Ground or Neutral?

[Robin]

I am confused by the wiring I get from the PEA supply.   Looking at the poles in our village, it seems to be 3 wires, presumably the phases of a 3 phase supply, as each house a a supply wire to the meter coming from one of these wires.  Also on the poles is an uninsulated wire, from which the other supply wire to each house is taken.  A most poles, this wire is also run down the post to ground.  I had assumed that this wire was the neutral of the 3 phase supply and not an earth.

House wiring is one live wire, (1 phase from the supply) and the other wire which I thought should be the neutral(return) but is in fact a ground wire.

 

My first question:  is this true or m I not understanding what I see, and not understanding the "Thai Way" of electrics?

 

Secondly.  If there is no separate neutral return for he mains supply, can a RCD actually work?  

 

My experience of local village electricians is that they do not understand the difference between live and neutral supplies and see nothing wrong with putting a switch in the neutral supply to a light or appliance.  Nor do they appear to understand the purpose of a neon indicator screwdriver, though these are common in Thailand.  Since cable in Thailand can be either US or UK colour coded, local see not point in following any colour code convention

[Crossy]

Can you post a photo of the pole stuff please.

 

Thailand is mostly TNC-S with MEN, that means that the supply neutral is grounded regularly, every 3rd pole or so. It is also grounded in your distribution box by feeding the incoming neutral via the ground bar (older installations may not).

 

Some light reading here https://en.wikipedia.org/wiki/Earthing_system

 

The neutral and ground are actually the same thing (called the PEN - Protective Earth / Neutral), until they exit your incoming breaker at which point they are physically separate.

 

 

Much of the UK (and all of Oz) is wired like this, you just don't notice 'coz all the N-E linking goes on out of sight in the service head.

 

RCDs/RCBOs work just fine with this arrangement.

 

 

[Robin]

Crossy,  Thanks for the eplanation.  much as I have, except that in my home there has never been any connection between Earth and Neutral.  I note that, as you say, the supply neutral is grounded at every 3rd pole.

My electrician was not going to be bothered with a consumer unit, but incoming wires, 2x Al. cored cable, were brought to the house and then through a crude, 2 pole, knife type,  switch.  (Thai made, Chang brand,) and a RCB, to a plywood box containing a " birds nest" of wires and then to the rest of the house. No local connection between neutral and earth at my house.

House was built and wired when I was away, working, so no input from me.  All sockets were those horrible, Thai/Chinese, 2 pole things fro blade plugs, which he fitted to all appliances, presumably as they were the cheapest available.  Contact in each socket was intermittent and potentially death for compute/laptop switch mode psu.

With more time in Thailand, I have rewired most of the house, starting with a 6 way consumer until, purchased locally.  Wirng was repaced as I went along, uing some twin+earth bought from UK, and relacing sockets with either circular "European""  type sockets and compatible plugs on appliances, and later with the Thai 3pin sockets now readily available locally.

Because computer had mains input filter, I made a local earth so that I did no get a mild shock every time I touched the metal frame.  I followed conventional colour coding for wires, and made sure that the live supply was switched.

Local Thais considered that this was all nonsense and that I was a stupid Farang for not doing things the "Thai Way" 

I now consider that I have a house with fairly safe wiring, and no respect for any Thai electrician.

I have also found that it is impossible to get twin+earth cable in Thailand (Can somebody prove me wrong?)

I am not an electrician but a light current, electronics man, who has had to learn something about domestic wiring since I moved to Thailand.

[Crossy]

22 minutes ago, Robin said:

I have also found that it is impossible to get twin+earth cable in Thailand (Can somebody prove me wrong?)

 

It can still be difficult to get "out in the sticks", the big-box places tend to have it nowadays. The stuff you want is VAF-G 

https://www.bangkokcable.com/system/product/file_upload/210524_300!500V 70C VAF-G 2C_Rev04.PDF 

What's confusing is that is is still often labelled as "2 core".

 

Nobody will care but your UK T&E with a bare, reduced CSA, earth is actually illegal here.

[lopburi3]

As said three conductor wire has been available here for several decades and 3 pin outlets for all of the 50 years I have lived here - just not common (especially upcountry) as more expensive and few knew how to use (and actually the reason RCD has been made and is in common use here since the late 1970's - mine was made in 1978) - better to have ground/both but without ground the RCD has saved a lot of people.  

[topt]

7 hours ago, Crossy said:

 

It can still be difficult to get "out in the sticks", the big-box places tend to have it nowadays. The stuff you want is VAF-G 

https://www.bangkokcable.com/system/product/file_upload/210524_300!500V 70C VAF-G 2C_Rev04.PDF 

What's confusing is that is is still often labelled as "2 core".

 

Nobody will care but your UK T&E with a bare, reduced CSA, earth is actually illegal here.

Sorry Crossy but what is the reason in the link it says "Do not install in conduit"? (I note it says use for surface wiring and "installation in raceway"..........)

[Crossy]

5 minutes ago, topt said:

Sorry Crossy but what is the reason in the link it says "Do not install in conduit"? (I note it says use for surface wiring and "installation in raceway"..........)

 

Coz the Thai way is to use singles in conduit and use VAF for surface wiring. Just use it in conduit it will be fine, the larger sizes might be a bit of a wrestle to get in.

 

It's also OK to drape across your suspended ceiling unprotected.

 

[bankruatsteve]

It's usually cheaper to run singles through conduit and much easier to pull.  Just sayin.

[Led Lolly Yellow Lolly]

It's also easier to snag and damage the insulation, causing those impossible to trace RCD trips. I tend to deploy VAF in conduit, and ignore those that tell me it's against the law (it's not). I'll downrate the circuit where I do this.

 

 

On 6/20/2021 at 8:38 AM, Robin said:

 

I have also found that it is impossible to get twin+earth cable in Thailand (Can somebody prove me wrong?)

 

 

HomePro stock it but they're more expensive that your local supplier. I also get the "Thailaaaand no haab" line on a regular basis. Ignore that, BangkokCable and Thai Yazaki manufacture it. I have thousands of metres of it in my store room. When they tell you "Thailaaand no haab" what they're really saying is they can't be bothered to order it for you and they want you to buy what they have on their shelves instead.