Why does my PC keep giving me electric shocks?

[pinkpanther99]

Hi there

I have a PC connected to a UPS. Every time I touch the PC or even the monitor, I get a very small electric shock.

I don't know much about this kind of thing but I figure the problem is probably to do with the electrics in the house, rather than a issue with the PC (although maybe I'm wrong??)

Anyway, how can the problem be fixed and how serious is it?

Thanks

[Crossy]

It's 99% certain the the tingle is because your PC is not properly grounded.

Do you have 3-pin power outlets in the house?

Has someone 'modified' the computer power lead by removing the ground pin?

Are you using a correctly wire 3-pin extension lead?

[bankruatsteve]

And, since connected to UPS, the UPS would also need to carry the ground. You could also try taking off the PC cover and giving the inside a good vacuum.

[jacko45k]

Might just be static.....?

Do you get a single shock or do you get multiple ones every time you touch the PC?

If multiple, sounds like the PC isn't grounded ( I guess it is a desktop not a laptop with a battery).

Try temporarily removing the UPS ...( not necessary with a laptop+battery anyhow)...you need to determine the source of the problem.

[Barin]

I had the same problem in my house as there is no grounding wire in the mains line.

This is not static electricity.

This is caused by the RFI filter in the computer's power supply (2 capacitors connected in series between both wires of the mains AC line with the middle point connected to the metal chassis).

After I have connected the computer's chassis to a small metal rod hammered in the ground this problem disappeared immediately.

[pbassham]

Mine is the same. I guess it would take running new wires for each plug to fix it? Any easier way?

[bangkokheat]

because this is thailand and the electricity is different here

[ggt]

One other thing you might consider...besides the ground...if you are on a concrete floor...you may be acting as a ground while the electricity runs thru you to the concrete...

Concrete is notorious for retaining moisture...you might try placing a rubber mat under your computer area...to shield you from the floor..

[Crossy]

This issue has been discussed ad-infinitum, but no harm in doing it again:-

• Correct solution - Properly grounded 3-pin outlets.
• Preferred alternative solution - Run a wire from the ground pin of the UPS input to a rod bashed into the ground.
• Less preferred alternative solution - Run a wire from a screw on the PC metalwork to a rod bashed into the ground.
• Desperation solution - Run a wire from a screw on the PC metalwork to some structural steel (balcony railings work well).

Note that the balcony railing solution will provide a functional earth and stop the tingle, but it will NOT provide a safety earth to prevent lethal shock in the event of an actual fault.

In any event please ensure you have an RCD/RCBO/Safe-T-Cut device installed in your incoming supply.

[skatewash]

Were you teasing the computer? Normally a computer will never shock a person unless it's provoked.

[ronthai]

As Barin said, most likely your power supply.

If you did not have this before and just started at some time without you making any plug/location changes of your computer, you might also consider that it is time to replace the Power Supply. Depending on your computer power needs, these are available for between 600 to 2500 baht. Most likely for any standard computer a cheaper one will do.

Easily replaced yourself, but if you are uncertain, any Thai computer shop will do it on the spot within 5-10 minutes.

[Crossy]

As Barin said, most likely your power supply.

If you did not have this before and just started at some time without you making any plug/location changes of your computer, you might also consider that it is time to replace the Power Supply. Depending on your computer power needs, these are available for between 600 to 2500 baht. Most likely for any standard computer a cheaper one will do.

Easily replaced yourself, but if you are uncertain, any Thai computer shop will do it on the spot within 5-10 minutes.

Why would one replace a perfectly good power supply??

They all have the front-end EMC filters which cause the tickle when the metalwork is not grounded (as noted by Barin).

Some units are indeed worse than others, in fact reversing a 2-pin plug in the outlet can also reduce (or increase) the tickle.

BUT, the correct (and likely cheapest) solution is to connect the ground.

[malt25]

Were you teasing the computer? Normally a computer will never shock a person unless it's provoked.

Watching porn could be considered shocking by said computer & passing shock onto you.

Just a thought.

[Crossy]

Were you teasing the computer? Normally a computer will never shock a person unless it's provoked.

Watching porn could be considered shocking by said computer & passing shock onto you.

Just a thought.

Ah of course, it's the new tool from the Computer Crimes Bureau to reduce the viewing of 'gentleman's pages', much more effective than the Green Screen of Death

[sabye]

Cheapest method is to just wear a pair of flip flops to prevent the power from going through the computer then you and then to good old mother earth. I have the same problem even with a properly grounded 3 pin system. So much humidity living on the ocean front that we all just use flip flops or put a mat under the our feet to prevent shock. But the correct solution is to earth all of your receptacles. Another alternative I have found here is to go to your local hardware store and pick up 2 prong plug that you can put a 3 prong plug into. It has an addittional connection that you can hook an earthed wire to.

[Crossy]

Yup ^^^, one of these:-

[Rjmi]

Had the same problem with a house in Kanchanaburi - shocks from PC, microwave and the fuse box. The local sparky said to stand on a towel when using said appliances which didn't inspire confidence in this risk-shy Brit.

My Thai wife didn't seem overly bothered until I found a proper sparky who found that some Dibert had wired the ground into a neutral in a power socket in the house.

The consequences could have been deadly so suggest you get a proper check done on all the electrics. Sooner safe than sorry...

[joespnet]

Does the presence of a whole house Safe-T-Cut solve the grounding problem even if the outlets are ungrounded 2-prong outlets, or do you need both?
What if the house already has a Safe-T-Cut, and this mild tingling shock is still felt on the chassis of a laptop?

This issue has been discussed ad-infinitum, but no harm in doing it again:-

• Correct solution - Properly grounded 3-pin outlets.
• Preferred alternative solution - Run a wire from the ground pin of the UPS input to a rod bashed into the ground.
• Less preferred alternative solution - Run a wire from a screw on the PC metalwork to a rod bashed into the ground.
• Desperation solution - Run a wire from a screw on the PC metalwork to some structural steel (balcony railings work well).

Note that the balcony railing solution will provide a functional earth and stop the tingle, but it will NOT provide a safety earth to prevent lethal shock in the event of an actual fault.

In any event please ensure you have an RCD/RCBO/Safe-T-Cut device installed in your incoming supply.

[Crossy]

The amount of current from the tingle is very small, nowhere near enough to trigger your Safe-T-Cut. It is not in itself hazardous to life and safely leaks to earth when even a poor ground is provided, the Safe-T-Cut will not prevent the tingle.

Your Safe-T-Cut will significantly reduce the chances of you dying in the event that you get hold of a live wire or an un-earthed Class-1 appliance with a L-E fault.

Class-1 appliances (desktop PCs, washing machines, water heaters) need to be correctly grounded even when you have a Safe-T-Cut type device.

[meltingpot2015]

Static Electricity...Is that like Microsoft Works.

[gandalf12]

Ground the UPS that is the mostly likely source of the problem

[Tywais]

It is not static electricity. I posted the answer the 1st time in 2005 and a technical detail of it in 2007. I'll just post my original tech detail here.

For those interested in the technical reasons the PC is hot.

This drawing of the emi/rfi filter front end of nearly all PC power supplies shows the two filter capacitors connected to each side of the line and common to earth ground (chassis). It is simply a voltage divider if the chassis is floating and the chassis will be around 110 volts relative to neutral, which at some point will be earth - back at the pole (assuming 220VAC in). The cap values are usually between 2nF and 4.7nF which works out at 50Hz 1.6Mohms and 677kohms respectively. This is then 68uA and 162uA respectively the current limit from the filters.

PE on the diagram is the Earth ground pin to the power supply and also the computer chassis.

So around 100 microamps, that is 100 millionths of an amp will tingle but not dangerous. It would require a current several hundred times that to be an issue physically.

What I did to fix it at my previous house. Used a sealed hole where the termite people came and drilled, put a ground rod in the hole and attached to the adapter similar to what Crossy showed above.

[Crossy]

Thanks Tywais, the advice was good in 2005 it still works in 2015

I even nicked the image for my 'help my house only has 2 pin outlets' page here http://www.crossy.co.uk/wiring/2pin.html

[Tywais]

Thanks Tywais, the advice was good in 2005 it still works in 2015

I even nicked the image for my 'help my house only has 2 pin outlets' page here http://www.crossy.co.uk/wiring/2pin.html

I couldn't remember where I stored my original ground pin image so had to nick my image back off your site.

[Crossy]

Touché

[hawksway]

Standard wiring in Thailand is 2 wire positive/negative. Most Europeans if building from scratch will use three wire plugs and sockets - the additional wire being for earth. If you have desktop PC unearthed then just get an additional wire, screw it to the chassis of the PC passing it through a hole in the wall to the outside and attach it to a small length of rod. Bury it as deep into the soil where it will stay reasonably moist. I did that with my old house and no more shocks. The shocks you are getting are not dangerous on standard computers which use 5V and 3v circuits.

DENNIS

[12DrinkMore]

And, since connected to UPS, the UPS would also need to carry the ground. You could also try taking off the PC cover and giving the inside a good vacuum.

Sure, that will definitely hoover up all those nasty excess electrons that have collected in the case. .

Maybe an extra fan is needed to simply blow them out?

[12DrinkMore]

Standard wiring in Thailand is 2 wire positive/negative. Most Europeans if building from scratch will use three wire plugs and sockets - the additional wire being for earth. If you have desktop PC unearthed then just get an additional wire, screw it to the chassis of the PC passing it through a hole in the wall to the outside and attach it to a small length of rod. Bury it as deep into the soil where it will stay reasonably moist. I did that with my old house and no more shocks. The shocks you are getting are not dangerous on standard computers which use 5V and 3v circuits.

DENNIS

With all respect,

even if the solution works, indeed it has already been mentioned a few times above, maybe it is better to avoid posting advice on a topic that is not your area of expertise?

1. 2 wire positive/negative

No, it is AC live and neutral, not DC positive and negative.

2. The shocks you are getting are not dangerous on standard computers which use 5V and 3v circuits.

No, they use 3.3V, 5V but most of the power is supplied by 12V rails.

BUT the mains input voltage is the standard 220V (yeah this is Thailand), so this voltage also exists within the case.

The shocks could be dangerous if there was short in the power supply unit.

[gandalf12]

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Standard wiring in Thailand is 2 wire positive/negative. Most Europeans if building from scratch will use three wire plugs and sockets - the additional wire being for earth. If you have desktop PC unearthed then just get an additional wire, screw it to the chassis of the PC passing it through a hole in the wall to the outside and attach it to a small length of rod. Bury it as deep into the soil where it will stay reasonably moist. I did that with my old house and no more shocks. The shocks you are getting are not dangerous on standard computers which use 5V and 3v circuits.

DENNIS

With all respect,

even if the solution works, indeed it has already been mentioned a few times above, maybe it is better to avoid posting advice on a topic that is not your area of expertise?

1. 2 wire positive/negative

No, it is AC live and neutral, not DC positive and negative.

2. The shocks you are getting are not dangerous on standard computers which use 5V and 3v circuits.

No, they use 3.3V, 5V but most of the power is supplied by 12V rails.

BUT the mains input voltage is the standard 220V (yeah this is Thailand), so this voltage also exists within the case.

The shocks could be dangerous if there was short in the power supply unit.

Some sense at last in an otherwise topic of guesses

[meltingpot2015]

Many of the posters playing - hazard a guess