i have read quite a lot about this and i would like the experts opinion. I have an old dell desktop with a 250 watt PSU - PSU is grounded to the metal casing of the psu and the psu in turn touches the metal part of the PC case. I brought the PC from UK to Vietnam to be donated to a home. I noticed that since i am in Vietnam, the case is live / if i touch it, i get a tickle and if i apply a test pen, the test pen lights up. I also noticed that most wall outlets are not earth at all (most sockets only have the live and neutral. 1. Is it safe for me to use the PC (even though users touching it will get a tickle. 2. Do you that the capacitors are faulty (the ones leaking current to the body? (They are blue Thank you Michael
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4\$\begingroup\$ Possible duplicate of Why a high voltage AC always present in SMPS AC to DC power adapters \$\endgroup\$– Voltage Spike ♦Commented Aug 10, 2017 at 4:01
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2\$\begingroup\$ It is normal to get 200uA of AC leakage from Y caps in the line filter. The spec is 250uA. Make an earth ground to avoid the tingle. \$\endgroup\$– D.A.S.Commented Aug 10, 2017 at 4:35
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Short answer, anything with a metal case that is not double insulated should be grounded for safety. A live to earth short circuit fault inside the computer will create a life threatening condition. Make sure the supply is fused and install a ground rod connected to the supply outlets ground connections.
I experienced exactly this condition in Portugal which is supposed to have European standards on electrical installations. I was getting a tingle from the metal screens on the speakers of an old laptop. As has been pointed out this is low current and not harmful itself. It is however a warning that all is not safe with the electrical installation.
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\$\begingroup\$ Absolutely : the quality of the installation... \$\endgroup\$ Commented Aug 10, 2017 at 8:19
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\$\begingroup\$ Two remarks: Laptops often have the C-type EU plug (no earth) they will have the "tingle" you describe. This is not a failure. If a live to chassis short would ever occur you would most likely not die, since the RCD (GFCI) will save the day. \$\endgroup\$– Jeroen3Commented Aug 10, 2017 at 9:44
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\$\begingroup\$ Yeah this should not apply to a laptop smps, the tingle thing with a high voltage (very low current) may be detectable, but most laptop supplies are double insulated and designed for international use. However, in the OPs case, it does not sound feasible to add a ground rod, for a donated PC? It may be easier and cheaper to source a suitable atx supply locally if the UK one is behaving unsafely with the Vietnamese system? (not saying a ground rod is a bad idea, just overkill for a single device surely) \$\endgroup\$ Commented Aug 10, 2017 at 10:54
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\$\begingroup\$ @Jeroen3 A RCD is a good idea but is a bit of an assumption for an installation that is not even grounded properly. \$\endgroup\$– RoyCCommented Aug 10, 2017 at 11:18
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\$\begingroup\$ Thank you for the answers. The PSU is grounded. When i opened the psu, i noticed 2 ceramic capacitors (blue) connecting the live and neutral to the earth/metal body of the psu chassis. The power from the socket has no earth - i also noticed that none of the sockets have a earth pin, so effectively there is no earth in the wiring of the house. Not sure how this works. Do you think it is safe to use the pc - PC by the way boots up fine and works great. Just the tingling sensation i get if i touch the metal chasis at the back of the PC. \$\endgroup\$ Commented Aug 10, 2017 at 12:38