Idiots

[Crossy]

I found this useful article on the IEE website (it's freely available to the public).

2005_16_autumn_wiring_matters_earthing_your_questions_answered.pdf

Although it refers to PME (that's British for MEN) it clearly shows the different supply architectures used.

Also note that in the UK the link N - E is provided in the service head before the kWH meter and is totally inaccessible to the user, meaning that even if L - N are inadvertently reversed at the meter E is still E and not something approaching phase voltage.

One of my pet worries with the use of MEN in Thailand is that it's not resistant to twonks like those in the OP getting it wrong!

[CDNinKS]

One of my pet worries with the use of MEN in Thailand is that it's not resistant to twonks like those in the OP getting it wrong!

Yes, and if I understand this correctly even if I choose not to go with MEN, but my neighbor does and the idiots reverse it at the meter, then I go live right?

[Crossy]

One of my pet worries with the use of MEN in Thailand is that it's not resistant to twonks like those in the OP getting it wrong!

Yes, and if I understand this correctly even if I choose not to go with MEN, but my neighbor does and the idiots reverse it at the meter, then I go live right?

There is certainly a danger if you have any common metalwork with your neighbour, metal water pipe, handrails etc even structural steel could cause a problem.

If you're not actually physically attached to the other house there's not likely to be an issue.

[bankruatsteve]

One of my pet worries with the use of MEN in Thailand is that it's not resistant to twonks like those in the OP getting it wrong!

Yes, and if I understand this correctly even if I choose not to go with MEN, but my neighbor does and the idiots reverse it at the meter, then I go live right?

There is certainly a danger if you have any common metalwork with your neighbour, metal water pipe, handrails etc even structural steel could cause a problem.

If you're not actually physically attached to the other house there's not likely to be an issue.

OK - I'm not trying to step on anybody's toes or to raise emotions, but this "idiots reverse it at the meter" thing is NOT a problem and I really get annoyed when people cast off Thai's as idiots.

I submit that:

1 - If you do have a properly grounded system (I won't go into how that is done b/c it's already been stated many times before), it is NOT POSSIBLE to reverse the leads and somehow make the neutral live. And I defy anyone to prove it is.

2 - If you have an ungrounded system, like most upcountry places do, I suppose the leads could be crossed at the meter, but it wouldn't make a twit of difference b/c IT DOESN'T MAKE ANY DIFFERENCE. ie: there is no A/C device that knows or cares which lead is neutral or hot. OK - there is but only to manage some components so that it doesn't make a difference.

3 - In my opinion, the Thai electric system, grid, whatever - is very well serviced and maintained even with comparison to the states or Europe. That is not being done by "idiots".

4 - I also agree with most, that Thai electrical standards are either lax or not being enforced for new housing. But, I have seen good standards applied in new major constuction at least in Bangkok.

Cheers

[manarak]

I am sure you are not from Germany, France, Switzerland or austria :-)

3 - In my opinion, the Thai electric system, grid, whatever - is very well serviced and maintained even with comparison to the states or Europe. That is not being done by "idiots".

[stgrhe]

 

4 - I also agree with most, that Thai electrical standards are either lax or not being enforced for new housing. But, I have seen good standards applied in new major construction at least in Bangkok.

What standards are you talking about? There are no existing electrical standards in Thailand, just practices, and that is something entirely different to legislated standards. A standard is by definition rules that have been legislated and therefore mandatory.

[CDNinKS]

OK - I'm not trying to step on anybody's toes or to raise emotions, but this "idiots reverse it at the meter" thing is NOT a problem and I really get annoyed when people cast off Thai's as idiots.

If you would have taken the time to read all the posts on this thread and others you will see that, as Crossy has tried to explain, this reversed L/N only affects MEN wired systems.

I agree that there are idiots all over the world and Thailand does not hold a monopoly on that, however lack of training/standards here allow unskilled people to mess around with things that they know nothing about.

[david96]

 

4 - I also agree with most, that Thai electrical standards are either lax or not being enforced for new housing. But, I have seen good standards applied in new major construction at least in Bangkok.

What standards are you talking about? There are no existing electrical standards in Thailand, just practices, and that is something entirely different to legislated standards. A standard is by definition rules that have been legislated and therefore mandatory.

Quite correct, there are no formal electrical standards that can be legally enforced in Thailand. Standards are for example IEC 60364 Low voltage Electrical Installations and AS/NZ3000/2007 Wiring Rules.

AS/NZ3000/2007 is mandatory and can be legally enforced in Australia and NZ.

[david96]

When the earthing system becomes energised due to a broken incoming neutral or the polarity has been reversed on an MEN system where the MEN bond is at the main neutral link and earth bar the touch voltage may exceed 50VAC. In some cases it will be over 90VAC.

This is potentially a hazardous situation and the problem must be rectified as soon as possible.

Disconection by automatic means is not available.

If the earth electrode connection is broken or has been disconnected that touch voltage may be full line voltage

and there will be no protection.

The effects of this touch voltage are minimised by earthing the structural metal and by equipotential bonding of incoming services, eg metal water pipes, reinforcing steel in concrete in wet areas.

With the TT earthing system is employed reversal of polarity will not cause a hazardous situation but all switches,and the protective devices will be switching the neutral conductor instead of the active conductor. In this case the earthing system will not become energised.

That main earth connection on a MEN ensures that the touch voltage does not reach full line voltage.

An MEN system has the neutral earthed at the point of supply,the transformer and at regular intervals on the distribution network and at each consumers main neutral.

This is not guaranteed in Thailand.

[elkangorito]

OK - I'm not trying to step on anybody's toes or to raise emotions, but this "idiots reverse it at the meter" thing is NOT a problem and I really get annoyed when people cast off Thai's as idiots.

If you would have taken the time to read all the posts on this thread and others you will see that, as Crossy has tried to explain, this reversed L/N only affects MEN wired systems.

I agree that there are idiots all over the world and Thailand does not hold a monopoly on that, however lack of training/standards here allow unskilled people to mess around with things that they know nothing about.

I have only seen three types of network distribution systems in Thailand, which in itself, is a worry. There should really only be one type for domestic installations.

Those types are as follows;

1] IT - neutral at transformer not earthed.

2] TT - neutral at transformer is earthed.

3] TN-(C-S) - neutral at transformer is earthed & neutrals are earthed at regular intervals along power poles.

As others have said (Crossy & David96), the reversal of L & N is only a problem with the TN-(C-S) network.

Due to the "Thainess" surrounding this situation, it is not important to use RCD's...IT IS CRITICAL & CRUCIAL!!! For your sake, make sure that RCD's are installed.

[david96]

I think you will find that there is no standard earthing system in Thailand and the IT system is widely used. This would explain the direct earthing system as implemented.

Probably Thai electrical engineering has been heavily influenced by Japan.

And it would explain why Thai engineers and electricians are vague concerning earthing.

Yet they understand earthing when it comes to lightning protection and earthing exposed metalwork on the HV/LV network.

Thailand and a lot of Asia is not as yet part of the IEC as far as standards go.

[dobadoy]

Are the meters now running backwards (wheel turning the opposite way?).

That's good news, buddy. Your electric bill is going DOWN with every watt you use!!