Grounding Electrical Outlets ?

[rexall]

Sun 9 Nov 08, 9:00 am

Hi all,

I am pretty clueless about this stuff, so please be nice.

I rent a house, and long-overdue, finally decided to get a few of the outlets, especially to my computer equipment, grounded. The problem is, while I understand the principle, I have no idea how it should be done properly. However, we managed to find a crew who had just completed some grounding work nearby, so I assumed they knew what they were doing.

Adding a piece of equipment (I forget what it is called), and then grounding everything through the main fuse box seems ideal, obvoiusly--but as this isn't my house, I don want to do anything that heroic, my thought was just to ground a few individual outlets. I assumed that they would change the two-pin outlets for three-pin, and then run the grounding wire from the outlets. They "almost" did that. But they did NOT replace my outlets however. I have a bunch of power-strips/surge protectors everywhere, and they have run the ground wire from each of those. Also, downstairs they ran the ground from the UBC box, rather than changing the outlet, which would seem to protect the cable box but not the teevee or DVD player. As UBC has already replaced three cable boxes FREE due to lightning, that seems to miss the point a little.

Anyway, as I said, I really don't have a good basis for knowing whether what these guys did was incompetent, lazy, misguidedly economical . . . or if it was OK . . . or what.

Anyway, I would appreciate any counsel as the boys are returning tomorrow to finish up a few bits and bob, and and I will have them do the job properly so long as I have enough info to make an intelligent decision and tell them what to do.

Thanks, lah!

Aloha,

Rex

Edited November 9, 2008 by rexall

[djc45]

I have asked the way the wiring works in Thailand and have it explained by highly educated electrical technician working in the uk the following

In Thailand its is not the same as the uk it would appear from the information I gave him about the electrical supply to my house in Issarn.

From the supply substation they only send a live feed and the second feed that you see over head is NOT a neutral supply feed but an earth a neutral is not needed to power up anything,

You can test this in the uk by wiring a light bulb up with the live wire to a live in a 3 pin plug and the neutral to the earth terminal in the plug and the bulb will light

The way it has been explained to me is that in the uk you would get a live feed and a neutral feed from the substation and the earth would be taken from a local source such as an incoming lead pipe or copper pipe or earth spike

Here in Thailand it would seem that the (neutral) is in fact a cable that just goes into the earth this is connected to the neutral terminal giving you the false idea that you have a neutral feed

If you then try to introduce an earth feed by way of a earth spike you could in fact cause more problems as any short to earth through the earth feed could return via the neutral wire

Most electric showers if not all that are sold in Thailand have a built in ELB with an earth wire connected to an earth spike un like the electric showers you see in the uk this is so that the power is switched of at the shower and the live cannot continue to the earth spike and back to the false neutral feed

If you look close at your incoming over head wires that supplies the incoming electricity you can see that the neutral wire when traced back to the joint has an UN insinuated wire running down the concrete pole into a conduit that goes into the earth

I hope this will shed some light on the subject

Edited November 9, 2008 by djc45

[Lite Beer]

Info. here Rex.

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

Rex I see from your other life that you have already looked at the above.

I am by no means expert in electrics.

We had our house grounded and the electrician changed the wall sockets to 3 pin.

There are some real experts here and hopefully they will not be too long with some advise.

[PoorSucker]

I had this explained to me many years ago.

"In Thailand we not need ground"

[dotcom]

Incorrect.

[elkangorito]

I have asked the way the wiring works in Thailand and have it explained by highly educated electrical technician working in the uk the following

In Thailand its is not the same as the uk it would appear from the information I gave him about the electrical supply to my house in Issarn.

It appears that the electrical supply to your house is by SWER, one of many types of power distribution systems.

Thailand does not predominantly use this system to supply residences in urban areas.

The SWER system is primarily used to supply power to remote locations that have few consumers.

[Crossy]

To continue from Elkangoritos comments, take a look at the attached document that describes some of the systems used.

Thailand uses TT and a variant of TN-C-S known as MEN or PME where the neutral is grounded at multiple points not just at the transformer. The neutral aerial is often un-insulated to reduce costs, it poses no hazard as it is near ground potential.

Untitled_Extract_Pages_3.pdf

You'll have to rotate the pages, for some reason the software I used to extract from the original document turned everything through 90 degrees

Elk. I thought that SWER was used only for the 11kV local feed, LV domestic being copper/aluminium both ways? Interesting info here http://www.ruralpower.org/index.php?option...=2&Itemid=3

DJC45 If your poles have two wires the you definately do NOT have SWER and the bare wire is neutral, if it is grounded perodically then you have MEN

Edited November 9, 2008 by Crossy

[Wandering]

My experience.

I was getting shocked by my computer and other appliances (fridge, washer, etc..)

The only thing in my home that the electrician had grounded was the hot water heater. It was a green wire from the back that wrapped around the iron window bar (not very safe)

Note: A lot of what look like 3 prong surge bars here are in fact only 2 prong extension cords.

What I did.

I installed 3prong outlets all over my home (near any expensive appliances) then strung a 3rd green wire along the other wire but then (instead of going to the main fuse box) had the wires meet and go out the window and into the ground.

I inserted a 1 foot long copper rod (better than aluminum or tin) into the ground. I attached the green wire to the top of that. The ground needs to stay moist yearlong so I put it near the aircon drip.

This may not be a perfect solution, but I don't get shocked anymore.

[elkangorito]

To continue from Elkangoritos comments, take a look at the attached document that describes some of the systems used.

Thailand uses TT and a variant of TN-C-S known as MEN or PME where the neutral is grounded at multiple points not just at the transformer. The neutral aerial is often un-insulated to reduce costs, it poses no hazard as it is near ground potential.

Untitled_Extract_Pages_3.pdf

You'll have to rotate the pages, for some reason the software I used to extract from the original document turned everything through 90 degrees

Elk. I thought that SWER was used only for the 11kV local feed, LV domestic being copper/aluminium both ways? Interesting info here http://www.ruralpower.org/index.php?option...=2&Itemid=3

DJC45 If your poles have two wires the you definately do NOT have SWER and the bare wire is neutral, if it is grounded perodically then you have MEN

Hi Crossy.

Australia uses both 22kV & 33kV (phase-to-phase) feeds for SWER. An earth cable may run above the HT SWER feed in lightning prone areas.

[elkangorito]

To continue from Elkangoritos comments, take a look at the attached document that describes some of the systems used.

Thailand uses TT and a variant of TN-C-S known as MEN or PME where the neutral is grounded at multiple points not just at the transformer. The neutral aerial is often un-insulated to reduce costs, it poses no hazard as it is near ground potential.

Untitled_Extract_Pages_3.pdf

You'll have to rotate the pages, for some reason the software I used to extract from the original document turned everything through 90 degrees

Elk. I thought that SWER was used only for the 11kV local feed, LV domestic being copper/aluminium both ways? Interesting info here http://www.ruralpower.org/index.php?option...=2&Itemid=3

DJC45 If your poles have two wires the you definately do NOT have SWER and the bare wire is neutral, if it is grounded perodically then you have MEN

Hi Crossy.

Australia uses both 22kV & 33kV (phase-to-phase) feeds for SWER. An earth cable may run above the HT SWER feed in lightning prone areas.

Just checked a Soi near my place...2 phase HT supply (22kV) & an earth cable running above.

[jojothai]

I have asked the way the wiring works in Thailand and have it explained by highly educated electrical technician working in the uk the following

In Thailand its is not the same as the uk it would appear from the information I gave him about the electrical supply to my house in Issarn.

From the supply substation they only send a live feed and the second feed that you see over head is NOT a neutral supply feed but an earth a neutral is not needed to power up anything,

You can test this in the uk by wiring a light bulb up with the live wire to a live in a 3 pin plug and the neutral to the earth terminal in the plug and the bulb will light

The way it has been explained to me is that in the uk you would get a live feed and a neutral feed from the substation and the earth would be taken from a local source such as an incoming lead pipe or copper pipe or earth spike

Here in Thailand it would seem that the (neutral) is in fact a cable that just goes into the earth this is connected to the neutral terminal giving you the false idea that you have a neutral feed

If you then try to introduce an earth feed by way of a earth spike you could in fact cause more problems as any short to earth through the earth feed could return via the neutral wire

...

Hi djc45 and others

This has got me somewhat confused and I think we should try to clarify the above.

From what I read elsewhere, and as stated above it is dangerous to have two earth connections.

From what djc45 says if the neutral is in fact an earth in Thailand then we surely should never put an additional earth spike unless we are sure it will be safe!!

Why are spikes readuily on sale at all retailers and from what I see they are being bought to install?

Also, if the neutral is an earth, why do we have the third wire for earth at all?

I must be misunderstanding something.

I am about to put in the earth spike and wire to the CU and have a few questions:

1. Should I put in an earth spike? Do I need to get any special check done on the incoming neutral to ensure it is an earth or not and will be safe?

2. If the neutral is an earth and I should not connect an earth spike then what do we do with the earth wiring? Do we connect it all to the MEN link (connecting to the neutral) to treat it as an earth. And as above - If so, what is the point of the third wire if the neutral is already the earth?

3. If I put an earth spike and run wire to the consumer unit, I note on crossy's wiring site a recommendation for 10mmsq.

I have some 1.5mm sq and 2.5 mm sq earth wire leftover from circuit installation and could make this into say 3 or 4x1.5 and 2x2.5 to combine for the equivalent of 9.5 / 11 mmsq (All wires made in a single run).

Is this possible or should I make it a single 10mmsq cable.

I would be grateful if Crossy could confirm if the multiple wire idea is considered acceptable?

regards

jojo

[jojothai]

Going back to my last post.

I have read the articles again and guess I need to figure out whether I should put TT (NO MEN) or the TN-C-S with MEN.

How can I establish which will be safe?

I guess I have to know if the existing line neutral is earth and if so, is it is far enough away for us to safely put our own grounding pin.

Pictures may help to show the situation regarding the electrical lines, see below.

The existing branch line runs from the "connection post" at the main line at the road to an "intermediate post" and then to an "existing post near the new house". The branch line has 2 wires. PEA say they are aluminium.

My location is over 100m from the main electricity line and there is a very large canal (several meters wide) between the intermediate post and the new house.

In the photos I have tried to show each post and then the clearest pictures I have of the typical wire layout on the main road line.

On the picture of the "connection post" at the main road it does look like there may be a wire going to the ground. I will have to look at it when I get back to the province tomorrow.

Being over 100m away from the main line could this be far enough not to worry and just put our own earth pin together with the MEN.

regards

jojo

[Crossy]

^^^

It is always safe to assume TT and not install a MEN link. The neutral is always grounded at the transformer no matter which system is in use and a few extra ground points only improve the grounding. As I've said before only install a MEN link if you KNOW it is implemented.

The issue with multiple ground points (which incidentally are NOT prohibited by UK regs) is the possibility of circulating ground currents causing significant ground potentials which could (and have) injure animals by having a voltage between front and back legs, typically a problem associated with SWER systems.

There is NO problem with having your own ground spike even if you are on a TN-C-S, you are simply adding yet another ground to the already multiply-grounded neutral.

Not wishing to flame other members, but I think djc45 has mis-interpreted what he was told, or his 'highly educated' tech is not so knowledgable as first thought

Edited November 12, 2008 by Crossy

[elkangorito]

Comments in blue.

^^^

It is always safe to assume TT and not install a MEN link. The neutral is always grounded at the transformer no matter which system is in use and a few extra ground points only improve the grounding. As I've said before only install a MEN link if you KNOW it is implemented.

It has become apparent to me that this is not always the case in Thailand.

The issue with multiple ground points (which incidentally are NOT prohibited by UK regs) is the possibility of circulating ground currents causing significant ground potentials which could (and have) injure animals by having a voltage between front and back legs, typically a problem associated with SWER systems.

Multiple earth electrodes are not prohibited but are not suggested unless the tested Earth Fault Loop Impedance is less than required. Multiple earth electrodes must be installed in accordance with the regulations.

There is NO problem with having your own ground spike even if you are on a TN-C-S, you are simply adding yet another ground to the already multiply-grounded neutral.

Not wishing to flame other members, but I think djc45 has mis-interpreted what he was told, or his 'highly educated' tech is not so knowledgable with the electrical distribution system in Thailand as first thought

[jojothai]

Comments in blue.

^^^

It is always safe to assume TT and not install a MEN link. The neutral is always grounded at the transformer no matter which system is in use and a few extra ground points only improve the grounding. As I've said before only install a MEN link if you KNOW it is implemented.

It has become apparent to me that this is not always the case in Thailand.

The issue with multiple ground points (which incidentally are NOT prohibited by UK regs) is the possibility of circulating ground currents causing significant ground potentials which could (and have) injure animals by having a voltage between front and back legs, typically a problem associated with SWER systems.

Multiple earth electrodes are not prohibited but are not suggested unless the tested Earth Fault Loop Impedance is less than required. Multiple earth electrodes must be installed in accordance with the regulations.

There is NO problem with having your own ground spike even if you are on a TN-C-S, you are simply adding yet another ground to the already multiply-grounded neutral.

Not wishing to flame other members, but I think djc45 has mis-interpreted what he was told, or his 'highly educated' tech is not so knowledgable with the electrical distribution system in Thailand as first thought

Thanks Elkangorito and Crossy

Therefore doesnot appear to be a risk if I connect the earth spike with the MEN. That was my main worry.

I had one further question concerning the earthing wire to the spike.

For the wire from the earth spike to the consumer unit, I note on crossy's wiring site a recommendation for 10mmsq.

I have some 1.5mm sq and 2.5 mm sq earth wire leftover from circuit installation and could make this into say 3 or 4x1.5 and 2x2.5 to combine for the equivalent of 9.5 / 11 mmsq (All wires made in a single run).

Is this idea acceptable or should I make it a single 10mmsq cable.

regards

jojo

[dotcom]

I inserted a 1 foot long copper rod (better than aluminum or tin) into the ground. I attached the green wire to the top of that. This may not be a perfect solution, but I don't get shocked anymore.

You are almost there.

Go to an electrical supply store or Home Pro & buy a proper ground rod. They are normally copper & about 10 feet/3 m long. Be sure to buy the clamp they sell just for this job. I believe Crossy says these should not be exposed, rather buried or sheathed in concrete.

[dotcom]

I guess I have to know if the existing line neutral is earth and if so, is it is far enough away for us to safely put our own grounding pin.

There is a simple way to find out, assuming you have run your third (ground) wire.

Get a multi-meter. Being very careful set it to the lowest AC volt setting (greatest sensitivity). Measure between earth & neutral. At my house at least I do read voltage across this curcuit.

My experience is that neutral here is not zero potential but very close to it.

Most of us have run our own ground systems - now it is the code here (don't laugh). We ran them for a very good reason. Neutral is not Ground.

P.S. A wire run to a window frame is NOT a ground. It is someones idea of a joke.

[Wandering]

P.S. A wire run to a window frame is NOT a ground. It is someones idea of a joke.

Sadly it was not done as a joke. It was ignorantly done as a solution. Aaarrrrrggghhhh

[chrisyork]

Have to say I am very nervous about earthing an electrical installation at least in rural Thailand. Reasonably close observation suggests that almost everything is TT and my impression is there are quite a few faults around on adjacent parts of the system. If you install an earth on your property there is some risk of trying to pull down all the faults from miles around!! Personally I think the better solution is an ELCB on the mains incomer and RCD's on any socket outlets!

Chris

[dingdongrb]

Going back to my last post.

I have read the articles again and guess I need to figure out whether I should put TT (NO MEN) or the TN-C-S with MEN.

How can I establish which will be safe?

I guess I have to know if the existing line neutral is earth and if so, is it is far enough away for us to safely put our own grounding pin.

Pictures may help to show the situation regarding the electrical lines, see below.

The existing branch line runs from the "connection post" at the main line at the road to an "intermediate post" and then to an "existing post near the new house". The branch line has 2 wires. PEA say they are aluminium.

My location is over 100m from the main electricity line and there is a very large canal (several meters wide) between the intermediate post and the new house.

In the photos I have tried to show each post and then the clearest pictures I have of the typical wire layout on the main road line.

On the picture of the "connection post" at the main road it does look like there may be a wire going to the ground. I will have to look at it when I get back to the province tomorrow.

Being over 100m away from the main line could this be far enough not to worry and just put our own earth pin together with the MEN.

regards

jojo

As if wiring schemes in LOS tell you amything.....

Edited November 16, 2008 by dingdongrb

[jojothai]

Have to say I am very nervous about earthing an electrical installation at least in rural Thailand. Reasonably close observation suggests that almost everything is TT and my impression is there are quite a few faults around on adjacent parts of the system. If you install an earth on your property there is some risk of trying to pull down all the faults from miles around!! Personally I think the better solution is an ELCB on the mains incomer and RCD's on any socket outlets!

Chris

hi chris

I get a feeling I need to be careful.

I thought TT was just your own earth. No MEN.

what dotcom says I should check the reading.

as you say about elcb, I am putting in sense consumer units with elcb and surge suppression.

a little extra cost but the units do give a better control on where I want elcb and I think I will then be able to easily correct any problem tripping.

regards

jojo

[jojothai]

Have to say I am very nervous about earthing an electrical installation at least in rural Thailand. Reasonably close observation suggests that almost everything is TT and my impression is there are quite a few faults around on adjacent parts of the system. If you install an earth on your property there is some risk of trying to pull down all the faults from miles around!! Personally I think the better solution is an ELCB on the mains incomer and RCD's on any socket outlets!

Chris

hi chris

I get a feeling I need to be careful.

I thought TT was just your own earth. No MEN.

what dotcom says I should check the reading.

as you say about elcb, I am putting in sense consumer units with elcb and surge suppression.

a little extra cost but the units do give a better control on where I want elcb and I think I will then be able to easily correct any problem tripping.

regards

jojo

[Crossy]

Have to say I am very nervous about earthing an electrical installation at least in rural Thailand. Reasonably close observation suggests that almost everything is TT and my impression is there are quite a few faults around on adjacent parts of the system. If you install an earth on your property there is some risk of trying to pull down all the faults from miles around!! Personally I think the better solution is an ELCB on the mains incomer and RCD's on any socket outlets!

There is no problem installing an earth to a TT system, the issue is whether to provide a local ground of the neutral (by installing a MEN / PME link). As you rightly say you could end up pulling all sorts of interesting ground currents.

As I've said repeatedly, don't install a MEN link unless you KNOW it has been implemented in your area. A regular ground stake backed up by an ELCB will provide more than enough protection.

[jojothai]

There is no problem installing an earth to a TT system, the issue is whether to provide a local ground of the neutral (by installing a MEN / PME link). As you rightly say you could end up pulling all sorts of interesting ground currents.

As I've said repeatedly, don't install a MEN link unless you KNOW it has been implemented in your area. A regular ground stake backed up by an ELCB will provide more than enough protection.

hi Crossy

thanks for clarifying.

on the other subject of earth spike wiring.

is it ok to run multiple wires to get 10 sqmm or should it be just one wire 10sqmm.

I have spare 2.5sqmm earth wire single run I can combine to give the 10 if it is ok.

regards

jojo

[Crossy]

on the other subject of earth spike wiring.

is it ok to run multiple wires to get 10 sqmm or should it be just one wire 10sqmm.

I have spare 2.5sqmm earth wire single run I can combine to give the 10 if it is ok.

Sorry Mate, I'm obviously suffering brain-fade in my rapidly advancing years, thought I'd already answered that

Yup, should be no problem using multiple 2.5s so long as they all run between the same two points (no zipping off to the other side of the house). Take care that they all make good contact via the stake clamp, twist the cores together before applying the clamp and don't forget to apply acrylic paint to the connection to protect it.

Edited November 18, 2008 by Crossy

[jojothai]

on the other subject of earth spike wiring.

is it ok to run multiple wires to get 10 sqmm or should it be just one wire 10sqmm.

I have spare 2.5sqmm earth wire single run I can combine to give the 10 if it is ok.

Sorry Mate, I'm obviously suffering brain-fade in my rapidly advancing years, thought I'd already answered that

Yup, should be no problem using multiple 2.5s so long as they all run between the same two points (no zipping off to the other side of the house). Take care that they all make good contact via the stake clamp, twist the cores together before applying the clamp and don't forget to apply acrylic paint to the connection to protect it.

thanks crossy.

understood.

regards

jojo