Electric Shocks From Computer Equipment

[manarak]

I frequently get electric shocks from my computer equipment in Thailand.

Everything seems to have voltage: computer case, all cables (even VGA)...

My older laptop has a decorative metallic-paint edge, and even that stings sometimes.

I guess this comes from power plugs missing a proper ground.

I am worried about damage being done to the components.

Is there a way to hinder the buildup of voltage in computers?

Are there power supplies that can provide ground without being connected to ground themselves?

Edited January 31, 2013 by manarak

[Crossy]

You need to ground your metalwork, even a poor ground will suffice to stop the shocks.

Whilst annoying, these shocks which come via the mains inlet filters in the PSU are unlikely to be harmful to yourself although they may cause issues for interconnected kit particularly kit which is properly grounded. Such a situation cost my company a lot of money on a project in Seoul when another contractor connected his equipment to ours via a serial cable, we had a ground, he did not and our expensive Stargate serial card paid with its life

Almost any metal which is connected to your building fabric will be good enough for a functional ground, water pipes and balcony railings are favourite if you can't get a proper rod in.

IMPORTANT NOTE. These makeshift grounds are functional grounds not safety grounds, they will NOT protect you from a potentially fatal shock in the event of an internal fault between live and ground. Please ensure you have RCD (earth leakage) protection on your electrical installation.

[manarak]

Thanks for the tip!

I think the easiest solution will be to get the wall plug grounded, since all my equipment supports grounding through power supply.

I guess there are no devices (such as UPS) able to provide ground if they are themselves not properly grounded, right?

Edited January 31, 2013 by manarak

[lopburi3]

It needs to be grounded (whatever it is) - many homes now have grounds but most of the cheap outlet box connection cords are just two wire even when the outlets are grounded type and you lose your ground when using them so be sure that is not the problem.

[Crossy]

Actually, getting the outlet grounded may be easier said than done, are you in a house or a condo?

No, I'm afraid you can't pull a ground out of the air, at least not one that will stop you getting the tingles, ground has to be connected to, well, ground

EDIT Good point L3, watch out for those 3-pin extensions that aren't.

[manarak]

Actually, getting the outlet grounded may be easier said than done, are you in a house or a condo?

No, I'm afraid you can't pull a ground out of the air, at least not one that will stop you getting the tingles, ground has to be connected to, well, ground

EDIT Good point L3, watch out for those 3-pin extensions that aren't.

Condo, but ground floor with nothing underneath. That might be my luck, driving a rod into the ground might solve my situation if I don't find a third wire under the 2 plug outlet or some big metal plumbery.

Edited January 31, 2013 by manarak

[cooked]

When I first moved here I wondered why there were wires coming through the walls attached to rusty nails stuck in the ground under the roof. I realised that somebody had done an earthing job. I now have a safe-t-cut circuit breaker installed but still get an enlivening tingle when I touch metal bits of the computer or stuff connected via USB.

[Crossy]

If you're ground floor do you have a bit of garden outside where you can drive a rod?

[manarak]

If you're ground floor do you have a bit of garden outside where you can drive a rod?

mee loei :-)

[ignis]

Don't go about barefooted....... you make the ground, so put rubber between you and floor, so what you touch is not grounding it. even flip flops. or those 49 baht rubber slip ones

Edited January 31, 2013 by ignis

[Para]

I've had it before on 2 pin plugs when the live and neutral have been reversed in the wiring. Quick test is to turn the AC plug so you swap pins.

[transam]

If two pin on PC, attach a wire to a chassis screw and fit a three pin plug for the now three wires. If no earth sockets drill a hole in the floor and bash in a rod. If your floors up then inform your heighbours underneath.

[JetsetBkk]

Home Pro extension sockets appear to be properly connected inside.

The earth goes to all earth pins, the live and neutral are round the right way and the switch operates on the live wire.

They are now sold under the "Elektra" brand, but were sold under the "HomeBase" brand.

.

[puyaidon]

I had a problem very similar but I had been using a very good UPS. The computer expert I contacted who built the machine said that I had a short in the main board from a previous electric surge before I bought the UPS. We then replaced the main board for that reason and some other reasons. The shocks stopped.

There are other ways for the case to put out shocks so look for more than just the ground and UPS.

Edited January 31, 2013 by puyaidon

[Crossy]

I had a problem very similar but I had been using a very good UPS. The computer expert I contacted who built the machine said that I had a short in the main board from a previous electric surge before I bought the UPS. We then replaced the main board for that reason and some other reasons. The shocks stopped.

There are other ways for the case to put out shocks so look for more than just the ground and UPS.

With respect to your 'computer engineer' there is no way that a 'short on the main board' can cause the casework to become live, particularly if it is properly grounded in the first place.

Exposed metalwork MUST be grounded unless the equipment is Class-II (which most desktop PCs are not).

By far the most common reason for PC metalwork to tingle is lack of a ground, the tickle comes from leakage via the mains inlet filter (which leak in normal operation), a ground, even a poor one, will take away the itch.

[Cloggie]

Turn the plug will sometimes help.

[JakeBKK]

I had a problem very similar but I had been using a very good UPS. The computer expert I contacted who built the machine said that I had a short in the main board from a previous electric surge before I bought the UPS. We then replaced the main board for that reason and some other reasons. The shocks stopped.

There are other ways for the case to put out shocks so look for more than just the ground and UPS.

With respect to your 'computer engineer' there is no way that a 'short on the main board' can cause the casework to become live, particularly if it is properly grounded in the first place.

Exposed metalwork MUST be grounded unless the equipment is Class-II (which most desktop PCs are not).

By far the most common reason for PC metalwork to tingle is lack of a ground, the tickle comes from leakage via the mains inlet filter (which leak in normal operation), a ground, even a poor one, will take away the itch.

I strongly agree with your post. To make you feel an electric shock on exposed metal parts you are usually between 85 and 110 v ( according to my multimeter) while your power supply delivers +/-5 and +/- 12 v to your mainboard. Anything over 18 v on the board and you'll see your capacitors smoking.

Edited February 1, 2013 by JakeBKK

[JakeBKK]

Turn the plug will sometimes help.

Hey Mr Westinghouse, we have an alternating (around 45 - 60 Hz) current nowadays.

Edited February 1, 2013 by JakeBKK

[Crossy]

Turn the plug will sometimes help.

Hey Mr Westinghouse, we have an alternating (around 45 - 60 Hz) current nowadays.

Actually, reversing the polarity can sometimes reduce the potential on an un-grounded PC casework. It depends upon the exact architecture of the mains inlet filter relative to the live (220V) and neutral (near ground) conductors.

Of course, it has an equal chance of increasing the level of shock received.

The common symmetrical mains filters make an ungrounded case float at around 50% of mains potential (110V or thereabouts), the source impedance is high so even a poor ground will kill it dead.

Note the two 1nF capacitors from the supply to the ground line, it's these that are responsible for the tingle.

[ignis]

If not earthed you get the same from anything,

For me was always Pumps in the pond, put your hand in, step into my ponds you got a electric tingle, many of the pumps have no earth wire

1st few time about 10 years ago found out which pumps and took one of them back,

Now a day no problem as have a rubber mat to stand on.. same with PC, fixed that earth wire had/was not connected....... saying that you can find in many places here rubber backed mats people use at there PC desk

What I use outside, here you buy in a pack of squares and click together to make what ever size you want....... also have in from of washing machine [also 2 pin]

PC rubber mats come in many sizes, colours, even with carpet on top., you could of course just use a big flat car mat as sold in supermarkets, Many Supermarkets also sell the PC desk floor mats.

[electau]

Earth the computer, it will resolve your problem. Install a RCBO on the power circuit supplying the computer.This will give additional protection against an earth fault.

There are minor leakage currents that are causing the problem.

[wpcoe]

After living in Thailand for a dozen years and experiencing the "computer tingle" every time I touched a metal piece, last year I grounded the outlet in my living room where it all plugs in. Instantly, of course, no more tingles. But now, probably six months (?) later, every time I touch the case, I brace myself for a tingle/shock. Old habits die hard.

By all means, find a way to ground the outlet. Do be a slug like me and wait 12 years.

[bobl]

Do be a slug like me and wait 12 years.

I'm going to assume you meant "don't"...

For me, 1 year and I'm still 'thinking' about it. And I live in a bungalow where digging an earth pit, driving in some rods and running a wire into the house would be a 1 hour job (not counting however long it would take me to find a store with earth rods and some cable)... Last time I 'thought' about it, not having a drill to make a hole in the outside wall to pass the new cable, was enough to get my ass back on the sofa... Maybe tomorrow...

[Tywais]

The common symmetrical mains filters make an ungrounded case float at around 50% of mains potential (110V or thereabouts), the source impedance is high so even a poor ground will kill it dead.

Note the two 1nF capacitors from the supply to the ground line, it's these that are responsible for the tingle.

And to be technically specific on that particular diagram the impedance of the cap at 50Hz is 3183098 ohms which is around 36 microamps maximum current to the body. Now if the cap shorts out without a ground, that's a different story.

[twix38]

Not read above so sorry if mentioned.

I had similar problems. I switched my computer off via electric in-line socket on/off switch where all plugs pluged into. However, I left them plugged in and and assumed as power switch was off it wasn't a problem. Electricity was still getting through and giving me static shocks from the build up, so replace socket and/or actually unplug all devices after turned off. Good luck

Edited February 3, 2013 by twix38

[h90]

You need to ground your metalwork, even a poor ground will suffice to stop the shocks.

Whilst annoying, these shocks which come via the mains inlet filters in the PSU are unlikely to be harmful to yourself although they may cause issues for interconnected kit particularly kit which is properly grounded. Such a situation cost my company a lot of money on a project in Seoul when another contractor connected his equipment to ours via a serial cable, we had a ground, he did not and our expensive Stargate serial card paid with its life

Almost any metal which is connected to your building fabric will be good enough for a functional ground, water pipes and balcony railings are favourite if you can't get a proper rod in.

IMPORTANT NOTE. These makeshift grounds are functional grounds not safety grounds, they will NOT protect you from a potentially fatal shock in the event of an internal fault between live and ground. Please ensure you have RCD (earth leakage) protection on your electrical installation.

two things to mention:

Either ground everything or nothing. I had the same situation as you and it cost me 100.000 Baht. Important is also that connected electronic is on the same ground. Else it may happen that someone cut one ground by mistake and that equipment ground itself over serial port, USB, VGA etc etc what is usually not so good.

these makeshift grounds have the disadvantage that in case of an problem the balcony railing may has 220 Volt.....

[h90]

Turn the plug will sometimes help.

Hey Mr Westinghouse, we have an alternating (around 45 - 60 Hz) current nowadays.

Actually, reversing the polarity can sometimes reduce the potential on an un-grounded PC casework. It depends upon the exact architecture of the mains inlet filter relative to the live (220V) and neutral (near ground) conductors.

Of course, it has an equal chance of increasing the level of shock received.

The common symmetrical mains filters make an ungrounded case float at around 50% of mains potential (110V or thereabouts), the source impedance is high so even a poor ground will kill it dead.

Note the two 1nF capacitors from the supply to the ground line, it's these that are responsible for the tingle.

To add, often a lot voltage can come over the "neutral" line. And if someone connected neutral with ground (what was common a few decades ago), but the wire to the ground rod does not exist anymore you may get a lot of funny effects....

[Crossy]

Actually a N-E link (MEN or PME) is a requirement on all new installations. The neutral is held at or very near ground potential, it's actually loss of the neutral which is the potential hazard in these installations.

Systems with large neutral potentials are invariably overloaded TT systems.

This page shows the various earthing systems in use http://en.wikipedia.org/wiki/Earthing_system

As to the balcony rail becoming live. If you have a L-E fault in your PC and no RCD then yes, all the metalwork will potentially become hot rather than just your PC although every balcony rail I've tested have actually had a pretty low impedance to ground. I did note that it provides a functional not safety earth.

[Daffy D]

Do be a slug like me and wait 12 years.

I'm going to assume you meant "don't"...

For me, 1 year and I'm still 'thinking' about it. And I live in a bungalow where digging an earth pit, driving in some rods and running a wire into the house would be a 1 hour job (not counting however long it would take me to find a store with earth rods and some cable)... Last time I 'thought' about it, not having a drill to make a hole in the outside wall to pass the new cable, was enough to get my ass back on the sofa... Maybe tomorrow...

You need to think this through a bit more.

You don't need to dig any pit, just hammer the rod in the ground.

The wire would be thin enough to pass trough between the window and the frame so no need for any hole drilling.

See the job already half done. A few more days thinking on the sofa and you can probably reduce the workload even more

[bobl]

Do be a slug like me and wait 12 years.

I'm going to assume you meant "don't"...

For me, 1 year and I'm still 'thinking' about it. And I live in a bungalow where digging an earth pit, driving in some rods and running a wire into the house would be a 1 hour job (not counting however long it would take me to find a store with earth rods and some cable)... Last time I 'thought' about it, not having a drill to make a hole in the outside wall to pass the new cable, was enough to get my ass back on the sofa... Maybe tomorrow...

You need to think this through a bit more.

You don't need to dig any pit, just hammer the rod in the ground.

The wire would be thin enough to pass trough between the window and the frame so no need for any hole drilling.

See the job already half done. A few more days thinking on the sofa and you can probably reduce the workload even more

SSSHHH!!!

I was thinking pit & 3 rods, and a 6mm cable... Old habits die hard, worked on contracts that demanded a max 1 ohm earth resistance...

Getting an earth to the fusebox is only half the battle. Whole house is wired with black&white cable, not twin&earth, that appears to be buried in the walls (no conduit), and all the sockets are 2 pin - so getting the earth to the sockets (and changing to 3 pin sockets) is a far bigger challenge than getting the earth...

Back to catching up with Spartacus...