# Slight shock from computer USB port



## Cool Comps (Oct 9, 2011)

Guys!!!!!!!

Suddenly I realised yesterday my USB ports are giving me a slight shock if i touch them.
Now today i am getting the shock anywhere i touch the metal portions of the case!!
What should i do?


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## pulkitpopli2004 (Oct 9, 2011)

its a common problem.. get the earthing done in your room.. call any electrician...


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## pimpom (Oct 9, 2011)

Check your earthing. In 99.9% of cases, this is not due to any defect in the system, but due to normal leakage in the PSU, UPS and spike guard.

The PSU etc have built-in filters against voltage spikes and EMI. These filters provide slight leakage paths to the cabinet metal which is supposed to be connected to ground. If the system is properly grounded, the leakage currents flow harmlessly to ground (earth) via the house wiring.

The problem is that the wiring in many buildings don't have proper earth lines. Therefore, when you touch any metallic part of the system, the leakage currents flow through your body and gives you a shock.

If your body is dry, the shock is mild and normally not dangerous. But if your body is damp, e.g. when you're sweating or if you've just finished having a bath, then your body's electrical resistance is much lower and the shock can be very unpleasant or even dangerous.

The solution is to have a properly grounded wiring.


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## Tarun (Oct 9, 2011)

^^^^^^+1 it earthing problem or check ur main CPU connector which is connected to ur mains and the PSU sometime it due to the wire


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## Cool Comps (Oct 9, 2011)

BTW My Cabinet stands on a wooden platform. Can it be that the leakage isnt being transferred?

Also, I dont know whther its an earthing issue. But i found out that if i switch on the socket and then the UPS, a green led glows on my Mobo. And already there is shock on my case. Any further ideas. Yes ill be calling my electricin. However if he says that electric ports aare fine, will he be able to point out the problem or will i have to point it out myself(or call an engineer)


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## coderunknown (Oct 9, 2011)

Cool Comps said:


> BTW My Cabinet stands on a wooden platform.



read pimpom's post once more. its about the earthing. not where your cabby is kept. it may happen if the earthing wire is broken to that particular socket or the earthing was not done properly when the electrical work was carried out.


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## casual_gamer (Oct 9, 2011)

In my case, if i touch the metallic portion wearing a slipper, i won't get any shock, but with bare foot i get shock. what does this mean? If it was a earthing problem i should get shock even while wearing slippers, right?


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## Faun (Oct 9, 2011)

casual_gamer said:


> In my case, if i touch the metallic portion wearing a slipper, i won't get any shock, but with bare foot i get shock. what does this mean? If it was a earthing problem i should get shock even while wearing slippers, right?



Ever wonder why birds perching on high tension cables do not die out of shock ?



Spoiler



because they wear slippers made of dry/non-ionized air


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## guru_urug (Oct 9, 2011)

@OP

Do this:
1) Try using another spikeguard and check if prob is gone
If you dont have another spikeguard then directly connect the PSU power cable to the wall socket, power on the CPU and check if there is still any voltage leakage (preferably with multimeter). If the problem is no more, then culprit is spikeguard, get a new one!
2) Incase there still is, then try using another wallsocket (preferably of another room. Check if the problem goes. If it does, culprit is the earthing in your room
3) If possible get another PSU from a friend and start your PC with it and check if the problem goes. If it does then culprit is PSU, get a new one!
If problem still persists then there is only one possibilty, the earthing in your house is faulty, call an electrician and get the problem fixed ASAP


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## pimpom (Oct 9, 2011)

This issue has come up several times before, so I prepared the drawing below a few years ago to illustrate how it works, but I never got around to uploading it until now. I hope it will help.

@casual_gamer: Look at the picture. See how the leakage current flows through your body and out to ground through your feet. If you're wearing rubber slippers, they block the flow of current. But this is only if your slippers are good electrical insulators and are dry.

*img265.imageshack.us/img265/1508/leakage.png


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## s18000rpm (Oct 9, 2011)

Do you have any Chinese or local make speaker system or similar stuff connected to your PC?

Remove all such connections and check.

I once had similar problem, only diff was my PC was transferring 240 volts to USB Ports, CRT monitor (shock on glass).
I thought there could have been earthing issue, our psu gone wrong, I checked up earthing, bought a new psu cooler master, but still got the shocks, then finally removed a local make 5.1 system connection, that bloody thing was leading current into the PC via 3.5mm cables.


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## asingh (Oct 9, 2011)

@Pimpom:
Really nice.


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## Cool Comps (Oct 10, 2011)

The problem turned out to be with my spike buster. One of the earthing pins on it was loose so at times it was cutting off the earthing. My electrician told me that. I had another Spike buster(which i had bought from MD when i bought my rig but i hadnt used it). So i started using it. I also kept his tester. ANd There isnt any shock now. 

BTW Can Your keyboard or mouse also shock you? Coz i feel a slight buzz in my fingers at times when using them. Now this can be my imagination or it can be since its quite late int he night. But just wanted to know.


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## d6bmg (Oct 10, 2011)

@pimpom: nicely explained with pic. 
+1 rep.


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## pimpom (Oct 10, 2011)

Cool Comps said:


> BTW Can Your keyboard or mouse also shock you? Coz i feel a slight buzz in my fingers at times when using them. Now this can be my imagination or it can be since its quite late int he night. But just wanted to know.


Have you been having wet weather? Moisture on the mouse and keyboard can allow enough current to flow on them to give a slight tingling or buzz, especially if they are not perfectly clean. The accumulated dust and dirt absorbs moisture from the air. Even if the plastic surfaces look dry and reasonably clean, microscopic amounts of dust and moisture can get trapped there.

Also remember that no material is a perfect insulator. The plastic body of your keyboard and mouse can pass tiny amounts of current. Normally, such currents are too small to be felt. But they may be noticeable under certain conditions. Another factor is that different people have different levels of sensitivity.


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## jerrin_ss5 (Oct 10, 2011)

very good explanation pimpom
i may sound naive but please help me as i am weak in electricals
but orange is ac and black i presume is ground so the leakage current should go through black wire na


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## s18000rpm (Oct 10, 2011)

Cool  said:
			
		

> BTW Can Your keyboard or mouse also shock you? Coz i feel a slight buzz in my fingers at times when using them. Now this can be my imagination or it can be since its quite late int he night. But just wanted to know.



That's earthing problem. Get the sockets checked again. Buy a Belkin spike buster.


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## rsk11584 (Oct 10, 2011)

most common assumption is earthing must be faulty first call electrician or take a multimeter and check earthing at socket if it is fine then something is wrong with the appliance, even in my house we have weird problem when the heater is swithched off sometimes in bathroom i get shock,  called electrician and he checked earthing , heater etc and all is fine, now the shock is coming only morning during -6.30 to 07.00 am for some 10-15 mins  not at all times so electrician told that someone must be using some faulty appliance, then had to tell neighbours about ti and guess the stupid neighbour stopped using his faulty appliance, probably an IRON ,,, but still electricity is hard to understand inspite of fauly appliance earthing should go via earth to ground and not shock the person,, dont know im not engineer tap in bathroom gave strong shock, and i am even today afraid but since electrician checked n certified strong earthing i need to only worry about neighbours, if the shock that ur getting is only sometimes and repeats only at specific times then it might be due to some faulty appliance used by somenoe in ur home


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## vamsi_krishna (Oct 10, 2011)

Brings back the memories of my old days. There were times, where, I was afraid to even go near my cabinet. 

Anyway.. as the other members are pointing it out, it is clearly the grounding problem. Make sure that the socket is properly grounded. You will be good to go.


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## abhidev (Oct 10, 2011)

try using a 3-pin plug if you are using 2-pin plug...


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## casual_gamer (Oct 10, 2011)

is it okay for the computer hardware if earthing is not done? i have ups and spike guard, will my hardware get damaged?


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## Cool Comps (Oct 10, 2011)

My earthng is fine. And I tested using tester on my keyboard. And after the elctrician came i havent even got a shock form my keyboard. So i assume it was my imagination of my fingers getting buzzed by the keyboard and mouse. HAHA LOL


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