Electrician

llso · February 11, 2007

Hi Guys,

Looking for a competent Thai Electrician, Know they exist. In the Lower BR area near Prakhon Chai. Already have the electric in the house 15A service . Need to hook up a commercial grade water heater , left over bits from my factory.

Thanks in advance,

LL

Thaddeus · February 12, 2007

Hi Guys,

Looking for a competent Thai Electrician, Know they exist. In the Lower BR area near Prakhon Chai. Already have the electric in the house 15A service . Need to hook up a commercial grade water heater , left over bits from my factory.

Thanks in advance,

LL

Go to the very large hardware store on the road from Prakhon Chai to Surin (practically opposite the Driving Centre) and ask the boss lady in there who she would recommend.

3NI9MA · February 12, 2007

LL

You say a commercial grade water heater, and a 15A service - do you mean this as, an available MCB or fuseway on the electric board OR the incoming electrical supply to your house?

What is the stated Wattage on the heating element?

If you, divide the Wattage (3000) by voltage (220) this will give you the current required.

So your heater cannot really be larger than 3KW for that supply.

The cable required would need to be 2.5mm 3core (Live Neutral + Earth) and make sure the earthing is connected at both ends!

You should also have a decent double pole switch to isolate - I have seen lots of inadequate (cheaply produced) electrical fittings, for sale in Thailand, better quality in Home-pro.

I wouild also have an RCD fitted to further protect against electrical shocks, as you have added a electrical potential to the water outlets - even though the waterpipes are plastic.

You should also check the (wattage/amp) rating of the external electrical meter - to see if this is capable.

Lastly, make sure all connections are fully tightened to prevent arcing across contacts.

llso · February 12, 2007

LL
You say a commercial grade water heater, and a 15A service - do you mean this as, an available MCB or fuseway on the electric board OR the incoming electrical supply to your house?

What is the stated Wattage on the heating element?

If you, divide the Wattage (3000) by voltage (220) this will give you the current required.

So your heater cannot really be larger than 3KW for that supply.

The cable required would need to be 2.5mm 3core (Live Neutral + Earth) and make sure the earthing is connected at both ends!

You should also have a decent double pole switch to isolate - I have seen lots of inadequate (cheaply produced) electrical fittings, for sale in Thailand, better quality in Home-pro.

I wouild also have an RCD fitted to further protect against electrical shocks, as you have added a electrical potential to the water outlets - even though the waterpipes are plastic.

You should also check the (wattage/amp) rating of the external electrical meter - to see if this is capable.

Lastly, make sure all connections are fully tightened to prevent arcing across contacts.

Thanks,

That is some good information. The meter is 15A I was told to make sure to get the 15A meter because we also have 2 small air conditioners I will be hooking up later.

Got the electric done in the house about a year and a half ago by one of the locals who was a very good electrician. He even grounded (Earthed) the sytem which you know is a rarity here. The ground rod was a little short not the usual 8' one I am used to in the US. The guy that originally did the work actually works in BKK but happened to be in the village at the time we were doing the work. Even the man from the PEA was impressed by the quality of his work.

The main box is a 100A Square D breaker box from Home Pro in BKK. I haven't checked the wattage on the heater as it is still buried with all of the other stuff in the warehouse we built a while back. It is not too large about the size of a small microwave and mounts on the wall. The only thing though is at our factory thr hot water line which was to the sink to clean our utensils (seafood processing ) was done in copper pipe. I'm not sure if they have the CPVC pipe here that can be used for hot water.

I am also going to get one of those Safe T cut ground fault systems too. Thanks again . I am not living there at the house except visiting a few times a year. I should be back sometime in March and that is when I am planning to do this work.

LL

3NI9MA · February 13, 2007

LL

I am from the UK and the electrical regulations there are stringent.

All copper pipework needs to be earthed, if hot and cold run together they need to be cross-bonded with a earth wire. etc.

More recently, plumbers are using CPVC (on a coil) with push fit adaptors for C/H systems! Then earthing clamps should be fitted to the radiators etc, to protect against shocks from electricity conducted by the water.

The length of the earth rod, is not always the case, it's the conductivity of the ground it is staked into.

Earthing rods are used in conjuction with RCDs, and are normaly associated with overhead power supplies (most UK households are "underground" and have different requirements).

On the Supply being connected, tests are performed to make sure RCDs operate in the prescribed time.

I would suggest that you have recieved some incorrect information, with the meter size, somewhere.

Normally, a meter rated at 15amp would be OK for a Thai country house - Take into account what would get plugged into a normal supply, such as...

Fridge, TV, Fan /s. Err. what else? Oh, and a strip light. have I miissed anything, yeah, a VCD Player for karaOK.

You need to calculate the potential of your electrical appliances (if all turned on at once), then you use this to calculate the required size (amparage) of the Meter.

I do not know what sizes are available. The house I live in has a 40A meter - I doubt if I shall ever exceed this. I think, an 15a meter must be the smallest size produced, therefore is liable to burning out.

A example, though this is NOT the meter I discribe, simular princibles will occur.

I was plagued with problems when I tried to boil a kettle with something else on!

I discovered there was only a 15a in-coming fuse that kept blowing (burning out). I temporary solved this by uprating a 20A d/p switch/breaker, then I rewired using a MCB board from the UK.

If you should have any other questions feel free to ask.

Pink Mist · February 13, 2007

LL
I am from the UK and the electrical regulations there are stringent.

All copper pipework needs to be earthed, if hot and cold run together they need to be cross-bonded with a earth wire. etc.

More recently, plumbers are using CPVC (on a coil) with push fit adaptors for C/H systems! Then earthing clamps should be fitted to the radiators etc, to protect against shocks from electricity conducted by the water.

The length of the earth rod, is not always the case, it's the conductivity of the ground it is staked into.

Earthing rods are used in conjuction with RCDs, and are normaly associated with overhead power supplies (most UK households are "underground" and have different requirements).

On the Supply being connected, tests are performed to make sure RCDs operate in the prescribed time.

I would suggest that you have recieved some incorrect information, with the meter size, somewhere.

Normally, a meter rated at 15amp would be OK for a Thai country house - Take into account what would get plugged into a normal supply, such as...

Fridge, TV, Fan /s. Err. what else? Oh, and a strip light. have I miissed anything, yeah, a VCD Player for karaOK.

You need to calculate the potential of your electrical appliances (if all turned on at once), then you use this to calculate the required size (amparage) of the Meter.

I do not know what sizes are available. The house I live in has a 40A meter - I doubt if I shall ever exceed this. I think, an 15a meter must be the smallest size produced, therefore is liable to burning out.

A example, though this is NOT the meter I discribe, simular princibles will occur.

I was plagued with problems when I tried to boil a kettle with something else on!

I discovered there was only a 15a in-coming fuse that kept blowing (burning out). I temporary solved this by uprating a 20A d/p switch/breaker, then I rewired using a MCB board from the UK.

If you should have any other questions feel free to ask.

I very rarely give electrical advice, for reasons that crossy and a few others appreciate.

I do get annoyed when handy men give advice and I am convinced you are one.

You are trying to be helpfull but this is one area best left to the professionals and I am one.

elkangorito · February 13, 2007

If you should have any other questions feel free to ask.
I very rarely give electrical advice, for reasons that crossy and a few others appreciate.

I do get annoyed when handy men give advice and I am convinced you are one.

You are trying to be helpfull but this is one area best left to the professionals and I am one.

I second the above motion.

3NI9MA · February 14, 2007

OK, bronco and elkangorito.

I take your point, about giving advice - I know I am leaving myself open.

If you are English bronco, you will know what I mean with C&G, IEEE Approved 16th edition. So do you want my JIB card No now???? or references...

I mainly worked on large Industrial or Commerecial projects, NOT Household / house bashing or re-wires, as these WERE NOT my idea of fun.

When I sold up to in 2002 to live here I obviously gave up electrical work.

I responded to LL as I have seen the standard of the work here in Thailand. The only thing good is the neatness of the clipping of the cables!

Pink Mist · February 14, 2007

OK, bronco and elkangorito.
I take your point, about giving advice - I know I am leaving myself open.

If you are English bronco, you will know what I mean with C&G, IEEE Approved 16th edition. So do you want my JIB card No now???? or references...

I mainly worked on large Industrial or Commerecial projects, NOT Household / house bashing or re-wires, as these WERE NOT my idea of fun.

When I sold up to in 2002 to live here I obviously gave up electrical work.

I responded to LL as I have seen the standard of the work here in Thailand. The only thing good is the neatness of the clipping of the cables!

I am an Aussie and work in Power Generation at the moment, have allways worked in specialist areas, lifts, mining etc and have really not spent a great deal of time wire jerking.

Having said that I have kept pace with the requirements of domestic installations and testing and last year did a nationally recognised course on installation testing (paid for by western mining coorporation 55555).

As I said I dont like giving advice onhow to do stuff, it's just not that simple, most electricians do a 4 or 5 year apprentiship to qualify them, sorry if I came down a bit hard but thats life I guess.

citizen33 · February 14, 2007

OK, bronco and elkangorito.
I take your point, about giving advice - I know I am leaving myself open.

If you are English bronco, you will know what I mean with C&G, IEEE Approved 16th edition. So do you want my JIB card No now???? or references...

I mainly worked on large Industrial or Commerecial projects, NOT Household / house bashing or re-wires, as these WERE NOT my idea of fun.

When I sold up to in 2002 to live here I obviously gave up electrical work.

I responded to LL as I have seen the standard of the work here in Thailand. The only thing good is the neatness of the clipping of the cables!

I am an Aussie and work in Power Generation at the moment, have allways worked in specialist areas, lifts, mining etc and have really not spent a great deal of time wire jerking.

Having said that I have kept pace with the requirements of domestic installations and testing and last year did a nationally recognised course on installation testing (paid for by western mining coorporation 55555).

As I said I dont like giving advice onhow to do stuff, it's just not that simple, most electricians do a 4 or 5 year apprentiship to qualify them, sorry if I came down a bit hard but thats life I guess.

citizen33 · February 14, 2007

I have to say that I am a little bemused by the put downs aimed at 3N19MA. Although his language was a bit obscure and there might have been some oddities in terminology and things that didn't really apply to Thailand, I thought that the 3 main points he raised made sense. 1. The 15A supply (the second level you can opt for in a domestic supply in the NE) is rather marginal for a system with aircon and a larger water heater. 2. It is a good idea to earth your system. 3.An RCCB isn't a bad investment. If there is one thing that I find more tiresome than an amateur offering advice on a web board, it is a 'expert' suggesting that a post contains errors without giving the correct answers. That has all the hallmarks of protecting the trade, but is a dangerous game in Isaan where the 'chang fi-fa' may be far below the standard of the western electrician. Having seen a 'professional' happily snip out an earth cable provided for an air con installation, I don't think it is a bad idea if the punters try to get some basic information. As to Bronco, well an expert on NE nightlife who thinks the Lighthouse Bar is the centre of the universe has a credibility problem.

3NI9MA · February 16, 2007

My previous posts there was terminology for the layman – this is what obviously set off bronco, I found his reaction strange as a moderator – he should have asked or deleted the post.

But as a mod he can be elitist with himself, and make himself look good.

one area best left to the professionals and I am one

…sorry if I came down a bit hard but thats life I guess. - Nah, Life is what you make it !

bronco states he attended a course on installation testing. I would have given him more kudos for this if he had paid himself – like I used to, to keep my JIB rating.

As I stated, I had no experience of plastic piping, so I did get that slightly wrong, erring on the side of safety. http://www.iee.org/Publish/WireRegs/EarthingPlasticPipes.pdf

I managed to correctly identify;

The minimum size of cable.

The KWH meter had short-comings, for the anticipated load.

And the earth rod requirements.

This is what LL needed to know in his quest for a Thai electrician. That was all that mattered, case closed…

Thai, Aus/NZ and the UK are 3 separate regions, with different standards or are they?

The UK is a founder member along with the US, of The International Electrotechnical Commission (IEC) which now includes many European countries, as well as Australia as members – so the IEC standards should be one.

BTW. Thailand is not a member!

The IEC is an international standards organization dealing with electrical, electronic and related technologies. Some of its standards are developed jointly with ISO. Standards

The UK does not have many overhead systems – I had always lived in Essex / East London and I cannot think of ONE. I learnt this in my appreticeship or updates, I cannot remember which.

I pm’d Elkangorito as I found his documents interesting and said I would refer others there, he had at least made a contribution to the forum – Kudos for this, so others could follow his lead.

He then mailed me back, to say he thought Thailand’s electrical distribution and climate was more akin to Australia’s – I believe in this he meant TN C S (MEN).

After re-reading Residential wiring.doc and digesting it fully. I will now make the following comments.

International standard IEC 60364 distinguishes three families of earthing arrangements using the two-letter codes TN, TT, and IT.

TN C S: Part of the system uses a combined PEN conductor, which is at some point split up into separate PE and N lines. The combined PEN conductor typically occurs between the substation and the entry point into the building, whereas within the building separate PE and N conductors are used. In the UK, this system is known as Protective Multiple Earthing (PME), because of the practice of connecting the combined neutral and earth to real earth at many locations (the incomer) to reduce the risk of broken neutrals.

Australia has designated a similar system known as Multiple Earthed Neutral (MEN).

In the wiring diagram, the Neutral does not looked switched. A UK PME system has double pole (L&N) switching, to totally isolate the instalation.

Sorry Elkangorito Thailand’s system, fits the description of a IEC – “TT standard” java script:add_smilie("","smid_4")

ohmy.gif

“This arrangement covers installations not provided with an earth terminal by the Electricity Supply Company. Thus (TT) it is the method employed by most installations fed by an overhead supply”.

(That adequately describes EVERY supply I have seen in Thailand)

The Neutral and earth conductors must be kept quite separate throughout the installation, with the final earth terminal connected to an earth electrode by means of an earthing conductor.

Effective earth connection is sometimes difficult.

(So what did I say about the length of earthing stakes and ground resistance? This is what BS 7430 : 1998 ‘Code of Practice for Earthing’ has to say)

The soil resistivity of the ground is probably the single most important factor in the determination of the type of earth electrode. Rods can only be as effective as the contact they make with the surrounding material. Thus, they should be driven into virgin ground, not disturbed (backfilled) ground.

Many new Thai houses have raised land or sit on disturbed ground.

Where it is necessary to drive two or more rods and connect them together to achieve a satisfactory result, the separation between rods should be at least equal to their combined driven depth to obtain maximum advantage from each rod. In some locations low soil resistivity is found to be concentrated in the topsoil layer, beneath which there may be rock or other impervious strata which prevents the deep driving of rods, or a deep layer of high resistivity. Only a test or known information about the ground can reveal this kind of information. In such circumstances, the installation of copper earth tapes, or pipes or plates, would be most likely to provide a satisfactory earth electrode resistance value.

I learnt that many years ago, when I was installing “clean earths” and filtered supplies. As opposed to “dirty” supplies that would have wreck havoc on the computers rooms / mainframes that I was working on.

Back to the TT description

Because of this, socket outlet circuits must be protected by a residual current device (RCD) with an operating current of 30 mA

There is a difference between ELCB’s and RCDs / RCBO’s

An Earth Leakage Circuit Breaker is a device with two earth terminals used to directly detect currents leaking to earth from an installation and cut the power. They were mainly used on TT earthing systems before RCDs became common. They have been almost totally replaced by RCDs due to a number of problems.

They do not allow a system to be easily split into multiple sections with independent fault protection, due to the fact that earthing systems are usually bonded to things like pipework.

They may be tripped by external voltages on something connected to the earthing system such as metal pipes, a TN-S earth or a TN-C-S combined neutral and earth.

They introduce additional resistance and an additional point of failure into the earthing system.

Regulation 5.9.4 - Fault voltage operated circuit breakers

These circuit breakers, commonly known in the trade as 'voltage ELCBs', were deleted from the 15th Edition of the Wiring Regulations in 1985, and should not be installed. It is advisable that installations where they are still in use should be carefully tested prior to a change to residual current device protection.

- This is what I believe SafeTcuts are, and Elkangorito makes several references to ELCB’s.in other notes 3/

These were made obsolete in the UK 22years ago

A Residual Current Device is an electrical wiring accessory that disconnects a circuit whenever it detects that the flow of current that is not balanced between the phase (live) conductor and the neutral conductor. The presumption is that such an imbalance may represent current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A shock, possibly lethal, is likely to result from these conditions; RCDs are designed to disconnect quickly enough to prevent such shocks.

The choice of the most suitable RCD for a particular application should take into account Sensitivity:

10mA RCDs offer a high degree of protection against electrocution in an accidental shock hazard situation. They are of particular value in a high risk area where resistances external to the body are likely to restrict the earth fault current flowing through the body to less than 30mA and where 110V supply is being used.

30mA RCDs offer a high degree of protection in an accidental shock hazard situation and are by far the most popular sensitivity used in the United Kingdom.

In a shock situation, the current flowing through the human body at 240V 50Hz could be between 80 and 240mA, depending on the resistance of the body in question. To ensure that there are no harmful physiological effects in such a situation, it is necessary for the RCD to operate within 300mS at 30mA and 40mS at 150mA. As the RCD typically operates well below these times, it clearly more than satisfies this requirement.

100mA and 300mA RCDs are also available, but would not be sensitive enough.

Regulation 5.9.3 - Regulations for residual current devices (RCDs and RCBO’s)

The primary purpose of the residual current device is to limit the severity of shock due to indirect contact. In other words, it will detect and clear earth faults which otherwise would could lead to dangerous potential differences between pieces of metalwork which are open to touch. If the sensitivity of the device (its operating residual current) is low enough, it may also be used to limit the shock received from direct contact in the case of the failure of other measures.

In some cases RCD are designed so that their operating parameters, such as the rated residual current or the time delay, can be adjusted. If such an RCD can be operated by an ordinary person (rather than by a skilled or instructed person then such adjustments must only be possible by a deliberate act using a key or a tool which results in a visible indication of the setting. it appears that Australian Standards fit almost perfectly where other standards may cause problems.

RCDs must never be used as the sole method of direct contact protection (Earthjng), but are invaluable in providing supplementary protection in high risk environments.

A Residual Current Breaker with Overload is a combination of an RCD and a miniature circuit breaker (MCB).

Both RCD’s and RCBO’s will operate in a -25 to 40C temperature zone.

Elkangorito's Other notes taken from his “residential wiring doc”

1/

An individual Earth Leakage protection device (ELCB or RCD) should not protect the entire residential electrical installation. Individual Earth Leakage protection devices are recommended for each Power Circuit/Lighting Circuit. This is because that some appliances like old refrigerators/air conditioners have a high residual earth leakage & can therefore cause nuisance tripping. As appliances become older, residual earth leakage becomes more apparent. Would you want your whole electrical supply to trip because of one appliance? In such situations, people who have their whole house supply protected by one (1) earth leakage device, tend to increase the trip current to overcome this nuisance tripping. This ultimately defeats the purpose of Earth Leakage protection. It usually ends up being turned off or removed.

The usage of RCBOs seems to be alluded to, but not named – I am not aware of their availability in Thailand.

2/.

Only half of the lighting circuits shall be protected by earth leakage devices. In the event of a fire or a similar emergency, it is not recommended that all of the lighting circuits be disabled. How can you find your way out if all the lights trip on earth leakage?

Agree

3/.

Earth Leakage Protection Devices are electronic & hence, are not reliable. They can fail without notice. Also, these devices will not detect a fault if you become connected between ‘active’ & ‘neutral’. It will not trip under such circumstances & you will be electrocuted (although you may not die). Also, many Earth Leakage Protection Devices do not detect ‘half wave’ faults. An example of such a fault is where a hair dryer is used in a bathroom. The hair dryer is being used on a reduced ‘heat’ setting & both the user & the hair dryer come into contact with water. In this situation, some types of Earth Leakage Protection Devices will not detect the fault & therefore will not trip. Ensure that your Earth Leakage Protection Device will protect against ‘half wave’ faults.

A sticker is on the C/Unit warns that RCDs / RCBOs should be monthly tested by pressing the “Test” button (which will simulate a ground fault by bypassing some current) and see if the RCD reacts correctly opening the circuit. If it does not trip, the RCD should be replaced

Also the complete installation should be professionally checked every 10yrs.

I do not know of any cases where someone has been electrocuted and survived… electrocution is fatal. Until fatality happens, it is classed as a severe electric shock!

A RCD/RCBO would detect the hairdryer fault using PME

4/.

An MEN link is crucial for your safety. Also, ensure that your appliances are correctly earthed. DO NOT rely upon Earth Leakage Protection Devices to save your life. They are Secondary to an MEN Link & a correct earthing system.

Provided it has been correctly installed and not been tampered with.

As the saying goes - Do not monkey around with electricity _ or this happens.

http://www.thaivisa.com/forum/style_images...e_types/gif.gif

taken Ko Lanta

This is more like it - Meter Thai style, from the vilage I live in. http://www.thaivisa.com/forum/style_images...e_types/gif.gif

http://www.thaivisa.com/forum/style_images...e_types/gif.gif

So how many potential faults... ????

elkangorito · February 17, 2007

My comments in purple.

My previous posts there was terminology for the layman – this is what obviously set off bronco, I found his reaction strange as a moderator – he should have asked or deleted the post.
But as a mod he can be elitist with himself, and make himself look good.

one area best left to the professionals and I am one

…sorry if I came down a bit hard but thats life I guess. - Nah, Life is what you make it !

bronco states he attended a course on installation testing. I would have given him more kudos for this if he had paid himself – like I used to, to keep my JIB rating.

As I stated, I had no experience of plastic piping, so I did get that slightly wrong, erring on the side of safety. http://www.iee.org/Publish/WireRegs/EarthingPlasticPipes.pdf

I managed to correctly identify;

The minimum size of cable.

The KWH meter had short-comings, for the anticipated load.

And the earth rod requirements.

This is what LL needed to know in his quest for a Thai electrician. That was all that mattered, case closed…

Thai, Aus/NZ and the UK are 3 separate regions, with different standards or are they? Aus & NZ share the same standards, the only differences being air & soil ambient temperatures.

The UK is a founder member along with the US, of The International Electrotechnical Commission (IEC) which now includes many European countries, as well as Australia as members – so the IEC standards should be one.

BTW. Thailand is not a member! Australian Standards are largely adopted from the IEC/ISO standards & have been modified for Australian environmental conditions. Please note - Thailand & Australia share very similar ambient are & soil temperatures (climate), voltage, frequency & distribution network (TT). If the direct application of IEC/ISO standards are used for Thailand without being normalised to the Thai climate & electrical characteristics etc, serious error may occur.

The IEC is an international standards organization dealing with electrical, electronic and related technologies. Some of its standards are developed jointly with ISO. Standards

The UK does not have many overhead systems – I had always lived in Essex / East London and I cannot think of ONE. I learnt this in my appreticeship or updates, I cannot remember which.

I pm’d Elkangorito as I found his documents interesting and said I would refer others there, he had at least made a contribution to the forum – Kudos for this, so others could follow his lead.

He then mailed me back, to say he thought Thailand’s electrical distribution and climate was more akin to Australia’s – I believe in this he meant TN C S (MEN).

After re-reading Residential wiring.doc and digesting it fully. I will now make the following comments. Australia uses the TT network & has been for the last 35 years as far as I know.

International standard IEC 60364 distinguishes three families of earthing arrangements using the two-letter codes TN, TT, and IT.

TN C S: Part of the system uses a combined PEN conductor, which is at some point split up into separate PE and N lines. The combined PEN conductor typically occurs between the substation and the entry point into the building, whereas within the building separate PE and N conductors are used. In the UK, this system is known as Protective Multiple Earthing (PME), because of the practice of connecting the combined neutral and earth to real earth at many locations (the incomer) to reduce the risk of broken neutrals.

Australia has designated a similar system known as Multiple Earthed Neutral (MEN).

In the wiring diagram, the Neutral does not looked switched. A UK PME system has double pole (L&N) switching, to totally isolate the instalation.

Sorry Elkangorito Thailand’s system, fits the description of a IEC – “TT standard” java script:add_smilie("","smid_4")

ohmy.gif

“This arrangement covers installations not provided with an earth terminal by the Electricity Supply Company. Thus (TT) it is the method employed by most installations fed by an overhead supply”.

(That adequately describes EVERY supply I have seen in Thailand)

The Neutral and earth conductors must be kept quite separate throughout the installation, with the final earth terminal connected to an earth electrode by means of an earthing conductor.

Effective earth connection is sometimes difficult.

(So what did I say about the length of earthing stakes and ground resistance? This is what BS 7430 : 1998 ‘Code of Practice for Earthing’ has to say)

The soil resistivity of the ground is probably the single most important factor in the determination of the type of earth electrode. Rods can only be as effective as the contact they make with the surrounding material. Thus, they should be driven into virgin ground, not disturbed (backfilled) ground.

Many new Thai houses have raised land or sit on disturbed ground.

Where it is necessary to drive two or more rods and connect them together to achieve a satisfactory result, the separation between rods should be at least equal to their combined driven depth to obtain maximum advantage from each rod. In some locations low soil resistivity is found to be concentrated in the topsoil layer, beneath which there may be rock or other impervious strata which prevents the deep driving of rods, or a deep layer of high resistivity. Only a test or known information about the ground can reveal this kind of information. In such circumstances, the installation of copper earth tapes, or pipes or plates, would be most likely to provide a satisfactory earth electrode resistance value.

I learnt that many years ago, when I was installing “clean earths” and filtered supplies. As opposed to “dirty” supplies that would have wreck havoc on the computers rooms / mainframes that I was working on.

As per Australian Regulatory requirements, the Earth Fault Loop Impedance must meet a minimum requirement.

Back to the TT description

Because of this, socket outlet circuits must be protected by a residual current device (RCD) with an operating current of 30 mA

There is a difference between ELCB’s and RCDs / RCBO’s

An Earth Leakage Circuit Breaker is a device with two earth terminals used to directly detect currents leaking to earth from an installation and cut the power. They were mainly used on TT earthing systems before RCDs became common. They have been almost totally replaced by RCDs due to a number of problems.

They do not allow a system to be easily split into multiple sections with independent fault protection, due to the fact that earthing systems are usually bonded to things like pipework.

They may be tripped by external voltages on something connected to the earthing system such as metal pipes, a TN-S earth or a TN-C-S combined neutral and earth.

They introduce additional resistance and an additional point of failure into the earthing system.

Regulation 5.9.4 - Fault voltage operated circuit breakers

These circuit breakers, commonly known in the trade as 'voltage ELCBs', were deleted from the 15th Edition of the Wiring Regulations in 1985, and should not be installed. It is advisable that installations where they are still in use should be carefully tested prior to a change to residual current device protection.

- This is what I believe SafeTcuts are, and Elkangorito makes several references to ELCB’s.in other notes 3/

These were made obsolete in the UK 22years ago

A Residual Current Device is an electrical wiring accessory that disconnects a circuit whenever it detects that the flow of current that is not balanced between the phase (live) conductor and the neutral conductor. The presumption is that such an imbalance may represent current leakage through the body of a person who is grounded and accidentally touching the energized part of the circuit. A shock, possibly lethal, is likely to result from these conditions; RCDs are designed to disconnect quickly enough to prevent such shocks.

The choice of the most suitable RCD for a particular application should take into account Sensitivity:

10mA RCDs offer a high degree of protection against electrocution in an accidental shock hazard situation. They are of particular value in a high risk area where resistances external to the body are likely to restrict the earth fault current flowing through the body to less than 30mA and where 110V supply is being used.

30mA RCDs offer a high degree of protection in an accidental shock hazard situation and are by far the most popular sensitivity used in the United Kingdom.

In a shock situation, the current flowing through the human body at 240V 50Hz could be between 80 and 240mA, depending on the resistance of the body in question. To ensure that there are no harmful physiological effects in such a situation, it is necessary for the RCD to operate within 300mS at 30mA and 40mS at 150mA. As the RCD typically operates well below these times, it clearly more than satisfies this requirement.

100mA and 300mA RCDs are also available, but would not be sensitive enough.

Regulation 5.9.3 - Regulations for residual current devices (RCDs and RCBO’s)

The primary purpose of the residual current device is to limit the severity of shock due to indirect contact. In other words, it will detect and clear earth faults which otherwise would could lead to dangerous potential differences between pieces of metalwork which are open to touch. If the sensitivity of the device (its operating residual current) is low enough, it may also be used to limit the shock received from direct contact in the case of the failure of other measures.

In some cases RCD are designed so that their operating parameters, such as the rated residual current or the time delay, can be adjusted. If such an RCD can be operated by an ordinary person (rather than by a skilled or instructed person then such adjustments must only be possible by a deliberate act using a key or a tool which results in a visible indication of the setting. it appears that Australian Standards fit almost perfectly where other standards may cause problems.

RCDs must never be used as the sole method of direct contact protection (Earthjng), but are invaluable in providing supplementary protection in high risk environments.

A Residual Current Breaker with Overload is a combination of an RCD and a miniature circuit breaker (MCB).

Both RCD’s and RCBO’s will operate in a -25 to 40C temperature zone.

Elkangorito's Other notes taken from his “residential wiring doc”

1/

An individual Earth Leakage protection device (ELCB or RCD) should not protect the entire residential electrical installation. Individual Earth Leakage protection devices are recommended for each Power Circuit/Lighting Circuit. This is because that some appliances like old refrigerators/air conditioners have a high residual earth leakage & can therefore cause nuisance tripping. As appliances become older, residual earth leakage becomes more apparent. Would you want your whole electrical supply to trip because of one appliance? In such situations, people who have their whole house supply protected by one (1) earth leakage device, tend to increase the trip current to overcome this nuisance tripping. This ultimately defeats the purpose of Earth Leakage protection. It usually ends up being turned off or removed.

The usage of RCBOs seems to be alluded to, but not named – I am not aware of their availability in Thailand.

2/.

Only half of the lighting circuits shall be protected by earth leakage devices. In the event of a fire or a similar emergency, it is not recommended that all of the lighting circuits be disabled. How can you find your way out if all the lights trip on earth leakage?

Agree

3/.

Earth Leakage Protection Devices are electronic & hence, are not reliable. They can fail without notice. Also, these devices will not detect a fault if you become connected between ‘active’ & ‘neutral’. It will not trip under such circumstances & you will be electrocuted (although you may not die). Also, many Earth Leakage Protection Devices do not detect ‘half wave’ faults. An example of such a fault is where a hair dryer is used in a bathroom. The hair dryer is being used on a reduced ‘heat’ setting & both the user & the hair dryer come into contact with water. In this situation, some types of Earth Leakage Protection Devices will not detect the fault & therefore will not trip. Ensure that your Earth Leakage Protection Device will protect against ‘half wave’ faults.

A sticker is on the C/Unit warns that RCDs / RCBOs should be monthly tested by pressing the “Test” button (which will simulate a ground fault by bypassing some current) and see if the RCD reacts correctly opening the circuit. If it does not trip, the RCD should be replaced

Also the complete installation should be professionally checked every 10yrs.

I do not know of any cases where someone has been electrocuted and survived… electrocution is fatal. Until fatality happens, it is classed as a severe electric shock!

A RCD/RCBO would detect the hairdryer fault using PME

4/.

An MEN link is crucial for your safety. Also, ensure that your appliances are correctly earthed. DO NOT rely upon Earth Leakage Protection Devices to save your life. They are Secondary to an MEN Link & a correct earthing system.

Provided it has been correctly installed and not been tampered with.

As the saying goes - Do not monkey around with electricity _ or this happens.

http://www.thaivisa.com/forum/style_images...e_types/gif.gif

http://www.thaivisa.com/forum/style_images...e_types/gif.gif

taken Ko Lanta

This is more like it - Meter Thai style, from the vilage I live in. http://www.thaivisa.com/forum/style_images...e_types/gif.gif

http://www.thaivisa.com/forum/style_images...e_types/gif.gif

So how many potential faults... ????

3NI9MA · February 22, 2007

I had hoped "Someone" was going to share his wisdom and reveal the answers....

They are:

The KWH Meter In-adequately secured to the back plate – bent over nails

No HRC “cut-out fuse” to “down-rate” supply - Not in picture!

No colour Identification / discrimination of the incomers - Could be reversed polarity

No IP65 Enclosure (Spray proof from water and Dust proof)

The terminal shield is missing

The outgoing cable size is of a smaller diameter

A screw is missing from the Live terminal

The insulation has perished on the outgoing live

Scenario

Torrential rain – like it does. The concrete pole has the potential to become “live” and track down to earth. Anyone going near is entering a potential hazard zone.

Much the same as the small monkey.

It obviously had bitten into the insulation of the live while grasping the Neutral (Earth) and got zapped.

elkangorito · March 3, 2007

I had hoped "Someone" was going to share his wisdom and reveal the answers....
Sorry 3NI9MA but I didn't know there was a question. Anyway, my comments in blue.

They are:

The KWH Meter In-adequately secured to the back plate – bent over nails.

Probably done by the electricians wife.

No HRC “cut-out fuse” to “down-rate” supply - Not in picture!

This is something of concern to me. Never in Thailand, have I seen a Service Fuse. It is common sense for the energy authority to want to protect their KWH meter with one of these fuses, which should be placed before the KWH meter. Not only that but if the fuse is to BS 1361, it will limit the fault current to as low as 2 000 Amps. This means that you could downrate your circuit breakers from 6kA to 2kA interrupt capacity.

No colour Identification / discrimination of the incomers - Could be reversed polarity.

Unfortunately, an overly common problem here.

No IP65 Enclosure (Spray proof from water and Dust proof).

I think the Seimens KWH meters used here are weather proof (min IP55).

The terminal shield is missing.

The outgoing cable size is of a smaller diameter.

Can Thai electricians work out the current ratings/voltage drops/fault current capacity of cables for given installation parameters?

A screw is missing from the Live terminal.

The insulation has perished on the outgoing live.

Scenario

Torrential rain – like it does. The concrete pole has the potential to become “live” and track down to earth. Anyone going near is entering a potential hazard zone.

Much the same as the small monkey.

It obviously had bitten into the insulation of the live while grasping the Neutral (Earth) and got zapped.

Sign In

Electrician

Recommended Posts

Create an account or sign in to comment

Create an account

Sign in

Recently Browsing 0 members

Announcements

Topics

Latest posts...

Popular in The Pub

ASEANNOW

MORE INFO

POPULAR AREAS

CONTACT US