Electrical safety in Thailand

Electrical safety in Thailand

Postby Ian on Tue May 26, 2009 11:17 am

This topic is is the result of discussions in Prommee's blog "lightning strikes", the hazards, dangers and general incompetence of Thai electricians, coupled with the fact there seem to be no national standards such as the IEE in Thailand.
We can start with the consensus that an RCCB should be installed before all else.
Then we can discuss cable sizes and types, joints, junctions, bonding and Earths. 2-wire and 3-wire systems, efficiency categories, water heaters, aircons, appliance flexible leads and so on.
This is a topic where the less knowledgeable can ask questions and where the more knowledgeable can give answers and advice.

My first piece of advice is before using a Thai electrician is to ask if he knows what an ELCB or RCCB is, and what is the difference, if he cannot answer look elsewhere :lol:
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Re: Electrical safety in Thailand

Postby Sean Moran on Tue May 26, 2009 12:00 pm

I'd guess that ELCB and RCCB refer to circuit-breakers. The new kind apparently cut out so quickly that the electrocutee barely feels the jab, although I've never tried one.

I did some re-wiring of some fluro lights another sparkie in the ceiling of a shop in Bang Kapi in 2005. Compared to the hazards you might find in a roof here in Perth, the existing system (maybe 20 or 30 years old?) was a fairly pvc-tape infested arrangement, but everything seemed to work okay. Not sure on the GPOs because we ran all new ones as part of the renovation but the one that I've heard about most is the HWS systems that aren't grounded, so if you're having a hot shower and something shorts out, it earths through the water and you.

If the power cable coming out of the HWS is three core, then chances are that those are Active, Neutral, and Earth, if I remember. If it only has two cores (like lights in the ceiling sometimes - not sure???) then there's no earth and that's said to be a hazard. :roll:
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Re: Electrical safety in Thailand

Postby Ian on Tue May 26, 2009 12:16 pm

Sean Moran wrote:I'd guess that ELCB and RCCB refer to circuit-breakers. The new kind apparently cut out so quickly that the electrocutee barely feels the jab, although I've never tried one.

I did some re-wiring of some fluro lights another sparkie in the ceiling of a shop in Bang Kapi in 2005. Compared to the hazards you might find in a roof here in Perth, the existing system (maybe 20 or 30 years old?) was a fairly pvc-tape infested arrangement, but everything seemed to work okay. Not sure on the GPOs because we ran all new ones as part of the renovation but the one that I've heard about most is the HWS systems that aren't grounded, so if you're having a hot shower and something shorts out, it earths through the water and you.

If the power cable coming out of the HWS is three core, then chances are that those are Active, Neutral, and Earth, if I remember. If it only has two cores (like lights in the ceiling sometimes - not sure???) then there's no earth and that's said to be a hazard. :roll:


After fitting an RCCB which tripped at 30mA imbalance, I demonstrated it to a disbelieving Thai electrician by poking a nail into the live terminal of a socket. I got a mild jolt and the house was plunged into darkness.

Incidentally, with many people it is not the electricity that kills but the physical shock. Electricity normally kills by cooking ;)
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Re: Electrical safety in Thailand

Postby Sean Moran on Tue May 26, 2009 12:22 pm

That's a very gutsy thing to demonstrate. :cheers:

Regarding the physical shock, do you mean the muscular reaction of particularly the heart and vital organs to the stimulation? That does tend to fit fairly well with the one time in my life I was ever electrocuted, and it wasn't from an AC outlet but a capacitor on a line printer I was fixing at an office in town. When I got the jolt, I had the printer in my hands and the shock made me throw it across 4-5 metres of open-plan office barely missing the telephonist in the corner. It was the physical shock that almost killed her, I'd say. :lol:
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Re: Electrical safety in Thailand

Postby Ian on Tue May 26, 2009 12:47 pm

Sean Moran wrote:That's a very gutsy thing to demonstrate. :cheers:

Regarding the physical shock, do you mean the muscular reaction of particularly the heart and vital organs to the stimulation? That does tend to fit fairly well with the one time in my life I was ever electrocuted, and it wasn't from an AC outlet but a capacitor on a line printer I was fixing at an office in town. When I got the jolt, I had the printer in my hands and the shock made me throw it across 4-5 metres of open-plan office barely missing the telephonist in the corner. It was the physical shock that almost killed her, I'd say. :lol:


What I mean is this, if I was to fire a gun next to your ear without you knowing it, the shock induced adrenaline rush would kill some people, or at least give them palpitations :lol:
in my case it was not particularly gutsy, most electricians become accustomed to shocks. If I don't have a tester handy I would often swipe my finger fast across a wire or terminal to see if it was live. Many times I have been called by a customer complaining that a particular device was giving them shocks, shocke which I could not detect myself but needed a neon to verify it was not their imagination.

Electricity usually kills by cooking the living flesh. Here are some extract from American executions.

The history maker was William Kemmler of Buffalo, New York. Kemmler was guilty of butchering his mistress with a hatchet. A group of doctors and reporters gathered for the historic occasion. Kemmler was jolted for seventeen seconds. It failed to kill him. Kemmler was unconscious but still breathing. The embarrassed prison officials electrocuted him again for seventy seconds. Kemmler thrashed and convulsed as the electrodes seared his head and arms, filling the room with the smell of burning
flesh. Some witness fainted, while others fled the room. The killing took eight minutes.

William Taylor was slated for execution on July 27, 1893. The first jolt of electricity caused his legs to stiffen with a force so great that they tore loose from the chair's ankle straps. Like Kemmler, Taylor was still alive. When the executioners attempted to send a second charge through Taylor's body it was discovered that the generator in the powerhouse had blown. Taylor was removed from the chair and placed on a cot. Officials kept him alive with chloroform and morphine so that he could be officially killed by an active current. An hour and nine minutes later Taylor was returned to the chair and given a more than adequate charge.

In 1890 Auburn State Prison used the first electric chair to execute a convicted murderer, using Westinghouse alternators. "Kemmler was strapped into the chair on August 6, 1890. The first jolt
of alternating current lasted 17 seconds. Kemmler continued struggling. A second jolt lasted more than a minute, until smoke was seen rising from the body.

How It Works: The prisoner is shaved, strapped to a chair, and fitted with electrodes attached to conductive sponges--one on the head, one on the leg. The prisoner is then hooded. The executioner pulls a switch, and 2,000 volts race through the prisoner's body as the internal body temperature approaches 140 degrees.
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Re: Electrical safety in Thailand

Postby Ian on Tue May 26, 2009 8:43 pm

Noaksy wrote:Different injuries are possible from an electric shock but I believe, as Sean said, that death caused by the contraction of the heart is the most common cause. A severe electric shock usually causes muscles to contract. With Alternating Current (AC), this can make it difficult to disconnect from the contact point. Burns usually occur on the body at the point of contact. Internal burns are possible but with AC, fibrillation of the heart occurs at much lower current flow. This fibrillation can cause the heart to stop.

Ian, the burning you quoted may be the case with state sponsored electrocutions but in a domestic or work type situation, people are not strapped to a chair and the point of contact is usually a small one; the hand, for example.

Here are a couple of good reads on the topic:

http://www.pat-testing.info/electric-shock.htm
http://www.dhyansanjivani.org/diseases/ ... _shock.asp


Human reactions to electric shock are very varied, your links are valid for most people, but definitely not for me or many others I know. Skin resistance, subcutaneous fat, acquired tolerance are all factors which can cause variations. I have had numerous shocks in my life, at one time a daily event :D But only two stand out in my mind, one was a 10amp, 2000v secondary winding on a transformer I had just built, I was checking the offload voltage with my AVO. I cliped to one side, then the other, no problem, then I used both hands together to remove the clips :lol: According to observers I shot backwards about 8 feet and ended upright against the wall, no pain but I was puzzled why I was against the wall.

The second occasion I was fooling around with a three phase mercury arc rectifier, I was kneeling on a steel bench to get at it and waving a strong magnet around to demonstrate how is moved the discharge paths. The magnet suddenly clamped to one of the AC terminals and I promptly from that kneeling position did a complete backwards somersault on the floor. Again no pain, but puzzlement about how i got there. :lol:

Most normal shocks give me a buzz, the brain seems clearer, things are more vivid. I have met some electricians almost addicted to this. It is fun to pass enough pulsed current from arm to arm to make the muscles tense in rhythm with the pulses, I built a machine to do just this, about 100 volts at a few milliamps does the trick.

Anyway, all this is really off topic :cheers:
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Re: Electrical safety in Thailand

Postby prommee_NE on Wed May 27, 2009 1:18 am

Okay...so now we know the dangers of electrocution...time to get back to the original topic then...how to defend oneself, as best as possible against it....and I don't mean the electric chair! In short Electrical Safety.

I have written too much already below...so I will provide my experiences in installments...hope you don't mind...gives people the chance to comment and ask questions as we go along.

My background is as an aircraft avionics apprentice, followed by a degree in Electrical/Electronic Engineering and too many years as a software consultant ...not the best person to give advice about domestic house electrical safety...I admit that and I am hoping that a qualified domestic electrician will be on the forum and advise correctly. If anything, I think I am overkill...but may be killed in thinking that (SJB... I read too many of your posts!) I can only give you the experiences that I have had in Thailand, what I have done and how it has progressed...and how it may have been better done (through Expert posts please) ....I expect you all to realise that this is totally unofficial and in no way should you use this information as correct and cite me following an electrocution...Caveat over with.

Firstly...when I went to the Electricity Board office in my local town and asked for 50 Amps they looked at me dumbfounded...why the hell do you want 50A they said...well my shower is rated at 30A and if I have a shower with the fridge on and my wife is using the washing machine and ironing...50A is pretty much low estimate of current requirement (normally an average house in the UK is on 100A minimum). Okay this was ten/eleven years ago and I was a bit naiive. The information I received was that a village Thai house gets 3A, a Farang/Town house 15A and a Garage can get 30A. I was a bit confused and questioned a little...through my wife. Eventually I was told that the rating given is about 1/3 of the actual rating available...Swiss standards are triple safe so "we" (he Thai Electricity Board) can increase them by three. Upgrading in rating is a significant cost...the house (actually a 100 sqaure metre bungalow at the time) was being used for 2/3 months a year...okay do as the Romans do and so be it. 15 Amps (45) will do

Next was building inspection time...After we married, I agreed that my wife's savings could be put on having a house in her village in NE Thailand...she paid for the house and I paid to get us there and back (and the house in Europe)...pretty good deal really. Inspection of brickwork, plumbing and general interior was very good...actually, I was impressed right up until I saw the wiring...not the wiring visible (they are very good at general laying and positioning of lights, switches, sockets etc .) but the hidden wiring in the ceiling...It was a disaster! I spent the month going through electrical shops in NE Thailand, trying to get to grips with how to make the house safer...What I found was some good stuff and some not so good stuff. I let it go until we built a 50 square metre inside kitchen extension and a 60 square metre outside kitchen/patio area. My wife wanted an Oven, Hob and kitchen sockets to supply power for kettle, toaster, mocrowave etc. Also she wanted to have a utility room for ironing and washing. ( I guess she spent far too many years in the West!)

Wow! I was just slightly getting overwhelmed here...Rubbish electrics (even the incoming was joined with tape ...50A...all I could think was fire...fire) and the pressure of the wife wanting something as she expected in England. Naturally she did not get English standards...but the standard she got, I believe is safe and although a compromise may be beneficial for all Farangs. (Especially when people tell me where I went wrong and give advice about how to correct it)

Before I get going with the nest installment...I have a question. In the Lightning topic, people mentioned RCCB's, whereas I mentioned RCD's. Some may be confused by the terminology...I am one of them. I thought that RCCB's referred to individual circuit 'Residual Current Circuit Breakers' within a Consumer unit. I have never seen these in NE Thailand, I have only seen single 'Residual Current Devices' as a single circuit breaker in a Consumer Unit (usually on the right hand side just to the left of the master circuit breaker). The advantage of having individual RCCB's per circuit means that some items (freezer etc) do not need to have them and will continue to function. The RCD I refer to will kill all power to all circuits fed from that Consumer Unit. Can someone confirm the terminology for me.

This is only an introduction...next, I will explain why I used radial circuits in my house as opposed to the UK norm of using ring circuits. Following this, I will explain why I used two separate consumer units in the house and why I decided to have an earth for the Kitchen and utility rooms...and why I left the rest of the house two-wire (except for the bathrooms).

I guess a qualified electrician is going to have a field day with me...

Edit: Sorry about the typo's...hope to improve in future but I am sue you will all understand the 'gist' of the post without me having to go through it and correcting them. I'd blame the keyboard but...in the context of this topic it is like blaming the RCD for not tripping when you are being 'zapped'.
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Re: Electrical safety in Thailand

Postby Ian on Wed May 27, 2009 10:41 am

In reply to Prommee, it seems that both Noaksy and myself are ex-professional electrical engineers. I stopped being "professional" about 35 years, when I became a Physics teacher. However, in vocational classes I continued to teach domestic installation work as well as "moonlighting " a bit ;) In particular I did all the installation work in my house and the one used by my son, both built by me using subcontractors.
So this is my level of expertise, I'm sure Noaksy will be similar vintage if he remembers mercury arc rectifiers :lol:

I am going to start from basics, Ring circuits. These were a government and Council Estate ploy to reduce the amount of copper, and hence cost, but in my opinion it has many disadvantages and dangers.
First for those unfamiliar with the term, a "Ring Main" to use the common term is where every outlet is joined to others on either side such as a complete loop of wire goes from the consumer unit and back again.
There is no electrical justification for a ring main, it was devised to cut costs and save copper.... for a full discussion of this and the hazards see http://en.wikipedia.org/wiki/Ring_circuit
The official name for a non ring main is "radial", but I prefer to use the word "Star" as it is to me more description if many such radials are used.
A radial is a number of outlets wired in line, normally for simplicity the same gauge wire is used for all although some may use a decreasing wire size as they move further from the consumer. A to B 4mm, B to C 2.5mm.
Let me here introduce the term "Diversity Factor", this is another cost cutter, it is based on the assumption that all the outlets will never be fully loaded all at the same time, this means you can use smaller cables and fuses. In the UK this is normally taken as 40%, so you can wire for just a 40% load. Again I feel this can be a dangerous assumption, see Prommee's example of a wife at work :lol:

So when working for myself I always use a "star" layout and with a personal gimmick. This gimmick is I have each room on its own radial feed but this radial also supplies one outlet in another room. There is a logic to this, if I am working on the outlets to one room (repair or extending), I can turn off the power to that room but one socket stays operational, handy to plug in a lamp or electric drill. It does mean that my consumer unit is large 8 outlets, so in fact I use two, one for power the other for lighting. My house has 7 rooms including bathrooms so with a seperate feed to the immersion heater it just fits nicely.

I will pause here to give my finger a rest and to allow for comments, if any :cheers:
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Re: Electrical safety in Thailand

Postby Ian on Wed May 27, 2009 2:27 pm

Continuing my discussion, there has been much concern expressed at joints made by twisting bare wires together, then taping over, in fact this is an approved method if done correctly (as I was taught in The Royal Signals :) )When wires are joined there are two criteria, one is electrical restance, the other is mechanical strength, a well made twisted joint does both.
The main problem with copper wire is corrosion leading to a a high resistance joint, overheating and risk of fire. A good electrical joint must have maximum copper to copper contact, and under pressure so as to exclude corrosion agents, such as air and water. Another factor is to solder or not such a twist joint, tests show that initially a soldered joint has lower resistance, but over time it becomes higher than an unsoldered joint. The unsoldered joint improves with time due to cold metal diffusion under pressure.
There are several methods of making a good twisted connection, none since the 70's are approved by the IEE, although still allowed in America and the army, as the IEE are a bunch of old women , I follow the army :lol:
The best method for speed, in my opinion is the "Screwit", this is a thimble shaped ceramic device with an internal coarse thread. Many people twist the wires together then screw on the screwit, this is wrong. The correct way is to hold the two bare wires together and parallel, then screw it on, this not only twists the wires together but maintains the pressure. Wrap the entire screwit and cable in PVC tape and you have an excellent joint.
IEE asks for crimp connections (similar to what you see in a car), unless you have the proper tool and crimp glands these have a high failure rate, either from over crimping or under crimping.
So both twisted wire joints and crimp joints require some skill and practise.
So for the novice I would suggest "line taps", "Junction boxes" or Ceramic or plastic "Chocolate" terminal blocks.

More on these next time.
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Re: Electrical safety in Thailand

Postby stilljustbrowsing on Thu May 28, 2009 1:20 am

Hi guys, and prommee, It is I that is supposed to be "browsing" :lol: :cheers:
If you are all serious about helping others, stop using acronyms! Rule No. 1 for "human factors." (abbreviations are also to be avoided)
For example, RCCB can mean many things, but in terms of elecricity we have "residual current circuit breakers" and "reverse current circuit breakers."
RCD is a reverse current device.
For those that want to know what acronyms mean, mayI suggest you "web search" acronym finder.
BTW Ian, I am (I think) as crazy as you. When I want to find out which HT (high tension) lead is failing, I use the BACK of my hand as a test unit! (or else I just wait for darkness and see which one is starting to glow!)
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