Hardware USB Electric Shocks

[Jiehfeng]

I know for a fact that if electrical equipment isn't grounded properly, there will be an excess of electricity in any of the metal areas of those components. Touch a metal part and you can feel a strong electrical current which you aren't supposed to feel. A lot of power strips, especially Chinese made ones I've noticed don't come with proper grounding. So any electrical component you connect to it gets an excessive electrical charge in any metal area you touch, and it spreads all over (for example a PC, where you touch the back of the metal I/O or any metal casing, you get the shocks).

So my power outlet is properly grounded, I got it done by an electrician, other components are working fine without this excessive charge I am speaking of. But my Printer in particular has this charge coming out of the USB wire (from the printer which is powered to the properly grounded outlet, to the A connector supposed to plug into the PC). It gives a huge amount of charge, and my tester lights up when I put it on the USB A end. I am afraid of using the printer this way, as when I connect it to the PC, the whole PC has that excessive charge.

Any ideas where the issue lies? The power cable of the printer maybe? What exactly should I do?

 

[Jayro]

I'd return the printer, so it won't fry your expensive PC. The cable too.

 

[Jiehfeng]

I'd return the printer, so it won't fry your expensive PC. The cable too.

It's not that a major problem, it's something to do with grounding I'm sure. Returning it right now is too drastic of a decision, and not to mention I can't lol, it's been a while since I had it.

 

[FAST6191]

For a lot of USB chargers they have a noise filter capacitor across the primary and secondary of the circuit. While capacitors are not normally thought of as resistive devices they do have some and thus they do pass almost full mains voltage onto the circuit, the current is usually so small that you won't feel it unless you put your lip on it or something. If you do though then you may feel a high voltage tingle. Some of the incredibly cheap and nasty power supplies do also have more dangerous aspects so be sure it is not that.

Also "I know for a fact that if electrical equipment isn't grounded properly, there will be an excess of electricity in any of the metal areas of those components." may or may not be complete bollocks depending upon what you mean.
Electricity needs a path to flow, this is true (no monopoles here). If you have a lead to a high potential and you leave it sitting in the air there will be no flow (unless it is silly high voltage and enough to cause a spark to the ground but enough of that one). When you connect it to the a lower potential in that same circuit then current will flow.
If you yourself provide a better path for that circuit then instead a portion of the current will go through you which is not usually considered good. This is why most things are contained in boxes/cases so as to prevent that. If the case features some metal that could become live (say if a wire broke inside the case and touched it from the inside) then said case will hopefully be connected to the earth pin which provides a better path to ground than the person that maybe touches it (humans are pretty conductive but copper is better) and thus still not pose a problem.
What can also happen is if your neutral connection is not good (entirely possible with the rather suspect US plug and socket design, common also if things arc out inside the socket and corrode things or cover them in soot) that you might provide a better path but again cases exist for a reason and should not be live.
If you touch a metal case thing and get a continuous electrical feeling (as opposed to discharging some static or something) and it is not the simple tingle of a USB/switch mode supply then something has gone wrong. If you have a bad connection to neutral then the device should just not work, touching a case should have no bearing on this and nothing should happen when you do.

The reason for three pins on plugs is so one can be the "earth" pin, some also call this a ground but that can confuse matters as ground can have different meanings in different types of circuits (if I am wiring a vehicle then ground means something, though it could be positive or negative ground depending upon the age of the vehicle). Depending upon your safety devices (the UK favours something called an RCD, the US typically goes for something called a GFI) then if all the current does not return along the neutral wire, typically because someone stuck their hand on a live part and did the providing a better current bit or because the part which was connected to earth started conducting, it will disconnect the power. In an ideal world the earth will never conduct anything but as it is not an ideal world it is added. Also a lot of sockets in the US are wired incorrectly but that is a matter for another day.

 

[Jiehfeng]

For a lot of USB chargers they have a noise filter capacitor across the primary and secondary of the circuit. While capacitors are not normally thought of as resistive devices they do have some and thus they do pass almost full mains voltage onto the circuit, the current is usually so small that you won't feel it unless you put your lip on it or something. If you do though then you may feel a high voltage tingle. Some of the incredibly cheap and nasty power supplies do also have more dangerous aspects so be sure it is not that.

Also "I know for a fact that if electrical equipment isn't grounded properly, there will be an excess of electricity in any of the metal areas of those components." may or may not be complete bollocks depending upon what you mean.
Electricity needs a path to flow, this is true (no monopoles here). If you have a lead to a high potential and you leave it sitting in the air there will be no flow (unless it is silly high voltage and enough to cause a spark to the ground but enough of that one). When you connect it to the a lower potential in that same circuit then current will flow.
If you yourself provide a better path for that circuit then instead a portion of the current will go through you which is not usually considered good. This is why most things are contained in boxes/cases so as to prevent that. If the case features some metal that could become live (say if a wire broke inside the case and touched it from the inside) then said case will hopefully be connected to the earth pin which provides a better path to ground than the person that maybe touches it (humans are pretty conductive but copper is better) and thus still not pose a problem.
What can also happen is if your neutral connection is not good (entirely possible with the rather suspect US plug and socket design, common also if things arc out inside the socket and corrode things or cover them in soot) that you might provide a better path but again cases exist for a reason and should not be live.
If you touch a metal case thing and get a continuous electrical feeling (as opposed to discharging some static or something) and it is not the simple tingle of a USB/switch mode supply then something has gone wrong. If you have a bad connection to neutral then the device should just not work, touching a case should have no bearing on this and nothing should happen when you do.

The reason for three pins on plugs is so one can be the "earth" pin, some also call this a ground but that can confuse matters as ground can have different meanings in different types of circuits (if I am wiring a vehicle then ground means something, though it could be positive or negative ground depending upon the age of the vehicle). Depending upon your safety devices (the UK favours something called an RCD, the US typically goes for something called a GFI) then if all the current does not return along the neutral wire, typically because someone stuck their hand on a live part and did the providing a better current bit or because the part which was connected to earth started conducting, it will disconnect the power. In an ideal world the earth will never conduct anything but as it is not an ideal world it is added. Also a lot of sockets in the US are wired incorrectly but that is a matter for another day.

Very informative, thanks. To put it simply, I can touch all the other USB A metal connector parts of the other devices connected to my PC when unplugged, and they do not give me a constant electrical charge feeling, if not at all. When I put a tester to it (the screwdriver thing with the lightbulb in it), it doesn't light up one bit. But this printer's USB A in particular gives a constant electrical charge to my fingers, it's not so powerful as to spread throughout the hand, but it's enough to be very prominent in the fingers. And the tester's lightbulb lights up pretty brightly when connected onto it. So when I plug in this printer USB cable to my PC, either at the back of the motherboard or the front panel, then if I touch any metal casing in the PC, I get that same constant electrical charge feeling to my fingers, and it goes immediately when I unplug the USB wire.

I'll try switching the printer's power cable from one outlet to another and see if that helps, but I'm at a loss of what I should do here.