Earthing (grounding) A Computer In Thailand.

[Brook]

I have a computer at home. I live in an apartment block. When I turn on the computer & I touch the screen I get a shock. It's more of a constant tingle really than a shock. It is much more of a shock when I touch my camera after plugging it in to download photos. I have tired to change to another wall socket & change the multi box I use for all the plugs from the computer to go in to but I still get a shock. I think it must be to do with the earth or grounding? I only have two pin plugs & two pin wall sockets. I possibly may need to earth the computer some how, but I live in a 11 story apartment block. I am on the 7th floor. Can anybody please tell me what I can do? I don't have a UPS. I read that this doesn't necessarily help with this problem anyway.

Thanks,

Brook

[elkangorito]

I have a computer at home. I live in an apartment block. When I turn on the computer & I touch the screen I get a shock. It's more of a constant tingle really than a shock. It is much more of a shock when I touch my camera after plugging it in to download photos. I have tired to change to another wall socket & change the multi box I use for all the plugs from the computer to go in to but I still get a shock. I think it must be to do with the earth or grounding? I only have two pin plugs & two pin wall sockets. I possibly may need to earth the computer some how, but I live in a 11 story apartment block. I am on the 7th floor. Can anybody please tell me what I can do? I don't have a UPS. I read that this doesn't necessarily help with this problem anyway.

Thanks,

Brook

This problem has been discussed at length previously.

You can, if you wish, apply a band-aid, which is in no way a solution to your problem. The band-aid is simply attaching a cable to your computer metal chassis & then running to an earth stake. The earth stake should be about 1.5 metres long minimum & should be made from electrical grade copper. The diameter of the stake should be no less than 10mm. The size of the cable from your computer to the earth stake should be minimum 2.5 millimetres squared. The cable should be clamped to the earth stake & then this connection should be totally covered with an acrylic paint to prevent oxidisation. The stake should be buried directly into the ground so that no more than 300mm protrudes.

But if you wish to solve the problem, you will need to virtually re-wire your home. Also, you will need to install an MEN link. These things must only be done by qualified electrical personnel.

Please understand that any metal clad appliance can electrocute you if the metal cladding is not earthed via a proper wiring system. So it's most likely that you need to earth more than just your computer.

WARNING!!! Do not assume that by attaching a cable to any metallic pipework/framework, you will have a good earth. A good earth can only be achieved by employing the above method.

More information on this thread link below;

Domestic Electrical Wiring

or this website;

http://www.crossy.co.uk/wiring

Edited January 31, 2007 by elkangorito

[Brook]

Thanks very much elkangorito!

But my problem with what you have suggested is that i live in a rented apartment on the 7th floor so wouldnt be able to put a stake in the ground.

Any other options open to me?

Brook

[elkangorito]

Thanks very much elkangorito!

But my problem with what you have suggested is that i live in a rented apartment on the 7th floor so wouldnt be able to put a stake in the ground.

Any other options open to me?

Brook

There are not many options open to you in your situation. The only thing I can think of is to look inside of your Main Distribution Board (breaker box) & see if you can identify an earth wire. God knows what colour it could be. Thais don't seem to follow any standards here. Failing this, I cannot safely advise you on any other method. Sorry.

EDIT: Ensure that you have an earth leakage detection device correctly installed at your breaker box. It should be 30mA @ 20mSeconds maximum. Do not opt for an adjustable unit or a unit with lower trip currents or trip times as this will not necessarily make things safer for you but will probably 'nuisance' trip often.

Edited January 31, 2007 by elkangorito

[Brook]

Thanks very much elkangorito!

But my problem with what you have suggested is that i live in a rented apartment on the 7th floor so wouldnt be able to put a stake in the ground.

Any other options open to me?

Brook

There are not many options open to you in your situation. The only thing I can think of is to look inside of your Main Distribution Board (breaker box) & see if you can identify an earth wire. God knows what colour it could be. Thais don't seem to follow any standards here. Failing this, I cannot safely advise you on any other method. Sorry.

Thanks again elkangorito.

Will have a look at my breaker box tonight, but as you say that may not be straight forward.

Unless anyone else has any ideas guess i am stuck. Would a UPS help? I should have one of these anyway.

Brook

[lingling]

Thanks again elkangorito.

Will have a look at my breaker box tonight, but as you say that may not be straight forward.

Unless anyone else has any ideas guess i am stuck. Would a UPS help? I should have one of these anyway.

A good UPS (with separated circuits) can make it less dangerous, but will probably increase the chance of getting low current shocks as it also relies on grounding and can charge the "ups side" circuit with kVs if not grounded.

As kangorito says, a GFCI is a good start to make sure you won't get any lethal shocks, but the only cure for those little irritating/tickling ones is grounding.

Now, together with a GFCI you can always do "thai grounding". The "thai grounding" will not make it a bit safer (but the GFCI does). The "thai grounding" only gets rid of the tickling but harmless diffs. See the attached pic.

Another alternative is to spend a few baht on a ground cable from your apartment down to ground level if there is no ground available in your breaker box. Most apartments have vertical shafts for pipes etc and you should be able to drop your cable down that. Have a chat with the building management and I am sure they will not have any problem with that.

Edited January 31, 2007 by lingling

[Brook]

Thanks again elkangorito.

Will have a look at my breaker box tonight, but as you say that may not be straight forward.

Unless anyone else has any ideas guess i am stuck. Would a UPS help? I should have one of these anyway.

A good UPS (with separated circuits) can make it less dangerous, but will probably increase the chance of getting low current shocks as it also relies on grounding and can charge the "ups side" circuit with kVs if not grounded.

As kangorito says, a GFCI is a good start to make sure you won't get any lethal shocks, but the only cure for those little irritating/tickling ones is grounding.

Now, together with a GFCI you can always do "thai grounding". The "thai grounding" will not make it a bit safer (but the GFCI does). The "thai grounding" only gets rid of the tickling but harmless diffs. See the attached pic.

Another alternative is to spend a few baht on a ground cable from your apartment down to ground level if there is no ground available in your breaker box. Most apartments have vertical shafts for pipes etc and you should be able to drop your cable down that. Have a chat with the building management and I am sure they will not have any problem with that.

Thanks Iingling.

I dont have too many options really. Will check with my apartment.

Brook

[h90]

I have a computer at home. I live in an apartment block. When I turn on the computer & I touch the screen I get a shock. It's more of a constant tingle really than a shock. It is much more of a shock when I touch my camera after plugging it in to download photos. I have tired to change to another wall socket & change the multi box I use for all the plugs from the computer to go in to but I still get a shock. I think it must be to do with the earth or grounding? I only have two pin plugs & two pin wall sockets. I possibly may need to earth the computer some how, but I live in a 11 story apartment block. I am on the 7th floor. Can anybody please tell me what I can do? I don't have a UPS. I read that this doesn't necessarily help with this problem anyway.

Thanks,

Brook

This problem has been discussed at length previously.

You can, if you wish, apply a band-aid, which is in no way a solution to your problem. The band-aid is simply attaching a cable to your computer metal chassis & then running to an earth stake. The earth stake should be about 1.5 metres long minimum & should be made from electrical grade copper. The diameter of the stake should be no less than 10mm. The size of the cable from your computer to the earth stake should be minimum 2.5 millimetres squared. The cable should be clamped to the earth stake & then this connection should be totally covered with an acrylic paint to prevent oxidisation. The stake should be buried directly into the ground so that no more than 300mm protrudes.

But if you wish to solve the problem, you will need to virtually re-wire your home. Also, you will need to install an MEN link. These things must only be done by qualified electrical personnel.

Please understand that any metal clad appliance can electrocute you if the metal cladding is not earthed via a proper wiring system. So it's most likely that you need to earth more than just your computer.

WARNING!!! Do not assume that by attaching a cable to any metallic pipework/framework, you will have a good earth. A good earth can only be achieved by employing the above method.

More information on this thread link below;

Domestic Electrical Wiring

or this website;

http://www.crossy.co.uk/wiring

well there are other shady solutions which do work, of course. if the tubing is metal, of course connecting to it does help. Got even one report that connecting to a large aluminium window frame (on that wet walls) was enough to get rid of it. But these things may work or not, and might be harmfull if there is an problem in your computer (the next who opens the window die).

Re-wiring the home is usually best done by yourself and NOT by qualified electrical personnel. I had 3 companies here, basically all wanted to cut out the useless earth or connect it with the 0 line, everyone told me the rod in the earth is just useless crap and will not make the lighting working brighter or cheaper......

Point is: very hard to find some professional here in Thailand.

[elkangorito]

well there are other shady solutions which do work, of course. if the tubing is metal, of course connecting to it does help. Got even one report that connecting to a large aluminium window frame (on that wet walls) was enough to get rid of it. But these things may work or not, and might be harmfull if there is an problem in your computer (the next who opens the window die).

Re-wiring the home is usually best done by yourself and NOT by qualified electrical personnel. I had 3 companies here, basically all wanted to cut out the useless earth or connect it with the 0 line, everyone told me the rod in the earth is just useless crap and will not make the lighting working brighter or cheaper......

Point is: very hard to find some professional here in Thailand.

I agree with h90 in that it will be extremely difficult (if not, impossible) to find half decent electricians in Thailand...especially if you, the customer, is not at all familiar with electrical work.

I think it could be an idea that the original poster may like to PM certain people on TV, & discuss 'other' options as to sourcing 'qualified' & professional tradesmen.

[opalhort]

Re-wiring the home is usually best done by yourself and NOT by qualified electrical personnel. I had 3 companies here, basically all wanted to cut out the useless earth or connect it with the 0 line, everyone told me the rod in the earth is just useless crap and will not make the lighting working brighter or cheaper......

Point is: very hard to find some professional here in Thailand.

How true, I have the same experience.

Now our house has been entirely re-wired under my supervision and has been inspected and approved by the MEA.

As for the question in the OP:

A short term solution, albeit risky and only good if he knows what he is doing, would be:

Make sure the Neutral (N) line that enters the apartment block is grounded, usually at the nearest pole or close to the building (one line having a small wire going into the ground). Then replace one of the two pin sockets in the apartment with a three pin one, make 100% sure which is the neutral (N) line and connect this one to the ground pin.

This will get rid of the 'shocks' you get when touching the screen or metal case but it is risky and I believe it to be illegal even here in Thailand. I have done it in the past and it worked, but i knew what I was doing.

opalhort

[elkangorito]

As for the question in the OP:

A short term solution, albeit risky and only good if he knows what he is doing, would be:

Make sure the Neutral (N) line that enters the apartment block is grounded, usually at the nearest pole or close to the building (one line having a small wire going into the ground). Then replace one of the two pin sockets in the apartment with a three pin one, make 100% sure which is the neutral (N) line and connect this one to the ground pin.

This will get rid of the 'shocks' you get when touching the screen or metal case but it is risky and I believe it to be illegal even here in Thailand. I have done it in the past and it worked, but i knew what I was doing.

opalhort

This is extremely dangerous & I would strongly advise against putting anything but an earth conductor, connected to the earth pin in a power outlet. If the neutral is open circuited for any reason, you could end up with a lethal voltage at the earth pin.

And yes, it is illegal in Thailand.

[opalhort]

This is extremely dangerous & I would strongly advise against putting anything but an earth conductor, connected to the earth pin in a power outlet. If the neutral is open circuited for any reason, you could end up with a lethal voltage at the earth pin.

And yes, it is illegal in Thailand.

Yes, you are absolutely correct. This is very dangerous if the N is cut, you can get the full power on the ground pin.

The easiest temporary solution for the OP problem would be to run a single 2.5mm² cable through his window to ground level and tug it into the ground, take the insulation off for at least 50cm. Even without earthing rod it will be better than nothing.

opalhort

[elkangorito]

The easiest temporary solution for the OP problem would be to run a single 2.5mm² cable through his window to ground level and tug it into the ground, take the insulation off for at least 50cm. Even without earthing rod it will be better than nothing.

opalhort

Unfortunately, with electrical safety, there is no room for half measures...particularly when dealing with earthing.

If the OP measured the voltage from an unpainted metallic part of his computer case to a reliable earth point, I reckon he'd see a voltage of between 30 & 90 volts. Anything above 50 volts is considered dangerous due to an increased time before 'letting go'.

If you shove 50 cm of cable into the ground, how long do you think this would last before someone or something interferred with it? Also, it is quite possible that somebody walking near this low quality earth, could be shocked.

In short, run a cable but it needs to be mechanically protected from interferrence from ground level to about the height of 2.3 metres above ground. This can be achieved by passing the cable through PVC or metallic conduit, which is firmly fixed to a wall, from a height of 2.3 M down to ground level. The cable must then be firmly attached to a proper earth stake.

Doing anything other than this could lead to tragedy...especially when dealing with earths.

[Brook]

Thanks for everyone's input.

Not sure if this will mean I can try anything else, but I have a 2 pin plug adaptor which the 3 pin plug from the multi box plugs in to. This 2 pin adaptor has a earth plug coming out from the side. I think this is so you can earth using a wire attached to that pin?

I cant be 100% sure but I think this has only recently happened.

I am going to speak with the apartment today to see if what earthing precautions they have in place & ask them to check in case it has failed?

I have had a computer set up for quite a while now but only in the last few months have I noticed this. Whether this is because I have never plugged a camera in to my computer I don't know, as this was how I found a problem.

[griffer]

er,,,different angle...

try taking the computer to a shop...show them the problem...

i fancy the computer(or maybe the screen) was not originally supplied in this faulty condition.

[elkangorito]

I doubt that the computer shop will or can do anything because most switch mode power supplies tend to have increased leakage with age. Replacing the power supply may solve the problem...until it gets old.

[Brook]

I have read in from other people that have similar problems that they have had problems with getting shocks from other appliances i.e toaster, fridge etc. I only get this from my computer. Is it that computers are more sensitive?

[dvk1951]

There are a lot of suggestions and solutions to you problem but the the bottom line cure is that the computer case needs a path to a properly installed earth, there are no ways around this.

Now, the reason you are constantly getting zapped is because you have become the earth path for the computer chassis earth. This is generally thru your bare feet sitting on a conductive floor or making physical contact with a metal desk or chair at the same time as touching the appliance.

While you are sorting out which of the suggested permenent methods to implement, place a mat or carpet under your feet (rubber compounds are best, like the mats in your car) which will eliminate those pesky shocks until you get a proper fix. Something as simple as wearing shoes can prevent the shocks.

NOTE that this is only a temporary band aid and should never be considered as the final fix. You are not eliminating the source of the electrical leakage, you are only eliminating your body from becoming the path of an electrical circuit.

[elkangorito]

I have read in from other people that have similar problems that they have had problems with getting shocks from other appliances i.e toaster, fridge etc. I only get this from my computer. Is it that computers are more sensitive?

It depends upon;

1. the age of the appliance. The older it is, the more possibility of leakage.

2. the type of insulation. ie double insulated or single insulated.

3. type of appliance. ie electric motors naturally become leakier with age. (fridges etc).

Again, the ONLY way to resolve this situation 'once & for all' & safely, is to have the electrical system properly earthed via the MEN system. There is no other solution. There is no band-aid. There is, however, life & death.

[h90]

er,,,different angle...

try taking the computer to a shop...show them the problem...

i fancy the computer(or maybe the screen) was not originally supplied in this faulty condition.

no thats normal, but don't know why, all my computer showed that effect in my office before I changed office and had a earth cable. They were all arround 60 Volt.

[h90]

I have read in from other people that have similar problems that they have had problems with getting shocks from other appliances i.e toaster, fridge etc. I only get this from my computer. Is it that computers are more sensitive?

It depends upon;

1. the age of the appliance. The older it is, the more possibility of leakage.

2. the type of insulation. ie double insulated or single insulated.

3. type of appliance. ie electric motors naturally become leakier with age. (fridges etc).

Again, the ONLY way to resolve this situation 'once & for all' & safely, is to have the electrical system properly earthed via the MEN system. There is no other solution. There is no band-aid. There is, however, life & death.

Well normaly young healthy no heart problem and you can stay 220 Volt shocks without problem. Just a few people die. As in Thailand this is not a wrong electric installation, it is either bad luck or a punishment for wrongdoings (which might be in the former life).

(who doesn't get it, it is meant sarcastic and indicates that I already mess arround to long with thai technicans)

[lingling]

Well normaly young healthy no heart problem and you can stay 220 Volt shocks without problem. Just a few people die. As in Thailand this is not a wrong electric installation, it is either bad luck or a punishment for wrongdoings (which might be in the former life).

(who doesn't get it, it is meant sarcastic and indicates that I already mess arround to long with thai technicans)

The voltage doesn't matter, it is the current that make a difference. A low current 1MV shock is less dangerous than a unlimited 100V shock. Also, if it don't pass through your heart (finger on a live wire, feet on the ground or one hand on a live wire, the other on something grounded) it is not lethal unless you have a heart condition. Hurts a bit though. Got a few of those...

Also, measuring the voltage between the computer chassis and ground tells nothing as it depends on the internal resistance of your volt meter. A cheap mechanical one will show a lower voltage than a high resistance digital voltmeter for low current leaks.

It may be worth opening up the PSU and blowing out all dust. Remember to unplug it first, and that there will be charged capacitors inside that can give you some nasty shocks. Don't touch anything, just blow out the dust.

Edited February 1, 2007 by lingling

[lopburi3]

There are several things that can be done however. One, as mentioned, make sure you have an operating RCD/GFI device that works (they need to be tested on a regular basis and have buttons for that purpose). Look at refrigerator, water heater, or other appliance, for a ground wire (they may be one that you can attach computer to). Look for a ground wire from air conditioner. Look for exposed rebar that you can attach a ground to (test with multi meter for full voltage reading from hot to this ground). Place rubber or other non conductive mats on floor where you use computer (if you do not present a better path to ground there will be no flow).

In all cases make sure the ground really is ground with a meter check (meters are available for a couple hundred baht at Lotus).

If nothing else possible would highly advise switch to a laptop computer rather than using the desktops that are noted for leakage.

[elkangorito]

The voltage doesn't matter, it is the current that make a difference. A low current 1MV shock is less dangerous than a unlimited 100V shock. Also, if it don't pass through your heart (finger on a live wire, feet on the ground or one hand on a live wire, the other on something grounded) it is not lethal unless you have a heart condition. Hurts a bit though. Got a few of those... The idea that 'voltage doesn't matter' came from persons with little knowledge of electricity, a long time ago. If a human has a resistance of 'K' at any given point in time, then using Ohms' Law, one can easily see that an increase in voltage will result in an increase in current flow through the human. Example;

If V = 100v & R = 20 ohms, then I = 5 amps.

If V = 200v & R = 20 ohms, then I = 10 amps.

If V = 50v & R = 20 ohms, then I = 2.5 amps.

Also, measuring the voltage between the computer chassis and ground tells nothing as it depends on the internal resistance of your volt meter. A cheap mechanical one will show a lower voltage than a high resistance digital voltmeter for low current leaks. Most modern multimeters have a high internal impedance. Any meter, disregarding whether it is digital or analog, is perfectly ok as long as it has an impedance of greater than 500k Ohms.

It may be worth opening up the PSU and blowing out all dust. Remember to unplug it first, and that there will be charged capacitors inside that can give you some nasty shocks. Don't touch anything, just blow out the dust. Good idea.

[tigerbeer]

i looked at where the telephone line comes into the home. and found a wire leading to ground. band aid style. done by the telephone people some time back. then i got the three pin adapter that has an outlet for "earth". bought 5 metres of green wire thick enough and connected the three pin adapter to the phone wiring system which goes to ground. no more shocks. my electrition came by and was amazed at how badly i did the wiring, cleaned it up for me and now can talk on skype without blowing by ears off with shocks!

good luck to the op on getting this issue solved. seems like a lot of help here. what a wonderful forum this is with people from all walks of life and experience to help each other out

[elkangorito]

i looked at where the telephone line comes into the home. and found a wire leading to ground. band aid style. done by the telephone people some time back. then i got the three pin adapter that has an outlet for "earth". bought 5 metres of green wire thick enough and connected the three pin adapter to the phone wiring system which goes to ground. no more shocks. my electrition came by and was amazed at how badly i did the wiring, cleaned it up for me and now can talk on skype without blowing by ears off with shocks!

good luck to the op on getting this issue solved. seems like a lot of help here. what a wonderful forum this is with people from all walks of life and experience to help each other out

It sounds like you've solved your problem but please be careful about connecting 'protective earths' to 'functional earths'. Most communications earth cables are for functional reasons & not for protective reasons. Generally, most standards indicate that functional earths must be seperate from protective earths.

The main thing is that you're no longer getting shocks.

[lingling]

The idea that 'voltage doesn't matter' came from persons with little knowledge of electricity, a long time ago. If a human has a resistance of 'K' at any given point in time, then using Ohms' Law, one can easily see that an increase in voltage will result in an increase in current flow through the human. Example;

If V = 100v & R = 20 ohms, then I = 5 amps.

If V = 200v & R = 20 ohms, then I = 10 amps.

If V = 50v & R = 20 ohms, then I = 2.5 amps.

You are assuming that the chassis is wired to live with no resistance. Most likely, whatever is causing the leak has resistance and therefore the current is restricted by that. Even if you can measure 220V between the chassis and ground, you may not be able to pull more than a milliamp. If that is the case then it is not dangerous but irritating. Until more dust collects and lower the resistance in the leak...

One funny thing to note is that here is a high content of conductive material (metallic particles etc) in the downtown BKK dust. So when some of that collects in computers etc there will be little leak currents here and there causing all kinds of funny side effects so cleaning the inside of your computer every now and then is a good idea. And filtering incoming air is another one...

Most modern multimeters have a high internal impedance. Any meter, disregarding whether it is digital or analog, is perfectly ok as long as it has an impedance of greater than 500k Ohms.

The market here is packed with both bad and good stuff. Some of the analog (mechanical) ones require a decent amount of current flow to work. So yep, invest in a decent digital one.

[elkangorito]

The idea that 'voltage doesn't matter' came from persons with little knowledge of electricity, a long time ago. If a human has a resistance of 'K' at any given point in time, then using Ohms' Law, one can easily see that an increase in voltage will result in an increase in current flow through the human. Example;

If V = 100v & R = 20 ohms, then I = 5 amps.

If V = 200v & R = 20 ohms, then I = 10 amps.

If V = 50v & R = 20 ohms, then I = 2.5 amps.

You are assuming that the chassis is wired to live with no resistance. Most likely, whatever is causing the leak has resistance and therefore the current is restricted by that. Even if you can measure 220V between the chassis and ground, you may not be able to pull more than a milliamp. If that is the case then it is not dangerous but irritating. Until more dust collects and lower the resistance in the leak... Agreed lingling but since the internal resistance/impedance is an uknown factor, I would choose to err on the safe side & assume that the source internal resistance/impedance is low & therefore quite capable of delivering lethal currents.

One funny thing to note is that here is a high content of conductive material (metallic particles etc) in the downtown BKK dust. So when some of that collects in computers etc there will be little leak currents here and there causing all kinds of funny side effects so cleaning the inside of your computer every now and then is a good idea. And filtering incoming air is another one...

Most modern multimeters have a high internal impedance. Any meter, disregarding whether it is digital or analog, is perfectly ok as long as it has an impedance of greater than 500k Ohms.

The market here is packed with both bad and good stuff. Some of the analog (mechanical) ones require a decent amount of current flow to work. So yep, invest in a decent digital one.

[Tywais]

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.

[elkangorito]

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.

Thanks tywais...very interesting.

It sounds like that properly earthing (via the electrical supply) switch-mode supply PC's is essential.

I've noticed a few areas around Pattaya where the PEA has decidedly earthed the neutral at various locations along the power lines. This has only been a recent happening (last 2 months). Maybe they are growing a brain?