Electrical Earth In Thai Room?

[Crossy]

All building materials such as concrete and block work etc are electrically conductive.

What kind of crazy talk is this?

Actually, they are mildly conductive, if they weren't you wouldn't get a shock when you touched the live wire.

That said, I'm not convinced they are sufficiently conductive to trip a protective device, certainly not an MCB. They may have enough leakage to prevent the tingle often felt from un-grounded IT equipment.

Tests are required.

[electau]

The method of earthing as mentioned is widely used in domestic installations in Thailand and one could say that it is policy not legislation. In many cases it is not practicable to install a compliant earthing system. The method of earthing to a stud or dynabolt may be acceptable under the circumstances. It will limit touch voltages to an accepable level but it of course will not be designed to carry a fault current to trip a MCB.

An RCD should always be installed.

In 2008 I purchased a new refrigerator/freezer for my wife it was a Sanyo and was fitted with a two core flex and 2 pin (flat blade) plug top. The instructions (in Thai) with a diagram showed the connection to be made if earthing was required. This consisted of a short length of 1.00mm flexible green earthing conductor attached to a screw on the rear of the unit and the attached to a stud or bolt near to the floor level. This would appear to meet Thai requirements and was supplied by the manufacturer.

With reference to the fact that building materials are conductive. Concrete will conduct electrical current and is generally in contact with the general mass of earth. It would conduct enough current to operate a RCB in most situations and would minimise the value of touch voltage due to the effect of equipotential bonding. If you can bond to a section of rebar or metallic piping in contact with the general mass of earth all for the good.

Of course if one can install a complaint earthing electrode do so by all means but realise that there are alternative arrangements. You may be living in a condo, townhouse or shophouse situation and not own the property.

Remember one is in Thailand not in Australia/NZ or a Western European country and some leeway must be applied to suit the circumstances.

　

　

　

　

　

　

　

　

[InterestedObserver]

The National Electrical Code (NEC) in the US does not permit installing two prong receptacles in new construction, has not for at least 25 years. A proper grounding electrode system is required for all structures to which the NEC applies. You cannot purchase a major home appliance that does not come with a 3-prong grounded plug. Anything with a 2-prong plug will have double insulation. Sort of leaves out the dynabolt appliance ground.

[longball53098]

Sorry this is not the USA or Europe or Oz. The standards here are something altogether different. If anyone chooses to build their house here and wants the place powered based on a standard in place in another country that's you're choice but don't expect the local sparky to be aware of the standard you want. You will be lucky to get something to the "Thai" standard if there is such a thing.

So does this cancel out the dynabolt idea? If someone can produce a written regulation as to how to earth homes and apartments and appliances maybe we would know what the accepted standard is? And as mentioned it's possible the bolt method could meet some test as acceptable. But without a test I would be very leery of this method of earthing.

I personally would not use this method but it does not mean it is not approved in the regs somewhere. Without seeing the OPs place I would not even venture a guess on what's possible to resolve this.

[elkangorito]

Until someone can produce them, there are no Standards for domestic installations in Thailand. Standards are legislated & not 'suggestions' from some engineering institute. Nor is information issued by an energy authority (PEA/MEA), a Standard.

The latest & most relevant info comes from a PEA booklet, which I had translated. The booklet & the translated meaning can be viewed at this thread:

Unfortunately, there are many ambiguous points in this booklet, which contradict the reality of the PEA Thai electrical system. An example is the large number of IT installations throughout the PEA area, whilst the booklet gives the impression of TT/TN connected systems.

Notwithstanding any of this, earthing by any means other than a copper electrode of appropriate length connected to a copper wire of appropriate size, which then connects to the Main Earth bar within a switchboard, is not reliable.

This is all about 'knowns' & not the utterly variable condition of cement (what ratio mix is it?etc etc).

I consider such information as 'Use a bolt in a nearby tile/cement floor' etc to be dangerous. The knowns are not only obvious about copper but can easily be found &/or calculated. Dealing with variable 'unknowns', tested by measurement devices or not, is relying upon an 'unproven' situation.

Do I need to go into 'step & touch' voltages, which can be created by a high impedance earth?

I guess I could just let this go & leave Crossy to deal with the mess created by people posting potentially dangerous info but I won't in this case.

To summarise:

1] There are no known domestic installation Standards in Thailand to date.

2] The tried & tested methods to earth an installation DO NOT incorporate the use of bolts etc in cement &/or tiles.

3] Almost all of the installations in my local area are IT. I am yet to find a TT connected system in Thailand. I doubt that I will find a TT connected system in my local area.

[bankruatsteve]

"Earth" is just a relative zero potential to A/C voltage. It doesn't HAVE to be earth - just anything that can sink. There is nothing dangerous you can do in attempts to ground. Anything is better than nothing. And it doesn't matter what kind of "system" there is. ALL systems eventually have a neutral based to "ground" and whether it's IT/TT/MEN or whatever doesn't really make that much diff.

[elkangorito]

I think you had better check your FACTS steve. Then again, you do like to use yourself as earth when measuring voltages with your multimeter, don't you.

I kept this pic that you previously posted as an example of what NOT to do.

Edited July 6, 2010 by elkangorito

[bankruatsteve]

Not going there Elk. I stand on what I said. You or anyone else cares to dispute, the discussion should be interesting. OK? The facts and the physics probably won't change though.

[elkangorito]

The facts and the physics probably won't change though.

You're correct about that.

The 100 years or so of electrical engineering facts are still working & currently advise against such things as using cement &/or tiles for a reliable earth. This, as a matter of fact, is legislated in many countries. The Laws of Physics do not exclude Thailand. The methods have been 'tried & tested' for a very long time in many countries.

[bankruatsteve]

The facts and the physics probably won't change though.

You're correct about that.

The 100 years or so of electrical engineering facts are still working & currently advise against such things as using cement &/or tiles for a reliable earth. This, as a matter of fact, is legislated in many countries. The Laws of Physics do not exclude Thailand. The methods have been 'tried & tested' for a very long time in many countries.

OK. To repeat, what I said was anything is better than nothing for grounding. Codes are established to provide best practice. If the only way to establish gournd connection is through a 2.5 meter copper rod buried in the earth, then one should not have to worry about standing barefoot on a tile floor 2 stories above the ground. But, that IS a worry b/c just about everything is conductive to some degree and, in this topic - if all the other good suggestions are not available or too costly, then YES connecting the ground wire to any available construction is better than nothing - and NOT dangerous.

[electau]

I would like it to be made very clear that this method of earthing should only be used as a last resort in Thailand and where it is not practicable to install a compliant earthing system or access to a earth electrode is not possible.

If one was to carry out a resistance test from the general mass of earth to a concrete wall or floor within a building one will find that it will be less than 10K ohms (10000 ohms) which is within the operating parameters of an RCD.

The earth in this case minimises the effects of minor electrical shocks caused by leakage currents due to equipotential bonding effect.

In the event of an earth fault the protective device in this case an RCD will disconnect the supply in less than 0.04secs which would comply with AS3000 and IEC requirements.

It would not of course trip an MCB that is why a RCD is used.

To carry out the resistance test use of a insulation tester on the 250V range. Do not use a VOM.

Remember if the protective earth fails on an item of electrical equipment the RCD will operate.

The current path will be via the human body and though the conductive building materials to the general mass of earth.

[elkangorito]

Anybody who wishes to follow the advice, "Any earth is better than none", needs to realise a few things.

1] 'Earths' need to be tested by appropriate means, in order to varify functionality & therefore safety.

2] Known 'conductors' (metals) are usually chosen for such a situation because they are reliable if installed correctly.

3] Normal cement &/or ceramics (tiles) are not considered to be 'conductors', even though they may conduct electricity.

4] If a high impedance earth exists, 'step & touch' voltages may be present, which may be hazardous/lethal.

5] Since normal cement & ceramics are not 'conductors' as such & the installation of such may vary, they cannot be compared to conductive materials (metals) in any way. Nor may their impedance remain constant over time, again compared to 'conductive' materials.

6] The reason why most 'professionals' would never advocate the use of normal cement &/or ceramics for an earth connection has everything to with the above points & therefore with 'duty of care'.

Go ahead & save a few Baht by listening to those who advocate the use of 'non-conductive' materials as an earth. In the meantime, I strongly advise against this potentially dangerous practice.

Again, over 100 years of practice advocates 'metals' to be used as 'earths'. Copper, Aluminium, 17% (chrome) stainless steel & galvanised steel are the only acceptable earthing materials according to the huge body called the IEC (with the exception of some other metals as well).

There is always a way to achieve an effective & reliable earth. This may not be cheap in a few cases but there is no need whatsoever to die for the sake of some extra expense.

[bankruatsteve]

You keep saying that I "advocate" unsafe/unreliable methods. I have not. So I really wish you would stop saying that.

In attempt to make this discussion interestiong though...

What is it about "high impedance" that you find potentially lethal? "Earth" is not high empedance. If it was, then there would be no electron transfer and nothing would work. And, if there is high impedance between you and a live A/C wire then there is no step touch or other voltage potential to worry about. Explain what you find dangerous about this situation.

The root problem (for this topic) is that many (most?) construction in Thailand does NOT provide reliable ground to the consumer. So, what do you do when there is no other option available (as many presented previously)? ARe you saying that if you can't do something according to code, then do nothing??

Actually, I'm guessing that a screw in the wall probably isn't all that bad. Crossy, have you had a chance to do some testing?

[Artisi]

It is very likely that the "screw in the wall" especially in Thai bathrooms which are never water-proofed meaning the walls and floors are more than likely continually damp/wet MAY by a devious route via concrete re-bar etc to the outside surrounding ground and be a potential earth point - but never in my house.

Edited July 7, 2010 by Artisi

[electau]

Anyone who has studied the electrical distribution system and electrical installation practices in Thailand would realise that :

1. Two (2) pin socket outlets are in widespread use in all electrical installations.

2. There is no policy of earthing.

3. Three (3) pin socket outlets where installed may not have the earth terminal earthed.

4. Earthing where carried out is to minimise the effects of minor touch voltages that may be received by indirect contact. This is in effect a form of equipotential bonding.

5. Adaptor plugs are available to convert a 2 pin socket to 3 pin.

The problem arises with the 2 pin socket outlet. ( One may add here that two countries never had the problem with 2 pin socket outlets as 3 pin were made mandatory from the outset, they were Australia and New Zealand. The UK, European Countries, US, and Japan for examples had 2 pin socket outlets, 3 pin socket outlets where a later development. So even these countries had problems with earthing).

Thai practice of earthing is very often to just connect an earth conductor as stated, in other words to the floor or if available a section of metalwork. They regard that this is satisfactory as far as they are concerned.

However this is not designed to carry fault current of any magnitude but it will carry excessive leakage current which will trip an RCD. However in many cases an RCD is not installed.

Touch voltages. Where the touch voltage exceeds 50VAC in normal areas and 25VAC in wet or damp areas disconnection MUST occur in less than 0.04secs. Using an RCD achieves this result. (IEC 61200-413)

The RCD is the protective device for earth fault protection.

Fault currents may well be minimised in practice due to the distribution neutral conductor not being earthed and the main neutral not being earthed at the consumers electrical installation. (IT).

　

　

[bankruatsteve]

Yah - and let's not forget that the OP just wants to ground his <deleted> REFRIGERATOR in an apt building that has no earthing system. however, some of the replies have diverted to requirements and concerns for earthing a transformer or a CU.

For example, Elk mentions "high impedance earth" as a potention lethal problem. In retrospect, I will assume he meant high impedance earth FAULT. In absence of an earth system, I wonder where such a fault will occur? Certainly not from a refrigerator grounding wire. And, I can't even imagine a scenerio where a fridge on tile would create lethal step voltage (ff any at all).

In this case, it's the touch voltage that COULD be a concern. And I'll say it again, for a REFRIGERATOR, screwing the ground into the wall is better than nothing and probably even better than attaching to an unknown earthing system (where high impedance earth faults would be a concern).

That's it for me.

Cheers

[Crossy]

OK as promised I've done some tests with potential grounds around my apartment.

IMPORTANT. These results are from MY home, yours may be different, it must not be implied that because mine is good yours will be too. YMMV!!!

Tests performed using the earth loop impedance function of my Robin KTS 1630 Advanced Digital Multi Function Meter http://www.bis.fm/products/Robin_KTS1630.asp I admit my tester is out of calibration (didn't get it done before getting it shipped from the UK, sorry).

Potential grounds, all in my 10th floor apartment in an older block:-

My real ground provided by the supply company :- 0.5 ohms (likely MEN connected, but can't confirm, link is not in my distribution board)

Incoming water pipe (galvanised) :- 1.1 ohms

Steel balcony railing :- 1.2 ohms (after removing multiple layers of paint)

13mm rawlbolt in brick wall (it's been there some time holding up the outdoor unit of an aircon, outdoor unit is sat on wood blocks so is isolated) :- no result, tester would not even acknowledge that this was grounded and so would not perform a test.

Aluminium window frame :- greater than 2k ohms (over range), but tester did at least acknowledge that this was grounded.

Metal shelves sitting on the concrete balcony :- greater than 2k ohms (over range), but tester did at least acknowledge that this was grounded.

I also tested a 2m copper ground rod (at a different location and in wet earth) :- 5 ohms.

I'll let you draw your own conclusions about the efficiency of the various potential grounds.

[Deke]

Have a look inside your breaker panel. If your apartment is reasonably new construction the chances are good that there is a ground connection there. Whoever wired the rooms might just have put in two-wire outlets and not brought out the ground. I've run into this many times here.

[bankruatsteve]

OK as promised I've done some tests with potential grounds around my apartment.

IMPORTANT. These results are from MY home, yours may be different, it must not be implied that because mine is good yours will be too. YMMV!!!

Tests performed using the earth loop impedance function of my Robin KTS 1630 Advanced Digital Multi Function Meter http://www.bis.fm/pr...bin_KTS1630.asp I admit my tester is out of calibration (didn't get it done before getting it shipped from the UK, sorry).

Potential grounds, all in my 10th floor apartment in an older block:-

My real ground provided by the supply company :- 0.5 ohms (likely MEN connected, but can't confirm, link is not in my distribution board)

Incoming water pipe (galvanised) :- 1.1 ohms

Steel balcony railing :- 1.2 ohms (after removing multiple layers of paint)

13mm rawlbolt in brick wall (it's been there some time holding up the outdoor unit of an aircon, outdoor unit is sat on wood blocks so is isolated) :- no result, tester would not even acknowledge that this was grounded and so would not perform a test.

Aluminium window frame :- greater than 2k ohms (over range), but tester did at least acknowledge that this was grounded.

Metal shelves sitting on the concrete balcony :- greater than 2k ohms (over range), but tester did at least acknowledge that this was grounded.

I also tested a 2m copper ground rod (at a different location and in wet earth) :- 5 ohms.

I'll let you draw your own conclusions about the efficiency of the various potential grounds.

Not sure I would draw any conclusions. But, this is interesting. Why, do you think, you get a reading on windows and shelves but not the wall that holds them?

[thaibeachlovers]

Have a look inside your breaker panel. If your apartment is reasonably new construction the chances are good that there is a ground connection there. Whoever wired the rooms might just have put in two-wire outlets and not brought out the ground. I've run into this many times here.

Nope, it's an old room in the Thai part of Pattaya, not a flash new farang condo. No way I'm touching that switchboard with exposed live wires!

Thanks for all the discussion.

I drilled a hole in the wall, and stuck in a dynabolt. Should be sufficient for the warrenty.

PS I've never seen a wiring system with EVERYTHING going through ONE fuze before!

[InterestedObserver]

<snip>

Potential grounds, all in my 10th floor apartment in an older block:-

My real ground provided by the supply company :- 0.5 ohms (likely MEN connected, but can't confirm, link is not in my distribution board)

Incoming water pipe (galvanised) :- 1.1 ohms

Steel balcony railing :- 1.2 ohms (after removing multiple layers of paint)

<snip>

With these ohmic values I hardly think the loop includes the earth mass, most likely the neutral completes the circuit back to the power source. From the 10th floor I assume you used a Loop Impedance Tester not an Earth Resistance Tester.

Edited July 8, 2010 by InterestedObserver

[Crossy]

With these ohmic values I hardly think the loop includes the earth mass, most likely the neutral completes the circuit back to the power source. From the 10th floor I assume you used a Loop Impedance Tester not an Earth Resistance Tester.

Indeed. I strongly suspect that there is a properly installed ground mat somewhere too, the complex has its own sub-station.

Yes, those are loop-impedance tests (which is the determining factor as to whether the protective device operates). I do have the kit to check earth resistance, but I've never used it as the UK regs don't require anything more than a loop test, and as you rightly say, it's a bit difficult from the 10th floor.

As to why I couldn't get a reading from the Rawlbolt, I really don't know, I was expecting a similar result to the window. It's in a brick wall, quite high up and well protected from damp whereas the window frame is exposed to the weather so I suppose that could be a factor.

Either way there is no way I'd use the frame or bolt as a ground, the railing or water pipe would be adequate if an RCD was installed.

[electau]

And this is what the original post was all about, basic protection only.

The earth as described will divert any standing leakage current. It is the RCD that is the protective device. ( if installed ).

Touch voltage area is 1 metre in the horizontal plane and 2.5 metres in the vertical plane from the point where a person is standing at floor level.

The RCBOs available ( Safe-T-Cut ) have adjustable sensitivity 5/10/20/30ma and an operating time of less that 0.4secs.

And this is what will be found in most residential Thai electrical installations.

　And with regard to the test instrument use the 250 volt range on an insulation tester this will give you the approx value of the conductive material, do the test on a section of wall or floor with the probes about 1 metre apart.

　

[electau]

Here is a prime example of a Thai electrical installation.

1 x 2 pole MCB as a main isolator.

3 x 2 pole MCBs to protect final subcircuits.

2 pin TIS socket outlets as standard.

No main earth or earth electrode.

What would you do to provide additional electrical protection?

[Crossy]

Here is a prime example of a Thai electrical installation.

1 x 2 pole MCB as a main isolator.

3 x 2 pole MCBs to protect final subcircuits.

2 pin TIS socket outlets as standard.

No main earth or earth electrode.

What would you do to provide additional electrical protection?

OK, I'll bite.

First and foremost an RCD device, this would provide shock protection whilst the other work is carried out. Do note that an RCD, being an electromechanical device, can fail and should not be relied upon as the only protection (but it's way better than nothing).

Then, if practical install a single earth electrode connected to the ground bar in the distribution board and replace the 2 pin outlets with 3 pin with the ground pin connected to our nice new ground. If the ground stake is not possible a connection to structural steel or a metal water supply pipe may be adequate (but testing should be performed). Even if it is decided not to replace the outlets (because all connected devices are Class 2), any water heaters should be properly grounded.

Finally, if implemented in the distribution system, a PME/MEN link between the incoming neutral (on the hot side of the RCD) and the ground bar.

RCDs, grounded outlets and PME/MEN are all apparently now part of the 'regulations' for new installations, but I've never managed to locate said regulations for a domestic installation apart from in the PEA pamphlet referenced in other posts which has some worrying inconsistencies.

Then, TEST THE INSTALLATION with a proper installation tester.

EDIT and go around replacing all the twist and tape joints with proper connectors

EDIT 2 and throw away all those fake 3 pin extension cords, you know, the ones with 3 pin outlets but only a 2 wire cable.

[electau]

The installation has been in use for many years and has been well maintained. The distribution system uses an unearthed neutral.

1. Install an RCBO. This would give earth fault protection and would trip in less than 0.4 secs.

2. Then at later date consider upgrading the electrical installation to the current standard but only if it was warranted.

And I think you will find that this is what most Thai electrical contractors would do.

　

　

[David006]

Wow... this thread has taken on a life of it's own and has certainly prompted many techies and others to further thought...

being a bit of the same persuasion, I thought I would throw this over the wall:

... I asked my one time co worker, an IEEE member, "...what HE thought would be the implications of a "dynabolt" earth or ground."..

....his response, though guarded (typically P.Eng ..lol), was that in some cases there could be a possibility that a direct short to ground by any appliance so "grounded" may well raise the potential of your habitation to at or near domestic voltages which may result in an exciting time doing the dishes in a stainless sink or taking a shower. He noted that this may occur if the "dynabolt" ground was more than 5 ohms. He emphasized that the best solution is always a a GFI/RCD which must use neutral as return leg ...never ground.

so here you have it, another opinion to the mix....

[gotlost]

It SHOULD be grounded but it doesn't have to be to work. Just screw the ground wire into the floor then. After all that's what you will be standing on if anything (which probably won't) does create a fault.

screw the ground onto a tiled floor? eh?

dont think that will work too well

Thais love this one. I see it all over Thailand.

[Crossy]

And I think you will find that this is what most Thai electrical contractors would do.

But that's not what you asked, you asked what WE would do

We are all entitled to our opinions as to what is safe and what is unsafe, you have yours, you know mine

As a minimum, any home I and my loved ones inhabit will have a quality RCD/RCBO and 3 pin outlets with ground if any Class 1 devices are to be used (since we have PCs, irons and cooking appliances which are Class 1 all outlets will be grounded).

Whether the grounding used is IT, TT, TN-S or TN-C-S (useful link http://en.wikipedia.org/wiki/Earthing_system ) with or without MEN/PME depends entirely upon the system that's been implemented by the supply authority. If in doubt assume TT as it would provide adequate protection in all cases when combined with an RCD.

Here endeth my involvement with this thread apart from normal moderating duties

[thaibeachlovers]

Had a shock from a wire when the copper became exposed and it has made me a bit freaked ( no earths in the room ) so I'd like to put one of those safety cutouts onto the plug to which most of our appliances are attached. Common at "home", but can't find one here, even at HomePro. I'm referring to the plug in sort, not a "wired in" one.

Anyone know where I can find one? I'm in Pattaya to be specific, but if I had to, could go to Bangkok.

Thanks.