Are there compulsory rules for grounding electrical devices?

[thomasteve]

Hi PeterAlex,

All your assumptions are correct, but as just about everyone has commented the standard wiring rules as we have come to learn in our own countries is not the case here, for example I am from Australia and in my past life I was an electrician, and International standards were met.. But Australia has what is called an MEN System which is Main Earth Neutral Bond, we take the earth wire from a stake (In Thailand this stake must be 1.8mtrs long), the Earth wire must be a minima of 4mm2, and connected to the earth bar in the Switchboard, but in Australia's case we than bond the earth bar to the Neutral bar with wire same size as the mains coming into the building, possibly 10mm2 or 16 mm2, and in my personal experience they use aluminium as the wiring for mains, This isn't a good practice as it adds to voltage drop, so whenever everyone of your neighbours turn on their lights and other appliances at night you will see your lights dim, .

Ok enough off the lessons- their was good advice given earlier - get a Safe- T -Cut Leakage breaker, even if their is no earth in the building the S-T-C will still operate as it looks for an imbalance between the Active (L) and Neutral (N) it does not reference Earth at all. But if current were to go to Earth hence an imbalance between L and N than the S-T-C will operate.

S-T-C's have some idiosyncrasies, the Refrigerator will be a problem, as we as appliances with a lot of water, such as Washing machines. It's a good idea to get the washing machine off the S-T-C obviously if you go away for the weekend you don't want your food gone bad as a result of a trip. But things like Washing Machines and dishwashers it is wise to keep them protected, as safety for the operator.

Ok enough of my ramblings.

Good luck.

There is no reason that a non faulty washing machine, dishwasher, or fridge is more likely to open an rcd

Nuisance tripping, as it's called, is more likely with appliances having heating elements where the insulation (white powder) contained within the metal element sheathing tends to absorb moisture and allow a small amount of current to 'leak'. Some installatons have electric cookers and water heaters that are not connected to an ELCB trip.

[Forkinhades]

All of these devices have a secondary rating known as the kA rating. This is the amount of current that the device can withstand before destroying itself and possibly anything nearby such as the power board or indeed starting a fire.

Very true, and indeed is another example of why it is important to measure the external earth with the right equipment. However unless you are right next to the transformer that is properly staked, I doubt if you will get anything low enough to cause this (0.04 ohms) for 6kA rated MCBs

[thomasteve]

The majority of shower heaters sold (reputable brands) now seem to have their own buit in earth leakage (similar to a saf-t-cut) protection device. Presumably these will still work correctly and provide adequate protection regardless of whether there is a correct earth wire connected to a ground rod or just a live and neutral supply connection ? The wire colours being mixed up will also be of no consequence if they are designed to operate by detection of a small imbalance (often 20mA) between the line and return (neutral) conductors ?

If you cannot get the house wiring correctly done,complete with an earthing rod, then at least install an ELCB (commonly sold as a saf-t-cut in Thailand) after the main on/off isolator switch before the rest of the circuits and associated mix-ups.

• Best not to have any presumptions with electricity
• With no earth the fault path will go through your body, do you really want that when having a shower?

Preventing it passing through the body is the purpose of the safety trip by acting quickly enough before a lethal current can flow to cause heart fibrillation.

The subject of earthing is quite complex and there are instances where having no earth connection at all can be safer than poor earthing connections or where proper earth bonding has not been done.

[Forkinhades]

The majority of shower heaters sold (reputable brands) now seem to have their own buit in earth leakage (similar to a saf-t-cut) protection device. Presumably these will still work correctly and provide adequate protection regardless of whether there is a correct earth wire connected to a ground rod or just a live and neutral supply connection ? The wire colours being mixed up will also be of no consequence if they are designed to operate by detection of a small imbalance (often 20mA) between the line and return (neutral) conductors ?

If you cannot get the house wiring correctly done,complete with an earthing rod, then at least install an ELCB (commonly sold as a saf-t-cut in Thailand) after the main on/off isolator switch before the rest of the circuits and associated mix-ups.

• Best not to have any presumptions with electricity
• With no earth the fault path will go through your body, do you really want that when having a shower?

Preventing it passing through the body is the purpose of the safety trip by acting quickly enough before a lethal current can flow to cause heart fibrillation.

The subject of earthing is quite complex and there are instances where having no earth connection at all can be safer than poor earthing connections or where proper earth bonding has not been done.

Can you be kind enough to give some examples please?

[Forkinhades]

Hi PeterAlex,

All your assumptions are correct, but as just about everyone has commented the standard wiring rules as we have come to learn in our own countries is not the case here, for example I am from Australia and in my past life I was an electrician, and International standards were met.. But Australia has what is called an MEN System which is Main Earth Neutral Bond, we take the earth wire from a stake (In Thailand this stake must be 1.8mtrs long), the Earth wire must be a minima of 4mm2, and connected to the earth bar in the Switchboard, but in Australia's case we than bond the earth bar to the Neutral bar with wire same size as the mains coming into the building, possibly 10mm2 or 16 mm2, and in my personal experience they use aluminium as the wiring for mains, This isn't a good practice as it adds to voltage drop, so whenever everyone of your neighbours turn on their lights and other appliances at night you will see your lights dim, .

Ok enough off the lessons- their was good advice given earlier - get a Safe- T -Cut Leakage breaker, even if their is no earth in the building the S-T-C will still operate as it looks for an imbalance between the Active (L) and Neutral (N) it does not reference Earth at all. But if current were to go to Earth hence an imbalance between L and N than the S-T-C will operate.

S-T-C's have some idiosyncrasies, the Refrigerator will be a problem, as we as appliances with a lot of water, such as Washing machines. It's a good idea to get the washing machine off the S-T-C obviously if you go away for the weekend you don't want your food gone bad as a result of a trip. But things like Washing Machines and dishwashers it is wise to keep them protected, as safety for the operator.

Ok enough of my ramblings.

Good luck.

There is no reason that a non faulty washing machine, dishwasher, or fridge is more likely to open an rcd

Nuisance tripping, as it's called, is more likely with appliances having heating elements where the insulation (white powder) contained within the metal element sheathing tends to absorb moisture and allow a small amount of current to 'leak'. Some installatons have electric cookers and water heaters that are not connected to an ELCB trip.

Are you suggesting that we should be testing our equipment with a high reading ohm meter (PAT Testing)?

[Crossy]

Preventing it passing through the body is the purpose of the safety trip by acting quickly enough before a lethal current can flow to cause heart fibrillation.

It's important to understand that the RCD does not limit the current, it simply detects it.

Touch a live wire and the current is limited only by your body resistance (say 1000 ohms) so a lethal 220mA will flow, the RCD sees this and opens, hopefully before you die (within 30ms).

The figure of 30mA as a trip current was chosen as it's big enough to limit nuisance tripping whilst being small enough to be non-lethal in the majority of fit adults. The elderly, infirm, sick, or young will succumb to much lower currents. That's why a half decent ground is still needed, in the event of a fault the current will flow through it and open the RCD rather than through you and open the RCD.

EDIT I've added some useful RCD information and links to the forum FAQ, here http://www.thaivisa.com/forum/topic/693823-faq-and-useful-documents/?p=7240255

[thomasteve]

Hi PeterAlex,

All your assumptions are correct, but as just about everyone has commented the standard wiring rules as we have come to learn in our own countries is not the case here, for example I am from Australia and in my past life I was an electrician, and International standards were met.. But Australia has what is called an MEN System which is Main Earth Neutral Bond, we take the earth wire from a stake (In Thailand this stake must be 1.8mtrs long), the Earth wire must be a minima of 4mm2, and connected to the earth bar in the Switchboard, but in Australia's case we than bond the earth bar to the Neutral bar with wire same size as the mains coming into the building, possibly 10mm2 or 16 mm2, and in my personal experience they use aluminium as the wiring for mains, This isn't a good practice as it adds to voltage drop, so whenever everyone of your neighbours turn on their lights and other appliances at night you will see your lights dim, .

Ok enough off the lessons- their was good advice given earlier - get a Safe- T -Cut Leakage breaker, even if their is no earth in the building the S-T-C will still operate as it looks for an imbalance between the Active (L) and Neutral (N) it does not reference Earth at all. But if current were to go to Earth hence an imbalance between L and N than the S-T-C will operate.

S-T-C's have some idiosyncrasies, the Refrigerator will be a problem, as we as appliances with a lot of water, such as Washing machines. It's a good idea to get the washing machine off the S-T-C obviously if you go away for the weekend you don't want your food gone bad as a result of a trip. But things like Washing Machines and dishwashers it is wise to keep them protected, as safety for the operator.

Ok enough of my ramblings.

Good luck.

There is no reason that a non faulty washing machine, dishwasher, or fridge is more likely to open an rcd

Nuisance tripping, as it's called, is more likely with appliances having heating elements where the insulation (white powder) contained within the metal element sheathing tends to absorb moisture and allow a small amount of current to 'leak'. Some installatons have electric cookers and water heaters that are not connected to an ELCB trip.

Are you suggesting that we should be testing our equipment with a high reading ohm meter (PAT Testing)?

No, are you ? I am just giving examples of home appliances that may cause nuisance tripping so were not connected to a RCD at the DB.

Cookers with their 4+ hotplates and elements for oven,grill etc could add up to enough current 'leaking' to cause unwanted tripping.

I have never experienced any problem with refrigerators,washing machines etc.

Portable small appliances, tools, garden equipment cause the majority of accidents but in recent years greater use of class 2 insulation has helped to reduce the number of fatalities from electrocution.

[thomasteve]

Preventing it passing through the body is the purpose of the safety trip by acting quickly enough before a lethal current can flow to cause heart fibrillation.

It's important to understand that the RCD does not limit the current, it simply detects it.

Touch a live wire and the current is limited only by your body resistance (say 1000 ohms) so a lethal 220mA will flow, the RCD sees this and opens, hopefully before you die (within 30ms).

The figure of 30mA as a trip current was chosen as it's big enough to limit nuisance tripping whilst being small enough to be non-lethal in the majority of fit adults. The elderly, infirm, sick, or young will succumb to much lower currents. That's why a half decent ground is still needed, in the event of a fault the current will flow through it and open the RCD rather than through you and open the RCD.

EDIT I've added some useful RCD information and links to the forum FAQ, here http://www.thaivisa.com/forum/topic/693823-faq-and-useful-documents/?p=7240255

Useful links. Do Saf-t-cut have a monopoly in Thailand ? If they were less expensive maybe more homes would have them fitted as standard .

[Crossy]

Useful links. Do Saf-t-cut have a monopoly in Thailand ? If they were less expensive maybe more homes would have them fitted as standard .

Only on the big, single box front-end units (I don't believe it's a true monopoly, they're just the only maker).

Nothing to stop you putting an ABB or Haco 2-pole RCD in one of those small DIN rail boxes and nailing it in front of your CU, obviously the RCD must be higher rated than the incoming MCB.

You'll need to do some juggling to get the MEN link in the right place mind, but if you're upgrading (rather than a new install that will be inspected) should be a piece of cake.

Probably about half the cost of a branded Safe-T-Cut.

[thomasteve]

Useful links. Do Saf-t-cut have a monopoly in Thailand ? If they were less expensive maybe more homes would have them fitted as standard .

Only on the big, single box front-end units (I don't believe it's a true monopoly, they're just the only maker).

Nothing to stop you putting an ABB or Haco 2-pole RCD in one of those small DIN rail boxes and nailing it in front of your CU, obviously the RCD must be higher rated than the incoming MCB.

You'll need to do some juggling to get the MEN link in the right place mind, but if you're upgrading (rather than a new install that will be inspected) should be a piece of cake.

Probably about half the cost of a branded Safe-T-Cut.

That's exactly what we did - using a Hager RCD in a separate box. (see photo)

As in Peter's situation the electrics are all mixed up, wrong colours and with the earth and neutral busbars both being used for neutral connections, probably as there is no external earth connection to an earthing rod fitted - earth wires just end at the CU. Many twisted and taped joins hidden above the ceilings.

[Piztolapete]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

[thomasteve]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

Be very careful when using those neon indicator test screwdrivers that you don't get a false indication for a live conductor.

They work by allowing a small current to pass through you (via a high resistor) to ground. So the neon will not glow brightly if you are insulated from the ground by wearing rubber soled footwear or standing on a wooden ladder or floor etc. which could mean you think a wire is not live when it is.

[bankruatsteve]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

Be very careful when using those neon indicator test screwdrivers that you don't get a false indication for a live conductor.

They work by allowing a small current to pass through you (via a high resistor) to ground. So the neon will not glow brightly if you are insulated from the ground by wearing rubber soled footwear or standing on a wooden ladder or floor etc. which could mean you think a wire is not live when it is.

I thought the neon screwdrivers worked from body (or other) capacitance. (?) Why would it need a ground?

[Crossy]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

Be very careful when using those neon indicator test screwdrivers that you don't get a false indication for a live conductor.

They work by allowing a small current to pass through you (via a high resistor) to ground. So the neon will not glow brightly if you are insulated from the ground by wearing rubber soled footwear or standing on a wooden ladder or floor etc. which could mean you think a wire is not live when it is.

I thought the neon screwdrivers worked from body (or other) capacitance. (?) Why would it need a ground?

Nope, definitely resistance to ground via you, if you're a particularly sensitive soul you can actually feel the current.

These beasts are frowned upon in the sparking community due to their (lack of) reliability.

NEVER use a neon to prove dead, if it lights it's live, if it doesn't light it's not live, or the neon is faulty, or your rubber shoes are stopping sufficient current flow.

And of course, there's always the story of the apprentice who dropped one in a bucket of water and then put it back in the toolbox...

That said, in the right hands and knowing the limitations they are a very useful tool.

[thomasteve]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

Be very careful when using those neon indicator test screwdrivers that you don't get a false indication for a live conductor.

They work by allowing a small current to pass through you (via a high resistor) to ground. So the neon will not glow brightly if you are insulated from the ground by wearing rubber soled footwear or standing on a wooden ladder or floor etc. which could mean you think a wire is not live when it is.

I thought the neon screwdrivers worked from body (or other) capacitance. (?) Why would it need a ground?

To allow a small amount of current to flow through your body to ground ,usually under 1mA, to light up the neon.

They are not 'fail-safe' and should not be used as a the only 'test' device although commonly used as such.

[bankruatsteve]

Hmm.

[thomasteve]

I thought the neon screwdrivers worked from body (or other) capacitance. (?) Why would it need a ground?

Nope, definitely resistance to ground via you, if you're a particularly sensitive soul you can actually feel the current.

These beasts are frowned upon in the sparking community due to their (lack of) reliability.

NEVER use a neon to prove dead, if it lights it's live, if it doesn't light it's not live, or the neon is faulty, or your rubber shoes are stopping sufficient current flow.

And of course, there's always the story of the apprentice who dropped one in a bucket of water and then put it back in the toolbox...

That said, in the right hands and knowing the limitations they are a very useful tool.

They are useful in identifying live from neutral and I usually use 2 of them to reduce the risk of relying on a faulty one as well as testing on a known live supply beforehand to make sure it's still working and I am making a good enough ground connection for the neon to light up.

Edited January 5, 2014 by thomasteve

[bankruatsteve]

I've never used one (prefer VOM) but if that's the way the neon thing works (I have been blasted for using VOM same, if that's the case) how can it have plastic casing and sparky on wooden ladder and the neon thing shows a live? Where is the earth connection?

'splain it to me Lucy.

[thomasteve]

I've never used one (prefer VOM) but if that's the way the neon thing works (I have been blasted for using VOM same, if that's the case) how can it have plastic casing and sparky on wooden ladder and the neon thing shows a live? Where is the earth connection?

'splain it to me Lucy.

Plastic casing yes, but you need to put your finger on the brass cap at the top which is connected through a high value resistor (to limit the current and prevent you getting a 'shock') to the neon bulb to the metal screwdriver shaft to the live wire.

From the metal cap whether it lights up or not depends on the remainder of the resistance path to ground and if it's sufficiently low to allow enough current, say 1mA, to flow.

Many factors can determine this, how long and wet or humid the wooden ladder is, whether he had his other hand or foot touching the wall, his skin dryness, type of shoes etc. So whether it lights up or not is a bit of a gamble.

[Crossy]

A non-contact tester is safer than a neon as there is no danger to the user if it fails, Voltstick are the classic manufacturer but there are many other brands http://www.voltstick.co.uk/product_voltstick_230Y.htm

Once again, do not use this to prove dead for the same reasons you shouldn't use a neon plus the Voltstick may have a flat battery.

[Forkinhades]

^ I totally concur with Crossy, and the test procedure should be.

Test on known voltage first to prove

Test cable you want to prove

Retest on known voltage to prove again

[Forkinhades]

This is the one I have from the local electrical wholesaler. It is both audible and visual, with a test button and led light at the front. Gives a good indication that there is enough power in the battery to prove.

Costs around 200 baht.

Something similar on RS Thailand costs 1500 baht

[Forkinhades]

Re : Post 35

Just to be clear and get complete transparency, I do actually agree that earthing needs to done properly, and if not can be more dangerous than if not installed at all. Was hoping you could have given an example.

with reference to the pinned thread 'How to make your thai electrics safe', what we are trying to do is educate people that here in Thailand it is more important to have your Safe-T-Cut installed, than to install earthing without a Safe-T-Cut. Which can become very dangerous indeed.

[Piztolapete]

You can buy a cheap tester for under 50 baht. Screwdriver with a light inside. Touch this to your conductors. The one that makes the light come on is your hot, the other your neutron conductor. I also just purchased an electric shower due to the cold weather. I installed it myself. Your most important connection is your ground. I do not have an impendence tester to test my ground system but I do have 2 meters of rods installed in very moist soil. A lot of appliances can be hooked up to with the wires reversed, however the shower can not be. I am currently enjoying my warm showers!!!!

Be very careful when using those neon indicator test screwdrivers that you don't get a false indication for a live conductor.

They work by allowing a small current to pass through you (via a high resistor) to ground. So the neon will not glow brightly if you are insulated from the ground by wearing rubber soled footwear or standing on a wooden ladder or floor etc. which could mean you think a wire is not live when it is.

Thank you for you concern. I have been an electrician for 21 years in Canada, doing electrical installs in houses, shopping malls, hospitals, factories, mines and oil refineries. My simple point is that you can be completely isolated from ground and likely should be while using this device. The screwdriver just uses the body capacitance for the potential. It is just a quick way to identify the N conductor. To ensure I had no Voltage I shut the main off and was shocked to find a gecko inside the switch with about forty hatched eggs. It was living under the cover that shields the metal strip fuses and must have made contact across as some point. Guess geckos are not good conductors. Unless your electric shower is designed to detect and auto switch like some appliances it must be hooked up correctly. My directions which came in the box and were also in English were quite specific.

[Piztolapete]

The majority of shower heaters sold (reputable brands) now seem to have their own buit in earth leakage (similar to a saf-t-cut) protection device. Presumably these will still work correctly and provide adequate protection regardless of whether there is a correct earth wire connected to a ground rod or just a live and neutral supply connection ? The wire colours being mixed up will also be of no consequence if they are designed to operate by detection of a small imbalance (often 20mA) between the line and return (neutral) conductors ?

If you cannot get the house wiring correctly done,complete with an earthing rod, then at least install an ELCB (commonly sold as a saf-t-cut in Thailand) after the main on/off isolator switch before the rest of the circuits and associated mix-ups.

I could not find one of the (reputable brands). So I got a Sharp WH-A55 3500 watt. The directions were very specific on the connection points. Connections must be made as to the manufacture's specs. Or a possible result of DEATH by electrocution could occur. If you could give me the models and manufacturers names I would look at that as possibility for future installs if I gift any of the extended family.

[Piztolapete]

20140106_072254-1.jpg

This is the one I have from the local electrical wholesaler. It is both audible and visual, with a test button and led light at the front. Gives a good indication that there is enough power in the battery to prove.

Costs around 200 baht.

Something similar on RS Thailand costs 1500 baht

Those are sometimes handy. However, they can give false indications on wires that have induced voltages. Though not likely here unless you have a bunch of cables in contact inducing the voltage from inductance.

[Forkinhades]

^ For me its a quick indication, and so much better than an neon. If it picks up induced voltages, then it's down to the individual to test further with the proper equipment right?

And of course the neon driver will pick up on induced voltages.

Sent from my GT-I9300 using Thaivisa Connect Thailand mobile app

[Crossy]

^ For me its a quick indication, and so much better than an neon. If it picks up induced voltages, then it's down to the individual to test further with the proper equipment right? Sent from my GT-I9300 using Thaivisa Connect Thailand mobile app

I'd rather a false positive (live) than a false negative (not live)

Induced 'phantom' voltages are a problem when using a DMM too, often an unconnected core will read about 1/2 supply due to capacitance.

This is one point where the really cheap analogue meters can score as they do actually slug the induced voltage.

[thomasteve]

The majority of shower heaters sold (reputable brands) now seem to have their own buit in earth leakage (similar to a saf-t-cut) protection device. Presumably these will still work correctly and provide adequate protection regardless of whether there is a correct earth wire connected to a ground rod or just a live and neutral supply connection ? The wire colours being mixed up will also be of no consequence if they are designed to operate by detection of a small imbalance (often 20mA) between the line and return (neutral) conductors ?

If you cannot get the house wiring correctly done,complete with an earthing rod, then at least install an ELCB (commonly sold as a saf-t-cut in Thailand) after the main on/off isolator switch before the rest of the circuits and associated mix-ups.

I could not find one of the (reputable brands). So I got a Sharp WH-A55 3500 watt. The directions were very specific on the connection points. Connections must be made as to the manufacture's specs. Or a possible result of DEATH by electrocution could occur. If you could give me the models and manufacturers names I would look at that as possibility for future installs if I gift any of the extended family.

By reputable brands I was thinking of Panasonic, Sharp, Stiebel Eltron etc. or others that have a built in ELCB which you can identify by seeing a 'test' button on the front panel. Some of the cheaper models don't have this protection but it's still advisable to have a Safe-t-cut or equivalent fitted rather than just rely on the internal one of the shower.

The shower instructions will emphasise the importance of earthing the unit but this is useless if you find that the earth wire just goes as far as the consumer unit as no earthing rod has been installed by cost cutting builders.

[thomasteve]

Re : Post 35

Just to be clear and get complete transparency, I do actually agree that earthing needs to done properly, and if not can be more dangerous than if not installed at all. Was hoping you could have given an example.

with reference to the pinned thread 'How to make your thai electrics safe', what we are trying to do is educate people that here in Thailand it is more important to have your Safe-T-Cut installed, than to install earthing without a Safe-T-Cut. Which can become very dangerous indeed.

Regarding the pinned thread it can be summarised as follows :

1. Install a Saf-t-cut or similar ELCB.

2. Ensure appliances and socket outlets are correctly earthed and an earthing rod is installed.

3. Never add a Neutral to Earth MEN link unless you are 100% sure it is required by your supplier.

As for an example of a scenario where earthing can present a danger :

House has no Saf-t-cut or ELCB but has correctly earthed fixed large appliances and socket outlets.

User purchases a metal cased small appliance (rice-cooker, toaster, iron etc.) fitted with a 2 pin plug or Schuko type European plug that does not provide correct earth connection.

This small appliance becomes faulty and the metal casing live but user remains unaware as he is insulated from ground (rubber soled sandals, wooden floor etc.) but then touches another correctly earthed appliance (cooker,fridge) with other hand and will receive severe shock. If there had been no earthing then there would be no potential difference to allow current to pass through user and cause a shock.

I am not advising against earthing but it needs to be done properly and in conjunction with an ELCB.

Edited January 6, 2014 by thomasteve