760:2010 is specific to Australia/New Zealand.

I was not replying to your message. Your view was sound.
Regarding reliability, refer to the actual standards referred therein.

[Armadillo]

care-less laymen speech may cause life.
if you want to err, always err on the safer side.
Look at the way it was hooked up to the equipment and the way it was measured [Not open, not unloaded].
Cheers;

[shakalnokturn]

The standards define a maximum voltage that should be safe to touch.  They also specify safe leakage current limits. (Having a 10kV source with an internal resistance of 1Gohm is not dangerous to touch although 10kV sounds scary.)

Then on top of the standards there are RCD/GFCI devices for further protection, I'm not saying getting zapped by your subwoofer is not a concern and that it should be overlooked, failing to understand the problem is IMHO at least as dangerous as overlooking a possible fault.

[madires]

Yah, that's a normal misconception.
The nominal Y cap is at least 1.2Mohms hence you should not be able to measure that magnitude of AC voltage at the output. No way. It's a fault.

Doesn't that depend on the input impedance of the DMM? The higher the input impedance the lower the current, the lower the voltage drop across the cap, the higher the measured voltage?

[Armadillo]

Armadillo please provide exact details instead of saying "look" and words like "open" and "unloaded" which could mean anything.

it meant the power supply not connected to anything, left floating.
If you noticed, the word "unloaded" was used by shakalnokturn

OP power supply is connected to the equipment. The metal part exposes 100 over volts AC.

Edit: I supposed Australian codes are very consumer protective? Will you accept 100 over volts AC on metal parts and it bites? and come some wise crackos point to the Y cap and says is normal???

[Armadillo]

Yah, that's a normal misconception.
The nominal Y cap is at least 1.2Mohms hence you should not be able to measure that magnitude of AC voltage at the output. No way. It's a fault.

Doesn't that depend on the input impedance of the DMM? The higher the input impedance the lower the current, the lower the voltage drop across the cap, the higher the measured voltage?

Yeah, you are right. But the context is the OP photo as above.

Edit; it means a modicum of current draw will drop the voltage e.g. filter caps. If the exposed metal part is connected to the earth, will it read the same? Should check the earth continuity then, or the power supply.

[paulca]

If I bought a metal cased device that didn't have an Earth I would point it out to trading standards.  As I understand it, it would not pass British safety standards for mains operated equipment.

Regardless of standards, if I got a mains zap off a metal cased product it would be returned to the vendor with a letter of complaint and a threat of containing trading standards or naming and shaming them in the press if they didn't pay all postage costs and replace the unit with a safe one.

I don't care what amount of mains voltage American's or Australian's accept to get zapped by, nor do I really care what mains voltage/current leakage the British standards allow, I do not expect to get zapped by a mains device and then expect to keep it attached to any plug socket!

Here is a sensible question.

Would you want this device to be sitting on your living room floor while your child plays on the carpet next to it?  A child with wet hands.

[madires]

If I bought a metal cased device that didn't have an Earth I would point it out to trading standards.  As I understand it, it would not pass British safety standards for mains operated equipment.

Like smartphones with a metal case?

Regardless of standards, if I got a mains zap off a metal cased product it would be returned to the vendor with a letter of complaint and a threat of containing trading standards or naming and shaming them in the press if they didn't pay all postage costs and replace the unit with a safe one.

Basically I'm with you, but the EMI suppression cap in SMPSUs is needed to comply with CE. A side effect is the mains referenced low current passing the cap. The cap should be a Y class type for safety and should also have a low capacitance to limit the current. Of course there are cheap SMPSUs which don't adhere to the rules. A metal case or case with exposed connectors isn't the problem, it could be a class II device (double insulated). You get zapped by the SMPSU.

I don't care what amount of mains voltage American's or Australian's accept to get zapped by, nor do I really care what mains voltage/current leakage the British standards allow, I do not expect to get zapped by a mains device and then expect to keep it attached to any plug socket!

You are free to replace all SMPSU wall warts and bricks with classic transformers.

Would you want this device to be sitting on your living room floor while your child plays on the carpet next to it?  A child with wet hands.

If you have the active speaker system connected to a PC it would be grounded via the PC.

[Armadillo]

You should focus on the subject and context than finding skeletons to reply.

Smartphones are battery operated and even when it is connected to the charger, we don't get a electric shocks [metal case], so your story on the Y-cap cannot be substantiated.

In any case, where the exposed metal surfaces exceed the safety extra low voltage, you failed the electric codes, regardless of what you want to say.

It would be almost not wise to say the current is limited. The shock though not lethal fatal may create a involuntary action that caused it to belethal fatal.

No, I am not impressed with your EMI or Y-cap knowledge.

https://www.edn.com/electronics-blogs/power-supply-notes/4414411/What-does-SELV-mean-for-power-supplies

[paulca]

I have NEVER received a shock or even a buzz off a mains powered device.  At least not one I hadn't opened and wasn't poking around inside while it was switched on.

I haven't checked my wall warts but based purely on the size of a few phone chargers they may be SMPS.  If one of them gave me a shock or even a buzz I would bin it.  If it was brand new I would send it back.

A mild buzz while using something like a deep fat fryer or kettle could result in someone jumping and pulling the hot oil / water down round themselves.

Mains devices should NOT, EVER, buzz or shock you unless they are broken or crap.  It's simply dangerous.  Most people I know would return it or bin it.

Again.  Would you like your child to be crawling around the floor with devices that might shock them sitting around?

If it buzzed me, I would not be connecting it to my PC.

[eeviking]

If the equipment (smps) have Y caps they should be connected to earth ground.
If you get a zap and can measure high voltage they are not!

There are only two possible faults:
1. The equipment have a broken or not connected ground wire from the mains plug to chassis/psu. (return or fix the equipment)
2. Your mains power outlet / extension cord have a broken or not connected earth ground wire. (fix your mains installation)

We see this a lot in EU when people connect 3 pin equipment to 2 pin extension cords without earth.

[tooki]

Like it or not, it is common and is normal.

If I bought a metal cased device that didn't have an Earth I would point it out to trading standards.  As I understand it, it would not pass British safety standards for mains operated equipment.

Every MacBook made for years now is metal-cased, and when using the charger with the 2-prong plug, it's ungrounded, and sometimes can tingle. Do you seriously believe that Apple could get away with selling millions of units of product that violate the rules? And that Apple wouldn't have had it certified?

Or is it perhaps more likely that your understanding of the rules is incomplete?

[Shock]

Paul, double insulated devices often have no mains earth/ground wire attached but still can use a metal chassis. Again standards are country specific, look up your local standards.

Armadillo, you can be electrocuted by smartphones, the battery has little to do with it. Metal chassis pose an additional risk should things go bad.

Noone is saying that the device posted is necessarily safe, this is what investigation and testing is for (should you be skilled enough not to put yourself at additional risk during the process).

This post by Peter Green on stack exchange basically sums up what I'm talking about:

Switched mode power supplies use what is known as a "flyback converter" to provide voltage conversion and galvanic isolation. A core component of this converter is a high frequency transformer.

Practical transformers have some stray capacitance between primary and secondary windings. This capacitance interacts with the switching operation of the converter. If there is no other connection between input and output this will result in a high frequency voltage between the output and input.

This is really bad from an EMC perspective. The cables from the power brick are now essentially acting as an antenna transmitting the high frequency generated by the switching process.

To suppress the high frequency common mode is is necessary to put capacitors between the input and output side of the power supply with a capacitance substantially higher than the capacitance in the flyback transformer. This effectively shorts out the high frequency and prevents it escaping from the device.

When desinging a class 2 (unearthed) PSU we have no choice but to connect these capacitors to the input "live" and/or "neutral". Since most of the world doesn't enforce polarity on unearthed sockets we have to assume that either or both of the "live" and "neutral" terminals may be at a sinificant voltage relative to earth and we usually end up with a symmetrical design as a "least bad option". That is why if you measure the output of a class 2 PSU relative to mains earth with a high impedance meter you will usually see around half the mains voltage.

That means on a class 2 PSU we have a difficult tradeoff between safety and EMC. Making the capacitors bigger improves EMC but also results in higher "touch current" (the current that will flow through someone or something who touches the output of the PSU and mains earth). This tradeoff becomes more problematic as the PSU gets bigger (and hence the stray capacitance in the transformer gets bigger).

On a class 1 (earthed) PSU we can use the mains earth as a barrier between input and output either by connecting the output to mains earth (as is common in desktop PC PSUs) or by using two capacitors, one from the output to mains earth and one from mains earth to the input (this is what most laptop power bricks do). This avoids the touch current problem while still providing a high frequency path to control EMC.

Short circuit failure of these capacitors would be very bad. In a class 1 PSU failure of the capacitor between the mains supply and mains earth would mean a short to earth, (equivalent to a failure of "basic" insulation). This is bad but if the earthing system is functional it shouldn't be a major direct hazard to users. In a class 2 PSU a failure of the capacitor is much worse, it would mean a direct and serious safety hazard to the user (equivilent to a failure or "double" or "reinforced" insulation). To prevent hazards to the user the capacitors must be designed so that short circuit failure is very unlikely.

So special capacitors are used for this purpose. These capacitors are known as "Y capacitors" (X capacitors on the other hand are used between mains live and mains neutral). There are two main subtypes of "Y capacitor", "Y1" and "Y2" (with Y1 being the higher rated type). In general Y1 capacitors are used in class 2 equipment while Y2 capacitors are used in class 1 equipment.

So does that capacitor between the primary and secondary sides of the SMPS mean that the output is not isolated? I've seen lab supplies that can be connected in series to make double the voltage. How do they do that if it isn't isolated?

Some power supplies have their outputs hard-connected to earth. Obviously you can't take a pair of power supplies that have the same output terminal hard-connected to earth and put them in series.

Other power supplies only have capactive coupling from the output to either the input or to mains earth. These can be connected in series since capacitors block DC.

Here is a double insulated device:

[Armadillo]

Paul, double insulated devices often have no mains earth/ground wire attached but still can use a metal chassis. Again standards are country specific, look up your local standards.

Armadillo, you can be electrocuted by smartphones, the battery has little to do with it. Metal chassis pose an additional risk should things go bad.

Noone is saying that the device posted is necessarily safe, this is what investigation and testing is for (should you be skilled enough not to put yourself at additional risk during the process).

Except PELV circuit which is also double insulated with earth/ground wire.
The codes regarding the SELV/PELV are similar in all parts of the world.
The exposed metal parts cannot exceed the SELV voltage and it may also be considered as "LIVE" if the charge exceed the value defined in the "Mandatory" codes of compliance

The focus must be on OP safety as he described as "Painful Shock" and not on anyone glory of knowledge. [that will includes myself].
May we channel our energy on that. 

[Armadillo]

Fluke call it stray ghost voltage;

http://en-us.fluke.com/community/fluke-news-plus/digital-multimeters/stray-ghost-voltages.html

So, I would advise OP to measure with analogue voltmeter having a impedance of about 20Kohm [though fluke uses 3Kohm] or wire a 3kohm resistor in parallel.

But since OP encounter painful shocks, this is not normal and not acceptable. I have not a single smps that exhibits such kind of a problem, no feeling whatsoever.

[amyk]

All this pseudo lawyering amongst almost no suggestions to measure how much current can be drawn...

People have differing levels of sensitivity to current. What may be imperceptible to some could be painful to others. But IIRC up to 300uA may be allowed by the standard.

Search this forum and the Internet for "touch current" for more information.

[Armadillo]

Firstly you determine whether it is "LIVE" or "Ghost" voltage as per fluke document above.

If it is LIVE, don't do any current draw, kind of silly and will damage your meter.

If it is Ghost, the voltage will drop to almost Zero volts, then you can safely proceed to do current draw if your want. It should range from about 90uA to 150uA region.

Can the Y cap be shorted? I don't know. But it's better to be safe.

[mikerj]

You should focus on the subject and context than finding skeletons to reply.

Smartphones are battery operated and even when it is connected to the charger, we don't get a electric shocks [metal case], so your story on the Y-cap cannot be substantiated.

100% incorrect.  Many smart phones will have ~100v AC on the metal case when charging.  The impedance is (or should be) very high, so touching it will cause the voltage to decrease significantly, though some people will be able to feel it (I can).  I thought my original genuine Apple iPhone and iPod chargers were faulty because I could measure similar voltage on the cases and it was unpleasant to touch (not a shock as such, but it felt like the surface was vibrating) but they were all like this.

[Neganur]

Charging an iPhone & listening to music via wired in-ear headphones at the same time can actually hurt quite a bit.

[Armadillo]

You should focus on the subject and context than finding skeletons to reply.

Smartphones are battery operated and even when it is connected to the charger, we don't get a electric shocks [metal case], so your story on the Y-cap cannot be substantiated.

100% incorrect.  Many smart phones will have ~100v AC on the metal case when charging.  The impedance is (or should be) very high, so touching it will cause the voltage to decrease significantly, though some people will be able to feel it (I can).  I thought my original genuine Apple iPhone and iPod chargers were faulty because I could measure similar voltage on the cases and it was unpleasant to touch (not a shock as such, but it felt like the surface was vibrating) but they were all like this.

Make it 110%..... hahahhahahahah 
Bin the phone, might be from china imitation rejects.   

...................... few phone chargers they may be SMPS.  If one of them gave me a shock or even a buzz I would bin it. 

[Armadillo]

Charging an iPhone & listening to music via wired in-ear headphones at the same time can actually hurt quite a bit.

Poor Child. Nowadays you got so many kinds of wield problems, you know, hurt everywhere... and in-ear headphones become conductive due to Y capacitor problems etc..   

[Neganur]

Charging an iPhone & listening to music via wired in-ear headphones at the same time can actually hurt quite a bit.

Poor Child. Nowadays you got so many kinds of wield problems, you know, hurt everywhere... and in-ear headphones become conductive due to Y capacitor problems etc..   

Excuse me, did you run into the door in the morning or something?

[Armadillo]

Thesis KNNB, Anywhere in your reference did it denies the existence of the leakage current.? I would bin the thesis if it would portray such low level of perception ability.

The purpose of the Y cap is to act as a return path to the EMI current caused by poor manufactured uncoupled inductance of the transformer. It suppose to be doing its job especially when loaded. Current flow, voltage drop.
A single value cap selection cannot be expected to meet all tolerances of manufactured transformer.
I am not interested to debate the human perceptible level of leakage current, neither.

If you can feel the bite, bin the product.

It should range from about 90uA to 150uA region.

[Armadillo]

I have NEVER received a shock or even a buzz ...............

[Armadillo]

Devoid yourself from technicality for a moment and revert back to common sense.

You pay not to get bitten, not even a tiny bit.
With that, you set a higher standard for the manufacturers and help improve the level of safety and comfort for the human mankind.
Your level of education is supposed to be different, in the proper direction.

Many don't even feel a buzz. Work on it.

[Armadillo]

I think this is the part you missed.;
the "mandatory" requirement for less than 0.1uF circuit capacitance limit on protective impedance circuit.

And are you against the codes "carefully" researched and written by those professional members of the board? Think about it...."carefully".

BTW, I am interested to know how the headphones become conductive? Are there any conductive parts? I am not a headphones user.

[Armadillo]

Read it, understand it, and if you are not satisfied, you can write to the board to query their intents.

I consider the vibrating sensation normal as it happens at as low as a few tens of uA, and I'm totally fine with it.

You may have the rare anxiety disorder or maybe rare sensitivity ability?, but do check your doc. 

[paulca]

Given the graph presented, which is available from other sources which suggest that pretty low figures can cause muscle contraction, defibrillation and death.

Then given that some standards are allowing leakage current that can be higher than those figures and could potentially in a weaker person, a person with a heart condition or a pace maker cause heart failure one might be scared.

However are we all not forgetting the resistance of the skin is usually measured in mega ohms?  Dry skin circa 100M, wet/broken skin 1M.  If you get shocked by high voltage arc'ing burnt skin becomes much lower resistance down to 500Ohms. 

https://en.wikipedia.org/wiki/Electrical_injury

So while 600mA can kill you, it requires you experience a shock where 600mA actually flows through your body, including the skin resistance and the full resistance through your body to the current exit point.  Then it becomes a matter of ohms law.  It's difficult to get even ball park figures for a complete shock path.  I have seen internal resistance of 600-1000Ohms, but the initial resistance of the skin can be 100 times that.

So worse case of only 600Ohms, you would need V=IR ... V=0.6A * 600Ohm  ... V=360V

That is awfully close to mains voltage.

[amyk]

I am not interested to debate the human perceptible level of leakage current, neither.

Someone who deliberately ignores the facts is not worth arguing with.

Now would the OP please measure the leakage current and tell us...?

[shakalnokturn]

OP has unsubscribed by now, scared of chaos caused by such an innocent question...
He's decided it was less painful getting zapped than trying to follow the answers to his post.

[zetsubou]

OP has unsubscribed by now, scared of chaos caused by such an innocent question...
He's decided it was less painful getting zapped than trying to follow the answers to his post.

  Sorry everyone, I worked 33 hours in the past 2 days and haven't had time to check in.. Looks like I sparked some interest with this post! I appreciate the replies and will get back soon with my results. Happy to open things up if anyone would like a better look. Cheers!

[Armadillo]

Here we see the Armadillo c............

@Shock; That is the worse shameless rubbish I have seen to date, wrecking OP Posting with irrelevances.
I think you must be furious of being deprived the opportunity to self glorifies yourself with someone elses posting, yeah!.
if someone will to graffiti the silly picture with 2 soldering irons in the nose, you know that's an idiot rude lowdown!.. hahahahahaha LOL
I will take you on technically anytime..... other than that I won't be wasting anymore times on rubbish.

[zetsubou]

Some results..









I think it's safe to say this isn't *dangerous* but does it indicate a fault that would cause the sub to produce nearly no sound when turned all the way up?

[Armadillo]

That is definitely a dangerous faulty equipment @180mA leakage current. Not only painful shock, it could have been fatal if the shock persisted for over 1 sec.
You should send it back and demand for compensation on loss and expenses. But how do you exactly go about it, better seek some others views.

[zetsubou]

Can you please confirm if I have my test equipment set properly? Supply to the device is DC, through a transformer. My results AC reading and testing to earth.

[Armadillo]

Your test hookups are proper.
In my opinion, the metal case is supposed to be either doubly insulated Class II or connected to earth, otherwise it will fail the codes. It means you should not be measuring any voltage on the case. Stray Ghost voltage maybe.

There are few situation;

1. The DC power cord may be multi wires and one of them is earth wire which should be connected to the casing. The wire is broken. Or the earth is not true earth [earth broken somewhere else].
2. There is a short circuit in the internal circuit hence you have some problem with the amplifier. The shorts leak to case.
3. Cut exposed wire is touching the metal case.
4. [Append] Faulty power supply.

You should decide "finally" decide if your want to return it or troubleshoot yourself. If you do, I trust a lot of good members here could advise you how to resolve it and repair your amp.
The first thing is seek for any schematic of your amps, just to be sure.   

[shakalnokturn]

That is definitely a dangerous faulty equipment @180mA leakage current. Not only painful shock, it could have been fatal if the shock persisted for over 1 sec. 

Got lost in a coma.... I read 180 micro amperes not mili amperes on that current measurement.



@zetsubou: Your measurements look good.

[Armadillo]

That is definitely a dangerous faulty equipment @180mA leakage current. Not only painful shock, it could have been fatal if the shock persisted for over 1 sec. 

Got lost in a coma.... I read 180 micro amperes not mili amperes on that current measurement.



@zetsubou: Your measurements look good.

Opps!. thanks for point out. Coma yes.

[zetsubou]

Or the earth is not true earth [earth broken somewhere else].

I think this is the most likely issue as the fault shows on the speakers and sub even though they are powered independently..

[zetsubou]

In my opinion you need to return it or at least get them to send out another SMPS, it's not really your job as a consumer to test it however.

Thanks Shock. Unfortunately the unit was purchased a little over 2 years ago. I was in contact with them immediately but ultimately let it go.
Since then, it's sat undisturbed until recently when I reorganised and discovered the issue. I'm afraid I 'own it' 100% 

You've given me an idea though - I'm going to test it on a new GPO. I know the wiring is good at least to the earth junction in the board.

Edit: Same result.

[tooki]

Read it, understand it, and if you are not satisfied, you can write to the board to query their intents.

Steady state 0.5mA may not feel a thing, but if you make contact at peak of AC, there will be a higher instantaneous current that gives you a zap, but if you hold it, you will not feel a thing until you let go of it and grab it again.

I consider the vibrating sensation normal as it happens at as low as a few tens of uA, and I'm totally fine with it.

You may have the rare anxiety disorder or maybe rare sensitivity ability?, but do check your doc.

It's not feeling current through my body. It doesn't feel a thing if I don't move my hand, but if I gently move my back of hands across such a surface, I can feel it's slightly vibrating.

Also, this only works on semi-insulation surface. A fully conductive surface won't work. You can try this on a powder coated microwave, find a dumpster unit with a lot of use (maybe smoke or something has seeped into it, increasing leakage by a bit), cut the ground wire, and measure leakage to ground. It should be in sub mA range, but if you put your back of hands on the powder coated case and swipe on it, you can feel something.

Another case you can try is to find a Macbook before USB-C, and power the charger from a non isolated 220V source without ground, and move the back of your hands on the anodized aluminum surface.

Yep, lots of people notice that on PowerBooks and MacBooks made from aluminum, or indeed even on plastic MacBooks when touching the screws. But indeed, only when using an ungrounded power cord or duck head. (Also, not only on 230V - I noticed it on 120V myself.)

Just as you said, some areas of the skin are much more sensitive, like the back of hands, or the top of your legs (how I first noticed it from screws on a plastic MacBook).

[paulca]

Have you tried touching it with your tongue?

Might be just me, but I have a thing for testing voltages with my tongue.  I can give you a 1 significant figure estimate on a 9V batteries charge with my tongue.   Although this is mains voltage.... so I'd probably not try it.

It's mostly related to how long I feel comfortable with it on my tongue.  If I touch it and instantly recoil, with a lingering pain in the tongue, it's probably near fully charged.  If I can hold it for a second and it leaves a coppery taste but not real pain, it's on it's way out.  If I can hold it constantly, it's a goner.    If there are lots of expletives and spitting it was probably a 12V battery.

[zetsubou]

Have you tried touching it with your tongue?

Hahaha I haven't tried this. If I leave it on my wrist for more than a few seconds, my finger tips start to twitch and start to curl up.
I'm going to move these out to the garage and get a new set.

[Bashstreet]

Have you tried touching it with your tongue?

Might be just me, but I have a thing for testing voltages with my tongue.  I can give you a 1 significant figure estimate on a 9V batteries charge with my tongue.   Although this is mains voltage.... so I'd probably not try it.

It's mostly related to how long I feel comfortable with it on my tongue.  If I touch it and instantly recoil, with a lingering pain in the tongue, it's probably near fully charged.  If I can hold it for a second and it leaves a coppery taste but not real pain, it's on it's way out.  If I can hold it constantly, it's a goner.    If there are lots of expletives and spitting it was probably a 12V battery.

Technically that is a fetish

[stevelup]

If I bought a metal cased device that didn't have an Earth I would point it out to trading standards.  As I understand it, it would not pass British safety standards for mains operated equipment.

Every single bit of kit in my AV rack is metal cased and not one of them is earthed (I'm in the UK too). The only requirement is that it needs to be double insulated.

if I got a mains zap off a metal cased product it would be returned to the vendor with a letter of complaint and a threat of containing trading standards

I think you've been very lucky to never feel this. Perhaps your skin is particularly high resistance... I've lost count of the number of times I've felt this when brushing against the ports on a laptop for example. Interestingly, never felt it on any Apple device.

Some satellite receivers are a nightmare for this with 80 odd volts DC on the LNB connections with reference to ground. It can be a really nasty surprise when you're up the top of a ladder and you touch the grounded dish with one hand and the F-connector with the other...

[Bashstreet]

Hahaha I haven't tried this. If I leave it on my wrist for more than a few seconds, my finger tips start to twitch and start to curl up.

You probably want to see a doctor. Since you've measured 180uA leakage, that amount of current should not cause muscle twitching. You must have a higher sensitivity to electricity, which means otherwise safe devices to other people may hurt you.

Ok please lets stop the bs and nonsense.

Although people perceive electrical current differently "symptoms" of current flowing through body (parts) have same physiological effects.

OP is not "different" or need doctor and my bet is there is higher current leak.

This topic has been full of nonsense stupid advise inaccuracies cock fighting trolling and all sorts.