Please help me understand Thai house electricals...

[Muhendis]

WPCOE

Definitely armageddon setting.

[Muhendis]

WPCOE

A phase tester is only a screwdriver with a neon bulb and a 1 megohm resistor in the translucent plastic handle.

[Phuket electrician]

'A phase tester is only a screwdriver with a neon bulb and a 1 megohm resistor in the translucent plastic handle.'

DO NOT TRUST THIS TOOL!

It will illuminate on both L&N

Please if you know nothing of electricity DO NOT GIVE DANGEROUS ADVICE!

[Phuket electrician]

DO NOT TOUCH THAI ELECTRICS UNLESS YOU UNDERSTAND THE POTENTIAL RISK!!

[Muhendis]

If neutral is connected to earth then please explain how the phase tester will light up.

[Phuket electrician]

With due respect the 'tool' in question is a rudimentary voltage indicator. It will only indicate the presence of 'voltage'. A Thai electrical installation is held together with installation tape because of the installation method. And it is not uncommon for circuits to be unprotected by a 'fuse' - immaterial here.

Live will have a potential difference of somewhere between 0-220 volts

Neutral may have a potential voltage to 'earth' for example 0-50 volts the voltage tester will illuminate to indicate the presence of 'voltage'.

If this cable is tested before any other the inexperienced will assume this to be the live. And by a process of logic the other cable to be the neutral. Clearly not the case.

A very dangerous scenario for a bare foot human being about to grab hold of a live cable protected by a dodgy 30 A fuse or non at all. Worst case scenario electrocution!

The point is one of safety. A voltage indicator can be a lethal tool in the hands of an amateur. Wouldn't you agree?

Best regards, TIT it is wise to be cautious and look before one leaps.

Edited September 5, 2013 by Phuket electrician

[khunPer]

@wpcoe

»IF I already have a MEN setup, why do I get tingles from my computer case?«

Because your computer has a transformer; that makes a so-called “galvanic separation” from the 220 volt primary mains power to your secondary computer electronics. Any current leaking to chassis (the metal cabinet) after the transformer, will not find it’s way to earth, unless your chassis is earthed. As the computer electronics are galvanic separated an ELCB or like will not measure any leak to chassis in the secondary electronics. A bit technical, but in short terms: you will need your computer to be connected to a proper earth.

If you intend to use the roof steel as earth, you may like the device I described in an earlier post for the OP – the extension plug with a surge protection and earth LED-tester (I know of brand name Elektra, there may be others available).

In general, I will say: yes, I have seen many exiting – even amazing – electric installations in Thailand. However, where I live there are plenty of good electricians available, knowing what they are doing and doing a fine and safe job using quality components, exactly after a detailed drawing layout.

And for water heaters (talking about devises for hot water in bath or kitchen) – and I do not say, that it does not exist – I have never seen one with a 2-pin fixed wire, only models for “hard-wiring” with L-N-E (Live-Neutral-Earth connections).

@Phuket electrician

My simple screwdriver phase checker only lit on Live – even the pro electricians borrowed it for checking if their own pro equipment was not handy, when doing the house – is there something wrong with my Neutral?

[Phuket electrician]

It's an indicator not an instrument for measuring voltage. if you see a beautiful girl in a nice dress - doesn't mean she's female.

Look at these numbers

200 milli Amps is a lethal current for a human

Normal conditions 220 v / 1350 ohms = 160 milli Amps electric shock

Damp human 220 v / 1000 ohms = 220 milli Amps electrocution

Wet human 220 v / 500 ohms = 440 milli Amps

Wet human 100 v / 500 ohms = 200 mill A

The point being TIT there are no registered sparks. The industry is not regulated. Equipment is not regulated.

May I suggest it is unwise to touch electrics here for safety reasons.

Best regards.

[wpcoe]

Okay. I have a flat screwdriver. I can just stick that in an outlet and see if it lights up?

Seriously, folks. I am NOT about to do ANYthing with the electrics myself. I'm just trying to learn how it SHOULD be done so I can find someone and tell them what I want done, and then watch them to see if they are doing it.

My goal is to (a) get the necessary outlets and devices earthed/grounded and (b ) put some RCBO type switch in that will trip at a milli-amp level vs at a mutli-amp level.

I do continue to learn from these posts, so please continue to post even some of the more technical explanations. SOME of it will sink in, and more importantly other folks following this thread may get some valuable lessons.

Went to HomeWorks in S.Pattaya this evening: no RCBOs of any type, any brand. Guess I need to head further into town to HomePro. I was simply too tired this evening to do it. Crossy, if you can give me a specific part # for that RCBO, that would be nice. Would eliminate a potential misunderstanding. e.g The HomeWorks guy tried to sell me a different brand of main switch -- not an RCBO, just a plain black switch like I have now -- and told me it was the same thing as a Square D RCBO.

[Phuket electrician]

You don't really need any of that stuff. If you need work doing get a pal to recommend someone.

[jackflash]

Neeranam,

Somehow my previous post disappeared...

> Higher voltage means lower current if R = V/R (Ohm's Law).

You are confusing Ohms law with the Power Equation P = E x I.

Voltage pushes current through Resistance. A Higher Voltage means a higher Current will flow.

> So in the USA, lower voltage means higher current and the current is what kills people, I thought.

Current kills, but it is the voltage which causes the current.

If you touch 240 Volts you will receive approx twice the Current that 110 Volts would give.

Edited September 5, 2013 by jackflash

[Crossy]

@wpcoe please post a good photo of your main switch so I can confirm the information below:

The Schneider / Square-D device you need is QO245MBGX30 - 2 pole 45A/30mA plug-in RCBO, Thai Interelectric have these catalogued at 4,800 Baht. Ouch!

Not sure how current this catalogue is mind http://www.thai-inte...residential.pdf (Page 18), print that page and take it with you.

This is the easiest solution as you simply replace the incoming 45A breaker with this device.

Btcino make compatible plug-in RCBO units which may be cheaper, but I don't have their catalog to hand so i cannot give a part number.

Whatever you buy it needs to have a 'Test' button, a dead giveaway that you have an RCD or RCBO.

ALTERNATIVELY (and cheaper).

You could get a plain DIN mount RCD and put it in your incoming supply before the consumer unit, this would require re-routing your incoming supply wires (sometimes easier said than done) and a small plastic enclosure, both RCD and plastic box (with a moulded DIN rail) are available at Homepro. You can get away with a cheaper RCD rather than an RCBO in this instance as you retain the existing main switch (MCB) which provides over-current protection, just ensure that the current rating of the RCD is bigger than 45A.

[NCC1701A]

Here is something to think about.

Electrons flow from positive to negative (ground). They are always looking for a path to ground.

Electrons don't flow if there is no path to ground. The "potential" for electron flow is always present.

Electrons will follow the "path of least resistance". If you are the "BEST" path they will flow through you to find ground.

If you have a properly grounded appliance (or any electrical device) that is malfunctioning, the ground connection will cause the electrons to flow in a very large amount and the circuit breaker for that plug in your house will "trip" or open to stop the UNCONTROLLED flow of electrons to ground.

If there is no ground connection with a malfunctioning device, YOU COULD become the path to ground.

Because you maybe wearing shoes or standing on wood floors your "ground potential" changes. If you were completely grounded (holding a wire that was connected directly to the earth, there is a very good chance you will die as the total "load" would flow through you and possibly kill you before a circuit breaker for that plug would trip.

If you are in a house and you know your ground connections don't exist, and want to add a extra layer of safety, connect #4 gauge wire to the ground terminals on the back of your washer and drier (and other large appliances) and run the wire directly outside to a copper rod driven 8 feet into the ground. This would "bypass" funky Thai electrical wiring and provide a additional ground for your heavy appliances where water and humans interact.

[Muhendis]

Phuket Electrician,

I couldn't agree with you more. Any tool in the hands of an amature could be lethal, I note our friend wpcoe has stressed several times that he has no intention of doing any electrical work himself so I think he will quite likely not get hurt....unless, of course the Thai electrician screws up.

Further information about neon phase tester screwdrivers (for the technically curious).

The striking voltage for neon is about 90v and the hysteresis is about 50% (I do not use precise figures because of slight variation between neon bulbs).

So the neon bulb will not extinguish until the voltage across it has reduced to <45v (63.6v rms).

The ac voltage would need to be 90v peak (180v p-p 127.3v rms) before the neon would light.

Once the neon lights the current that flows through the bulb needs to be limited to a safe level. To do this a 1,000,000 Ohm (1M Ohm) resistor is included in series with the bulb.

When checking the 220v live wire the current flowing, disregarding the human body resistance, would be (220v rms - 63.6vrms (from 45v pk)) / 1M Ohm = 0.16mA.

Personally when I buy a new phase tester I first check the resistor.

If the phase tester lights up on both the live and the neutral (yes they must both be checked) then there are problems that need expert attention.

Footnote:

Over 40 years ago I had an oscilloscope that used neons in the timebase. Thank goodness technology has moved on........

[David48]

It's an indicator not an instrument for measuring voltage. if you see a beautiful girl in a nice dress - doesn't mean she's female.

Actually, logicially it's ... if you see a beautiful girl person in a nice dress - doesn't mean she's female.

If you are going to use a metaphor ... firstly, get it correct and then make it relevant ... give it a bit of spark ...

[Muhendis]

Hey David48, you're a bit of a live wire aren't you?

[Crossy]

Ok children, enough

Back to the subject at hand.

I agree with the above sentiments to call in a professional electrician, if we were in the West that would be the correct (and in some countries the only) option.

But, we are not in the West, we are in sunny Thailand where professional domestic sparkies are as common as hen's teeth. There are many good Thai sparkies, but they're all on major projects or earning pots in O&G and are unlikely to be interested in house bashing for the pittance available.

So, here we are trying to give advice to those who need it.

Domestic wiring is not rocket science, there are after all only 3 wires, how wrong can it go? Very wrong as we see from the sheer volume of posts in this forum.

All the bits required to provide a safe and professional installation are readily available here. The correct solutions are in that PEA document Groundwire.pdf in Thai.

So let stick to correct solutions, no bodges like rubber mats please. The advice to pull the plug until the issue is sorted is good.

[jackflash]

A number of posts have recommended using a neon tester to check your earth connection.

In my mind this is bad advice as theses testers measure Voltage rather than Current (and rather crudely at that).

Even using a good multimeter to measure the voltage can be very misleading.

There is an effective test which involves passing current via a large lamp into the earth wire and measuring the voltage rise against a temporary outside Earth stake.

(I hesitate to go into more detail as it could be lethal if attempted by an amateur).

The best way however is get an Electrician to measure the actual earth resistance using a specialised instrument (a Megger).

Unfortunately it takes skill and the right equipment to do this test properly

A good technical reference is here: www.biddlemegger.com/biddle-ug/GettingDownToEarth-MC.pdf

The bottom line is, don't rely on a simple neon tester to check your earth wiring.

Edited September 6, 2013 by jackflash

[wpcoe]

@wpcoe please post a good photo of your main switch so I can confirm the information below:

The Schneider / Square-D device you need is QO245MBGX30 - 2 pole 45A/30mA plug-in RCBO, Thai Interelectric have these catalogued at 4,800 Baht. Ouch!

Not sure how current this catalogue is mind http://www.thai-inte...residential.pdf (Page 18), print that page and take it with you.

This is the easiest solution as you simply replace the incoming 45A breaker with this device.

Btcino make compatible plug-in RCBO units which may be cheaper, but I don't have their catalog to hand so i cannot give a part number.

Whatever you buy it needs to have a 'Test' button, a dead giveaway that you have an RCD or RCBO.

ALTERNATIVELY (and cheaper).

You could get a plain DIN mount RCD and put it in your incoming supply before the consumer unit, this would require re-routing your incoming supply wires (sometimes easier said than done) and a small plastic enclosure, both RCD and plastic box (with a moulded DIN rail) are available at Homepro. You can get away with a cheaper RCD rather than an RCBO in this instance as you retain the existing main switch (MCB) which provides over-current protection, just ensure that the current rating of the RCD is bigger than 45A.

Couldn't get a good straight on photo, because the flash washed out the photo, so here's a composite of photos from above & below:

I will give some thought to a separate RCD before the box, but honestly, I'm looking to keep this simple (K.I.S.S.) because the fewer things to alter, the lower the chances of it being messed up. I like the idea of just swapping out the current switch for an RCBO. Square-D to Square-D is even more appealing.

Thanks for holding my hand through this. It's a sign of our times, I guess, that I trust an anonymous person on the internet whom I've never met, than a supposed "professional electrician" in Thailand.

[Crossy]

If you can get the Square-D device I mentioned earlier it should be a straight swap.

Your man will have to disconnect at the meter so make sure he puts it back the right way round (mark the wires with tape).

[krisb]

@wpcoe please post a good photo of your main switch so I can confirm the information below:

 

The Schneider / Square-D device you need is QO245MBGX30 - 2 pole 45A/30mA plug-in RCBO, Thai Interelectric have these catalogued at 4,800 Baht. Ouch!

 

Not sure how current this catalogue is mind http://www.thai-inte...residential.pdf (Page 18), print that page and take it with you.

 

This is the easiest solution as you simply replace the incoming 45A breaker with this device.

 

Btcino make compatible plug-in RCBO units which may be cheaper, but I don't have their catalog to hand so i cannot give a part number.

 

Whatever you buy it needs to have a 'Test' button, a dead giveaway that you have an RCD or RCBO.

 

ALTERNATIVELY (and cheaper).

 

You could get a plain DIN mount RCD and put it in your incoming supply before the consumer unit, this would require re-routing your incoming supply wires (sometimes easier said than done) and a small plastic enclosure, both RCD and plastic box (with a moulded DIN rail) are available at Homepro. You can get away with a cheaper RCD rather than an RCBO in this instance as you retain the existing main switch (MCB) which provides over-current protection, just ensure that the current rating of the RCD is bigger than 45A.

 

Couldn't get a good straight on photo, because the flash washed out the photo, so here's a composite of photos from above & below:

 

SquareD_switch.jpg

 

I will give some thought to a separate RCD before the box, but honestly, I'm looking to keep this simple (K.I.S.S.) because the fewer things to alter, the lower the chances of it being messed up.  I like the idea of just swapping out the current switch for an RCBO.  Square-D to Square-D is even more appealing.

 

Thanks for holding my hand through this.  It's a sign of our times, I guess, that I trust an anonymous person on the internet whom I've never met, than a supposed "professional electrician" in Thailand.  

I don't know a lot but to me those pics look very 1950s.

[bunnydrops]

In the states now, the ground is connected to the rebar in the footing. No more rods or ones cut short because the ground is too hard. I was told once that the reason you have more chance of dying by electrocution is because you can't let go, where as with 220/240 you are more likely to be kicked off--true?

I have one question. The wires used here in Thailand look smaller than the ones we use in the states. There the call outs are 12/3 10/3 etc. What is the average size of the wire for say lighting and the call out.

[Neeranam]

Neeranam,

Somehow my previous post disappeared...

> Higher voltage means lower current if R = V/R (Ohm's Law).

You are confusing Ohms law with the Power Equation P = E x I.

Voltage pushes current through Resistance. A Higher Voltage means a higher Current will flow.

> So in the USA, lower voltage means higher current and the current is what kills people, I thought.

Current kills, but it is the voltage which causes the current.

If you touch 240 Volts you will receive approx twice the Current that 110 Volts would give.

I remember P=IV

I=V/R so I see what you're saying. But, what about those power lines - don't they make them high voltage to reduce the current and thereby reduce power loss?

[David48]

In the states now, the ground is connected to the rebar in the footing. No more rods or ones cut short because the ground is too hard. I was told once that the reason you have more chance of dying by electrocution is because you can't let go, where as with 220/240 you are more likely to be kicked off--true?

I have one question. The wires used here in Thailand look smaller than the ones we use in the states. There the call outs are 12/3 10/3 etc. What is the average size of the wire for say lighting and the call out.

Couple of things.

As for cable size, I'd love to know for sure what they use in Thailand.

In Australia we are metric so refer to sizes in millimeters (mm).

For the power circuit Australia uses 2.5mm twin (live and neutral) and earth, for the lighting circuit 1mm

Most power use comes from heating. As heating is not required much in Thailand then maybe they try and get away with smaller sized cable. Stuff that uses a lot of power are hot water heater (storage or instant), toaster, kettle, air-cons that 'plug-in', big TV's, hair dryers, washing machines that heat their own water ... those type of appliances.

Older Thai style did not use a lot of those things, hence don't need the larger capacity cable.

As for the voltage and electrocution ... both voltages (actually the amperage) will kill you. The bodies mucles rely on electricial impulses to fire and control them. When a passing electrical current disrupts and makes the muscle contract and not release ... holding onto the bare wire ... that's when you die.

I was, and maybe many electricians were taught that if there was any chance the metal surface was live to touch with the back of the hand as the natural contraction of the hand and arm then to repulse away.

All my experiences of wiring are from Australia ... but some principles are universal.

[krisb]

I've noticed sparkys connecting their earth wire to our steel studs at work. This I take it only works because it's steel stud? Timber studs wouldn't work because it's not conductive correct?

I think the idea of earthing through the slabs re bar is a good one. Crossy, what you think?

[Crossy]

Timber is a good insulator unless it's wet, no good for earthing.

Grounding to the structural steel works well, our steel work gives an earth resistance of a few Ohms, certainly as good as the rod we have as well. We are on pretty damp ground mind. Google 'Ufer ground' for more information.

I'm not sure how a Thai inspector would react to an Ufer ground in a new home installation, ours looked for a visible rod.

Grounding to wall studs may or may not be effective because they're not in direct contact with the building steel.

[khunPer]

In the states now, the ground is connected to the rebar in the footing. No more rods or ones cut short because the ground is too hard. I was told once that the reason you have more chance of dying by electrocution is because you can't let go, where as with 220/240 you are more likely to be kicked off--true?

I have one question. The wires used here in Thailand look smaller than the ones we use in the states. There the call outs are 12/3 10/3 etc. What is the average size of the wire for say lighting and the call out.

Couple of things.

As for cable size, I'd love to know for sure what they use in Thailand.

In Australia we are metric so refer to sizes in millimeters (mm).

For the power circuit Australia uses 2.5mm twin (live and neutral) and earth, for the lighting circuit 1mm

Most power use comes from heating. As heating is not required much in Thailand then maybe they try and get away with smaller sized cable. Stuff that uses a lot of power are hot water heater (storage or instant), toaster, kettle, air-cons that 'plug-in', big TV's, hair dryers, washing machines that heat their own water ... those type of appliances.

Older Thai style did not use a lot of those things, hence don't need the larger capacity cable.

As for the voltage and electrocution ... both voltages (actually the amperage) will kill you. The bodies mucles rely on electricial impulses to fire and control them. When a passing electrical current disrupts and makes the muscle contract and not release ... holding onto the bare wire ... that's when you die.

I was, and maybe many electricians were taught that if there was any chance the metal surface was live to touch with the back of the hand as the natural contraction of the hand and arm then to repulse away.

All my experiences of wiring are from Australia ... but some principles are universal.

Same as Australia and continental Europe, square millimeter – i.e. in newer installations 1,0 to 1,5 (6 to 10 amp) for lighting; 2,5 to 4,0 (16 to 32 amp) for water heaters etc.

Modern inverter air cons uses from aprox 500 W; most flat screen TVs between 150 and 400 W (plasma) – the power users in modern household installations are (apart from huge air cons and sauna) mainly hot water heaters, washing machines w/ heater and kitcen stuff.

Older Thai installations may be a single 6 amp or 10 amp (just like oldtime European installations).

[jackflash]

Neeranam,

> .... I see what you're saying. But, what about those power lines - don't they make them high voltage to reduce the current and thereby reduce power loss?

Yes, of course. Higher voltage means lower distribution current and thinner wires.

But this is irrelevant to the severity of the shock you get when you touch a live conductor.

Higher volts mean more current through your body.

While the current available in the household mains is many tens of Amps, the current through your body is decided by the mains voltage and the resistance through your body to ground. It's not the thickness of the conductors in your house which will decide if you are electrocuted or not.

It only takes a very small current to kill you. Much, much less current than that which the power system can provide.

Edited September 7, 2013 by jackflash

[jackflash]

Bunnydrops,

> I was told once that the reason you have more chance of dying by electrocution is because you can't let go, where as with 220/240 you are more likely to be kicked off--true?

My recollections was it was more an issue of AC v/s DC.

DC causes your muscles to freeze, while AC causes them to vibrate.

With luck you'll be thrown clear with AC.

See "War of Currents" http://en.wikipedia.org/wiki/War_of_Currents

[jackflash]

The problem with using Rebar as an earth is that there can be no guarantee of how much of the rebar you are actually connected to.

A rebar mat can be an excellent earth or a lousy one depending on whether the sections of the mat were originally welded together.

Edited September 7, 2013 by jackflash