The earthing of refrigerators

[Crossy]

3 minutes ago, JohanB said:

I still very much oppose this half hearted and absolute dangerous MEN connection in Thailand.

This type of connection is wrong to use, as there is no reliable ground wire comming in to the house!

 

Australia, the UK, the US and much of the 220V 3-phase, 4-wire world would disagree.

 

Of course Thailand (unlike Australia) does allow TT connections so it's entirely up to you.

 

Please explain under what circumstances properly implemented TNC-S with MEN (PME in the UK) is hazardous?

 

 

[JohanB]

36 minutes ago, Crossy said:

 

Australia, the UK, the US and much of the 220V 3-phase, 4-wire world would disagree.

 

Of course Thailand (unlike Australia) does allow TT connections so it's entirely up to you.

 

Please explain under what circumstances properly implemented TNC-S with MEN (PME in the UK) is hazardous?

 

 

I already explained in my post what a broken neutral coul do.

 

Here is more from Wiki if you dont belive me!

...................

• ”In single-ended single-phase systems where the Earth and neutral are combined (TN-C, and the part of TN-C-S systems which uses a combined neutral and earth core), if there is a contact problem in the PEN conductor, then all parts of the earthing system beyond the break will rise to the potential of the L conductor. In an unbalanced multi-phase system, the potential of the earthing system will move towards that of the most loaded line conductor. Such a rise in the potential of the neutral beyond the break is known as a neutral inversion.^[9] Therefore, TN-C connections must not go across plug/socket connections or flexible cables, where there is a higher probability of contact problems than with fixed wiring. There is also a risk if a cable is damaged, which can be mitigated by the use of concentric cable construction and multiple earth electrodes. Due to the (small) risks of the lost neutral raising 'earthed' metal work to a dangerous potential, coupled with the increased shock risk from proximity to good contact with true earth, the use of TN-C-S supplies is banned in the UK for caravan sites and shore supply to boats, and strongly discouraged for use on farms and outdoor building sites, and in such cases it is recommended to make all outdoor wiring TT with RCD and a separate earth electrode.”

 

https://en.m.wikipedia.org/wiki/Earthing_system

 

As most houses in thailand have over head 2 separate wires (not coaxial!) single phase elecric coming in to the fuse box, the neutral wire is very vurnable and exposed to be cut by accident.

 

Also what I experianced in my country hut some years ago, was after a tree blown down, a faulty repair made where the live and neutral wires were shifted when spliced.

[Trollmann]

43 minutes ago, Crossy said:

 

Except that the hole in the plug and the outlet do not align properly. Damage to the outlet will ensue.

 

DO NOT DO THIS!!

 

i do this and there is absolutely no problem doing this. I dont have to force the plug into position and the device is grounded properly. There is absolutely no damage to the outlet and i inserted and pulled the plug houndreds of times already. The earth pin in the plug is not tightened and because it is smaller in diameter it fits pretty well into the outlet. The diameter on my earth pin is about 2 mm smaller than the true thai plug earth pin diameter

[sometimewoodworker]

1 hour ago, JohanB said:

I still very much oppose this half hearted and absolute dangerous MEN connection in Thailand.

This type of connection is wrong to use, as there is no reliable ground wire comming in to the house!

The ground rod is normally just inserted in the soil (if you’re lucky) and is not able to carry the current to blow a fuse.

You are demonstrating a rather concerning lack of electrical knowledge, considering the dangers you are promoting. The TNC-S with MEN system does not require on earth supplied by the PEA/MEA the neutral is earthed at roughly every 3rd pole. The requirement is for a whole house RCD (other letters exist) so the earth rod is not required to carry the current to trip the RCD.

 

Virtually the entire UK wiring system uses the same (different acronym) system.

 

Using Wikipedia as a primary reference just reinforces the problem. Wikipedia may point you in the direction of documents to look up, but as anyone can post anything it is a terrible reference.

[JohanB]

4 hours ago, sometimewoodworker said:

You are demonstrating a rather concerning lack of electrical knowledge, considering the dangers you are promoting. The TNC-S with MEN system does not require on earth supplied by the PEA/MEA the neutral is earthed at roughly every 3rd pole. The requirement is for a whole house RCD (other letters exist) so the earth rod is not required to carry the current to trip the RCD.

 

Virtually the entire UK wiring system uses the same (different acronym) system.

 

Using Wikipedia as a primary reference just reinforces the problem. Wikipedia may point you in the direction of documents to look up, but as anyone can post anything it is a terrible reference.

 You’re absolutely wrong and I probably know electric more than most people here.

 

I warned about what an open neutral will do in a single phase TN-C-S MEN system.

A RCD/RCBO will NOT trip and save you if you get a leathal chock from a live carrying shower tap/hose!

The voltage and deadly current will pass the heaters coil through and back in the RCD core in the right order not to trip it, then into the ground wire and to the waterheater ground and hose!

The eventual house ground-rod can not carry that current!

Only a real low impedance ground (wich you don’t have) can lead away that current and save you.

 

If you have low knowledge of electric and dont understand how this can be possible, an UK man has made an explanation of that:

 

 

 

[Crossy]

@JohanB we all understand the risks associated with an open PEN conductor in a TNC-S system, of that there is no doubt.

 

The key is the addition of "MEN" or "PME". By earthing the neutral at regular intervals along the line (every 3rd pole) and by having a local rod at each installation there should be a sufficiently low return resistance to keep a disconnected neutral (and connected earth) within reasonable voltage levels.

 

Also, on an aerial supply system the neutral is the top wire of the four, so any vehicle taking out the neutral will also take out the phases.

 

IMHO and that of many (supposedly) more expert than any of us, the advantage of having a solid metallic earth connection back to the star point far outweighs the slight risk from a broken neutral.

 

As I noted earlier, here you have the choice to go TT, many places (Aus/NZ) you don't get a choice and in the UK you likely don't know if your supply is TNC-S or TNS anyway as the N-E connection is sealed in the service head.

 

Also (and this is important) I never would suggest adding a MEN link to an existing TT installation unless one is certain that the necessary grounding points on the neutral have been installed. Luckily this is easily verified by observation whilst walking the dog.

 

EDIT It's also worth considering the following.

Let's assume you have a TT system with a rod resistance of, say, 20 ohms (that's a pretty good rod), you also have an RCBO.

 

You get L-E fault in your shower, about 11A strarts to flow to earth (limited by the rod resistance) and the "earthed" metalwork approaches 220V. Unfortunately your RCBO earth detection has gone faulty, 11A isn't going to trouble the 30A MCB, you die!

 

In the past 20 odd years I have read of far more failed RCBOs than I have open neutrals.

 

 

[sometimewoodworker]

6 hours ago, JohanB said:

 You’re absolutely wrong and I probably know electric more than most people here.

 

You have managed to carefully conceal that knowledge by your choice of Wikipedia as supposed definitive refferance, as the many errors in it mean that it can never be a trusted source.

 

John Ward  certainly knows his subject.

[Crossy]

OK Gentlemen. We have no way of validating anyone's qualifications or experience (or lack of same) so let's not start down the "my dad is bigger than your dad" route.

 

Both TT and TNC-S  supplies have their place and there isn't really a one size fits all solution (add IT into the mix for more fun).

 

The fact is that Thailand's supply authorities (MEA and PEA) require the provision of the MEN connection, a 2.4 metre local ground rod and front end RCBO in order to pass the inspection for a permanent supply. What you do once you've passed the inspection is entirely up to you.

 

I will continue recommending sticking to the local regulations "รหัสมาตรฐาน EE 2001-56  มาตรฐานการติดตั้งทางไฟฟ้าสำหรับประเทศไทย พ.ศ. 2556" (Standard EE 2001-56 Electrical Installation Standard for Thailand, 2013). Sadly not available in English. Buy it here https://eitstandard.com/product/10201-57/ or your local bookstore 225 Baht - it seems you can download it too. 

 

Unfortunately there's not a Thai equivalent of BS7671 or AS3000 which would make life easy. The best we can do is the information published by PEA which is linked in one of the pinned threads.

 

[bankruatsteve]

No matter what one's qualifications, relying on hyperbole to make a point puts me off for sure.

[Crossy]

If you are still paranoid (we all are when it comes to getting zapped) you could make an open-neutral detector using a plain old RCD (it should be a 100mA unit to avoid nuisance tripping). This thread from 2011 popped up in a google search, I don't even remember writing it.

 

https://forum.thaivisa.com/topic/457002-the-hazard-of-an-open-circuit-neutral/

 

[antoniuni]

Crossy: 

 

"a 2.4 metre local ground rod and front end RCBO in order to pass the inspection for a permanent supply." ??????????

[Crossy]

6 minutes ago, antoniuni said:

"a 2.4 metre local ground rod and front end RCBO in order to pass the inspection for a permanent supply." ??????????

 

When you build your home you get a temporary "construction supply", anything goes on your side of the meter but power is billed at 8 Baht per unit.

 

In order to get a "permanent" meter and be billed at a nicer 4 Baht per unit you must pass an inspection. It's pretty rudimentary with no actual testing going on, our inspector spent 5 minutes looking in the board and at the top of the rod and 30 minutes gassing to the Missus and drinking our imported Italian coffee.

 

From an earlier post (extract from PEA brochure), my translations.

 

[antoniuni]

Thanks for your answer Crossy! But this "inspection" is 100% useless! I was living in several houses and even one house had an earth connection from the contacts but............no earth cable to outside! And when you see my photo about the manufactured earthed power plug with two cables: disgusting! 

[Crossy]

18 minutes ago, antoniuni said:

Thanks for your answer Crossy! But this "inspection" is 100% useless! I was living in several houses and even one house had an earth connection from the contacts but............no earth cable to outside! And when you see my photo about the manufactured earthed power plug with two cables: disgusting! 

 

It depends upon when the supply was connected, inspections have only been required relatively recently and of course inspectors are susceptible to "lubrication". Indeed I have seen brand new homes with no RCBO and only 2-pin outlets ????

 

But of course, we are not in the market for bypassing safety regulations.

[bankruatsteve]

Just an anecdote to illustrate how up-country mentality can be swayed...

 

Not too many years ago, almost all the houses in this area were (still are) constructed of wood and raised on tree trunk supports.  These structures are effectively insulated from "ground".  Adding ground would be superfluous and has convinced some folk to believe "ground" is a Western issue.

[rwill]

Some of the plugs don't have an earth pin on them but a metal strip running down the side.  Like the plug shown earlier in this thread.  You can buy an adapter which slides over the plug to provide the earth pin.  

[Fruit Trader]

16 hours ago, JohanB said:

I still very much oppose this half hearted and absolute dangerous MEN connection in Thailand.

This type of connection is wrong to use, as there is no reliable ground wire comming in to the house!

The ground rod is normally just inserted in the soil (if you’re lucky) and is not able to carry the current to blow a fuse.

 

In the scenario that the incoming neutral wire is cut somewhere, all what you belive ”grounded” appliances will carry live 220V on their cabinets, if the ground rod current don’t blow a fuse

 Even the water heater ground in your bathroom will be live.

 

(Also the neutral and ground is interchanged on the outlet in the drawing)

By ground coming into the house I am sure you mean the poor standard of ground provided by local rods.

 

Considering Thailand's poor standards coupled with the fact that implementation of TNC-S requires good standards, I can fully understand your concerns. Don't bother yourself with the knowledge bullying, your good intentions are appreciated by some.

 

As a knowledgeable person you do have the advantage of being able to alter your supply arrangement if not happy with the supply network outside of your property.

[johng]

On 6/6/2019 at 5:05 AM, Crossy said:

Also, on an aerial supply system the neutral is the top wire of the four, so any vehicle taking out the neutral will also take out the phases.

Is the neutral the top wire in this photo ?  seems a bit thin.

 

 

[bankruatsteve]

20 minutes ago, johng said:

Is the neutral the top wire in this photo ?  seems a bit thin.

That's for the line walkers.

[Crossy]

46 minutes ago, johng said:

Is the neutral the top wire in this photo ?  seems a bit thin.

 

No those are the 25kV incoming, the thinwire at the top is lightning protection.

It's the 4 small insulators lower down the pole which are the 220V.

 

EDIT I just took this of our pole.

 

Starting at the top:-

 

• The very thin wire is the lightning protection, it's supposed to dump the flashy-bangy stuff before it gets to the next level.
• The 3 wires on big insulators are the 25kV supply which goes to the transformer.
• Next down on the smaller insulators we have the 220V, top (bare) is neutral, then the three phases.
• The lonely insulator is the control for the street lighting.
• Then the tangle of phone and fibre.

 

 

 

 

[johng]

16 minutes ago, Crossy said:

thinwire at the top is lightning protection. 

Ahh ok

 

17 minutes ago, Crossy said:

It's the 4 small insulators

These then ?

 

 

[Crossy]

1 minute ago, johng said:

These then ?

 

Yup ????

 

[johng]

27 minutes ago, Crossy said:

Then the tangle of phone and fibre.

[samtam]

I bought a Samsung fridge and today they came to install it. 

 

The plug was a two-prong and they were going to attach the earth wire by tapes to the cable and then insert the earth wires into the third (earth) point of the wall socket.

 

 

 

I said "no". So they have taken the fridge away, and I've cancelled the order.

 

I find it strange that this method is up to code.

 

Having read the previous posts on here, it seems they could have cut the sealed two prong plug, and inserted all three wires into a three point plug, but it would still leave the green and yellow earth wire attached by electrical tape to the outside of the main electric cable.

 

Would that still be safe? The fridge has plumbed-in water for ice making and chilling water, and although the water hose feed is below the electrical socket, I was feeling very uneasy about the naked wires.

 

The present LG fridge I have has a properly earthed plug, but Samsung have said all their fridges in Thailand are installed the way I have described.

[Crossy]

It would be perfectly safe to remove the 2 pin plug and replace with a 3-pin with the earth wire connected, taping the earth to the flex isn't neat but it's not hazardous. Our freezer is installed like this. 

 

Or you could run a pigtail from the earth inside the outlet and connect to the earth from the fridge. Not recommended but would avoid warranty issues from removing the moulded plug.

 

Is the Schuko plug in your last photo what's fitted to your LG fridge? I hope you have used the correct adaptor to plug into your outlet (or you have a Schuko outlet). Otherwise your fridge isn't earthed.

 

 

[samtam]

Thanks for your reply.

I understand the plug change, and I think the pigtail method was being suggested by them...the earth wire through the socket, which would making unplugging difficult.

 

The LG Schuko plug does not have an adaptor or a Schuko outlet. At no stage has anyone suggested this was not earthed, (including the installers yesterday)!

 

I have a box of adapters including these two, but I'm not clear whether a Schuko adapter should have 3 prongs?

 

Furthermore, as it's a new product, and it is not manufactured with an earthed plug, is earthing necessary? (I can't understand why it would be manufactured without earthing.)

 

Sorry for the ignorance. I should have had our condo technician up whilst the aborted installation was going on, as he's a wizard.

[sometimewoodworker]

18 minutes ago, samtam said:

The LG Schuko plug does not have an adaptor or a Schuko outlet. At no stage has anyone suggested this was not earthed, (including the installers yesterday)!

 

do you really expect installers to say anything!

 

the plug is earthed therefore the appliance is earthed, that you don’t have the correct socket is hardly their problem. 5555555
 

If you have plugged your earthed schuko plug into almost any but a schuko socket without an adapter your appliance is not earthed 

 

schuko plug and socket

 

adapter

[bankruatsteve]

Lazada has this one:

https://www.lazada.co.th/-i261440047-s402335233.html?urlFlag=true&mp=1

[Metropolitian]

1 hour ago, samtam said:

Thanks for your reply.

I understand the plug change, and I think the pigtail method was being suggested by them...the earth wire through the socket, which would making unplugging difficult.

For the pigtail method and 'unplugging-problem'. Three solutions.  Solution two is the safest.

 

1. This solution uses two sockets and doesn't need destroying the original 2 prongs plug:

Connect the green/yellow wire to the earth terminal of a new 3 prong plug.

 

2. This solution is not suitable when the socket is in reach of children and un-technically persons.:

An aprx. 15 cm pigtail wire from the earth inside the socket and twist it with the green/yellow wire from the fridge. Tape finish. Unplugging cost a few seconds extra.

 

3. This solution is sturdy but don't make a mistake by plugging in the wrong hole:

Get a banana plug, fix the wire to the plug and plug the plug in the earthplug hole after you plug the two prongs in the socket.

 

 

1 hour ago, samtam said:

The LG Schuko plug does not have an adaptor or a Schuko outlet. At no stage has anyone suggested this was not earthed, (including the installers yesterday)!

 

I have a box of adapters including these two, but I'm not clear whether a Schuko adapter should have 3 prongs?

Tuck this useless adapter far away in a drawer as you will probably never need it.

It is good for in USA or Japan, give it to someone who lives there.

Too few places here that still have the need for a euro to usa adapter, many sockets here do accept the euro plugs.

Only a few old extension cords and some 1:1 transformers then you will need this, but general use nope ????

 

 

1 hour ago, samtam said:

Bin..unless you have wall sockets (Japan/USA style) without earth hole or are working with electronics that has a 3 prongs plug but not wanting the earth connected.  (For example when technicians want measure the mains with their oscilloscope, earth need to be disconnected.)

 

Or tuck it away in the above drawer together with the other adapter ????

 

 

If you had this kind of plug the other way then it would be kind of useful someday. Like this one..

I still have it in the farrest corner of the least used drawer here.

Used it a few times with a extension cord which has 3 hole sockets but the earth hole inside wasn't connected at all. (the cord was 2 core)

It is originally for wall sockets with only 2 prongs and pigtail connection (Japan).

 

[samtam]

Thanks, Metropolitan. 

Is earthing necessary?

I've obviously been running my old fridge for 15 years without it being earthed.

I have the Shucko on all my kitchen appliances, but without adapters, and not in Shucko sockets, and I have never had any electrical faults/shocks.