Case electrified, Grounding problem?

[pakotlar]

Hey guys, I was wondering if you could help me. Recently, I was working on my computer, and when I tried to open the case, or touched the frame (not on parts where it is painted) I could a fairly serious electric shock. Clearly my case isn't grounded, but I've looked for any exposed wires that may be touching my case, and taped up anything that I think may be causing the problem. It doesn't always happen. My computer works fine though.

The only thing that could be suspect in my eyes, is a fairly shoddy 7v hack job that I did on one of my cables for a fan (not coming from PSU). The wire was exposed until I electric taped it, but the connection is shoddy, so if I move the cable too much the fan will rev up full speed. I have a normal 3pin-molex connected to another fans 7v modded molex, and that is connected to the PSU molex. Could that be causing an issue? Also, how can my computer be working normally if the case is electrified. I feel this could be a serious issue, but I can't find any solutions via usual googling.

PS: I've used this setup at home, and never had an issue. It may have happened once, but I think its because one of the smaller power cables was touching the case. It was resolved. I moved into a new apartment with pretty shitty electric wiring, and we've had grounding problems in the apartment before (my roomate got shocked turning of his overhead light by metal string). If anyone could help that would be great. I'm a bit worried.

If anyone could help I would be really grateful

 

[Boke]

I would suspect that it is the outlet that your plugging in to that is the problem.
The Hot and Neutral wires are probably switched, possibly the ground too if it has one.

"Also, how can my computer be working normally if the case is electrified. I feel this could be a serious issue, but I can't find any solutions via usual googling."

The wires carry alternating current but the white one is grounded to earth already and is also grounded to your case. So touching it will not harm you as it is already grounded.

If the wires are switched your computer will generally run fine because it is still getting the alternating current it needs. But the black wire (the Hot) is now connected to your case and if touch the case you become the ground...

Get one of these and test the outlet. You can pick one up just about anywhere->
http://www.globaltestsupply.com/test_equipment/AEMC_OT-1_Outlet_Tester_.cfm

 

[Zaphod]

Do you have a TV card in that PC? In my experience a common cause of getting a shock from a computer is that it's hooked up to a cable system with a fault somewhere. Thus, the electrical earth may be transferred to the TV cable resulting in shocks. In addition, this can be a serious fire hazard. A galvanic isolator on the antenna outlet will fix it if this is the problem in your case.

 

[pakotlar]

Thanks guys, I will try switching the outlet. I was just unplugging my RJ-45 connector from the ethernet port and could barely do it because every time i touched the case my fingers convulsed lol. My right hand hurts lol.