Domestic Electrical Wiring

[elkangorito]

Just something I found recently whilst surfing the net;

Volume 1 Issue 2, 4th Quarter 2003

Interview with Mr. Somsak Nitisaringkarin

Director, Standard and Safety Department

Provincial Electricity Authority (PEA) Thailand

What are the latest rules/regulations that PEA has implemented and why?

A new regulation that will take effect from 1 October 2003 is the installation of a grounding system for all new electricity users. This regulation is applicable to residential, commercial and industrial buildings and other business centres. This ruling does not apply to residential users outside the municipal area or in rural areas with less than 15 amperes meter.

Since PEA is well aware of accidents that might occur with leakage or short circuit current, we are implementing the grounding system to protect life and property.

What activities have been planned to promote these new rules and regulations?

We have produced brochures, posters and manuals to promote the awareness of grounding system installation for safety. We are also running an advertising campaign on television and in six different newspapers. Altogether, we are spending 3.5 million Baht on it. And we plan to continue promoting this new regulation for the next 1-2 years.

Who and how are you reaching out to promote the new regulation?

In the year 2004, we plan to promote and conduct a training programme for sub-contractors together with PEA’s offices in 73 provinces. We will also publish brochures, posters and manuals in order to further disseminate information to our users. The budget of this promotion will be 1.5 million Baht.

What are some of the challenges that PEA is facing in the implementation phase of this new grounding regulation?

We face two key challenges:

a] To assist designers, contractors and PEA’s officers to understand and apply the new standard of electric installation

b] To work with manufacturers and suppliers to produce and supply standardised equipment at reasonable prices

The publicity and promotional campaign has helped to generate awareness of the benefits of this new regulation and together with the industry we are confident of raising the level of electrical safety in the premises of our customers.

[lor]

All the attachments seemed to have gone from these posts! Can someone please explain in simple terms what an MEN system is, and how do I fit it.

Thanks

Chris

[Crossy]

All the attachments seemed to have gone from these posts! Can someone please explain in simple terms what an MEN system is, and how do I fit it.

Thanks

Chris

Yeah, after a while the attachment space fills up so some get deleted Have a look here http://www.crossy.co.uk/wiring/ and follow the link to "your distribution board".

WARNING Only install a MEN link if you have been informed that your local system is designed to use it. Although MEN is the required standard we are in Thailand, many remote areas still have not implemented and you could have a hazardous situation.

[elkangorito]

Hi Crossy.

Didn't whether to PM you about this or nut...decided on open forum.

I've been looking around the internet (primarily US sites), & I think I might have an idea as to why Thailands electrical system is such a mess. For example, we all know that here, the rebar in the concrete of a home is used as an earth (the main earth to be exact). This practice comes from an older version of the NEC regs. The 'new' 2005 version now outlaws this practice. Also, the current version NEC regs permits the use of some very controversial methods of earthing, such as using water pipes etc.

Australian regs have outlawed the use of such things for earthing for obvious reasons. What does IEEE say about this?

Also, many of the commentators, who claim to be electricians, seem to not even mentioning equipotential bonding. Apparently, the NEC states that anything that has the vaguest ability to conduct electricity can be used as part of an earthing system. Doesn't this sound like what happens here now? Did Thailand adopt these godawful ideas from the US electrical system?

I think if Thailand can get up to speed with its current (TT) electrical system, it'll be miles in front of the US system.

[Crossy]

IEE_16th_Edition_Wiring_Regulations_Illustrated_and_Explained.pdf

Hi Crossy.

Didn't whether to PM you about this or nut...decided on open forum.

I've been looking around the internet (primarily.................. .............................the US electrical system?

I think if Thailand can get up to speed with its current (TT) electrical system, it'll be miles in front of the US system.

Have a look at this document, it's quite old (2001) and doesn't dicuss the infamous 'Part-P' requirements, but it gives a pretty good idea what's considered good practice in the UK.

IEE_16th_Edition_Wiring_Regulations_Illustrated_and_Explained.pdf

The idea of equipotential bonding is to link all metal items together and thence to ground (not actually forming part of the grounding system), the idea being that all metal is at the same potential which (even if that potential is above true ground) reduces the possibility of a cross-body shock.

Here's some stuff on Part-P Partp_the_Building_Regulations_ExplainedNov04.pdf

[Tony Clifton]

Shocking pause.

Electrical scare yesterday.

Went to the local market , one vendor dropped the socket end of his 20 baht electrical cord in front of his table, raining, mud everywhere, I was looking at live chicks, , from the corner of my eye I saw my helpful pregnant wife had bent down to pick up the cord just as I shouted "Noooooo!" but too late she was already holding it.

Nothing happened but it gave me quite a jolt...

[Crossy]

Went to the local market , one vendor dropped the socket end of his 20 baht electrical cord in front of his table, raining, mud everywhere, I was looking at live chicks, , from the corner of my eye I saw my helpful pregnant wife had bent down to pick up the cord just as I shouted "Noooooo!" but too late she was already holding it.

Thank goodness there was no disaster :D

The problem is that many many times you can do just that and get away with it. This then leads to a cavalier attitude to any form of electrical safety, just in time to fry some unfortunate who just happens to be in the unlucky group.

I cringe every time I walk to our shops, the local council are forever puttting up and removing celebration lights, loads of fluorescent tubes (mainly in red, white and blue), taped joints, ballasts sitting in the mud, the only ground in sight is that which the poles are stuck into. The whole lot plumbed into the street lighting circuit which is doubtless protected by a massive fuse (nail), we see the occasional fizzing starter and everything goes off on occasion but nobody cares.

Amazingly nobody has died, yet!

[elkangorito]

IEE_16th_Edition_Wiring_Regulations_Illustrated_and_Explained.pdf

Hi Crossy.

Didn't whether to PM you about this or nut...decided on open forum.

I've been looking around the internet (primarily.................. .............................the US electrical system?

I think if Thailand can get up to speed with its current (TT) electrical system, it'll be miles in front of the US system.

Have a look at this document, it's quite old (2001) and doesn't dicuss the infamous 'Part-P' requirements, but it gives a pretty good idea what's considered good practice in the UK.

IEE_16th_Edition_Wiring_Regulations_Illustrated_and_Explained.pdf

The idea of equipotential bonding is to link all metal items together and thence to ground (not actually forming part of the grounding system), the idea being that all metal is at the same potential which (even if that potential is above true ground) reduces the possibility of a cross-body shock.

Here's some stuff on Part-P Partp_the_Building_Regulations_ExplainedNov04.pdf

Thanks Crossy but I couldn't download the large PDF...said something about being damaged.

Oz distinguishes between Protective Earthing systems & Equipotential Bonding & Oz regs say basically what you have said.

And about markets...if I go to a market, I always make sure I wear 'shoes', preferably leather with thick rubber type soles. All those 'speaker cable' extension cords scare the crap out of me. At my college, classrooms are full of this awful figure 8 cable. It invariably ends up tied in knots & being damaged by all of the 'metal legged' chairs that crush them. I'm dreading the day when the wafer thin insulation fails & I have to give CPR to an electrocuted student. I wish that they would use double insulated 'proper' cable for extension cords.

[elkangorito]

Does anybody know if "Danger" or "Lock out" safety tags are available in Thailand? If so, from where? Are they also available in English?

[goldfish]

I'm hoping you could clarify a couple of points for me as I have no electrical experience. The distribution board is, I believe, what you would call 'earthed to neutral'. It's the square D type. The earth bar (sits horizontal top centre) is connected to the neutral bar (sits vertically on the left) by a thin wire.

If I run an earth wire from an earth spike I intend to fit I simply connect it to the earth bar and disconnect the earthbar to neutral bar wire?

Living in a townhouse which shares it's side walls with other houses is not a problem when the other houses are not earthed?

Presumably I can replace one thai socket with a UK socket and use fused plugs?

[Crossy]

I'm hoping you could clarify a couple of points for me as I have no electrical experience. The distribution board is, I believe, what you would call 'earthed to neutral'. It's the square D type. The earth bar (sits horizontal top centre) is connected to the neutral bar (sits vertically on the left) by a thin wire.

If I run an earth wire from an earth spike I intend to fit I simply connect it to the earth bar and disconnect the earthbar to neutral bar wire?

Living in a townhouse which shares it's side walls with other houses is not a problem when the other houses are not earthed?

Presumably I can replace one thai socket with a UK socket and use fused plugs?

OK, there should be no issues using a UK outlet and fused plugs, but only one double per spur we have no ring mains here. Remember the BLACK wire is LIVE here, WHITE or GREY is NEUTRAL.

Provided the houses are electrically separate you should have no danger if the others are not grounded.

Your ground spike should go directly to the earth bar look here for grounding info. http://www.crossy.co.uk/wiring/protection.html

The earth-neutral (MEN or Multiple Earthed Neutral) link should be a FAT wire, at least as big as the incoming conductors. Do NOT remove it when you add your earth spike.

Check out http://www.crossy.co.uk/wiring/Consumer.html for the correct way to connect the MEN link, its location is particularly important when you have an ELCB / Safe-T-Cut device.

Lots more useful info. here http://www.crossy.co.uk/wiring/

[goldfish]

Thank you, Crossy. The link wire is normal size. I presume I can use a cut-off section of the earth wire as a link wire? Is there any way of turning off the electric coming into the fusebox, there seems to be no switch on the meter?

Will re-read your links before fitting the earth

[Crossy]

Thank you, Crossy. The link wire is normal size. I presume I can use a cut-off section of the earth wire as a link wire? Is there any way of turning off the electric coming into the fusebox, there seems to be no switch on the meter?

Will re-read your links before fitting the earth

There SHOULD be an incoming HRC fuse that you can remove to kill all the power, look by the meter.

Failing that just turn off the incoming breaker. None of your activities should touch hot wires but get yourself a neon screwdriver and wear rubber gloves and rubber shoes.

You say you're not a sparks, maybe it would be wise to get a local 'electrician' to do the actual hooking up under your direction.

[pete_r]

Another electrical question, if I may: I notice large sparks when I plug some electrical devices (in particular the laptop charger, and anything without a switch) into a socket, and would like to know what is the cause for them? In other countries they are much rarer/smaller or don't happen at all.

My two hypotheses are poor quality sockets or the absence of grounding in my house, but are there other explanations?

[elkangorito]

The likely cause is capacitors &/or inductors. That is, both of these things "charge up" when energised. This charging happens in a very short period of time & so, very high current is used for a very short period of time. The reason why you see sparks is because of the type of power outlets used here & also because humans are very slow compared to a switch.

This is why power outlets are switched in most other countries. Also, the power outlets in Thailand seem to be (by & large) inferior in quality.

[david96]

International Power Distribution

Unfortunately, in the absence of a common international power distribution system, it is important to understand that there are significant differences in the way power is distributed within many countries. Transmission systems mainly differ in the way the power source is earthed and how this earth is connected to the transmission system and the subsequent load.

The TN system and five of the most common variations.

The TN-C system has the neutral and earth functions combined in a single conductor throughout the system.

The TN-S system has separate neutral and earth conductors throughout the system.

The TN-C-S system has neutral and protective functions in a single conductor in part of the system. This is known as the MEN (Multiple Earth Neutral) system in Australia and New Zealand. The neutral is connected to earth at the main switchboard.

The TT system has exposed conductive parts of an installation connected to earth electrodes electrically independent of the electrodes of the source.

The IT system has no direct connection between live parts and earth, the exposed conductive parts of the installation are earthed. This system is used in operating theatres of hospitals in conjuction with Line Isolation Monitors (LIMs) as an example.

Note. The TT system is the one that is used by the majority of countries in the world and is the one used in Thailand. Some countries use both the TN-C-S and the TT systems.

[david96]

With a MEN system fault current does not return via the main earth but returns to the transformer though the neutral, the impedance must be low enough to trip a circuit breaker type C in less than 0.4 secs. ( Ref AS/NZ3000 )

If a RCD is used it must be protected by a protective device as an RCD does not have short circuit or overcurrent protection.

A combination RCD/MCB is known as a RCBO. An 30mA RCD must trip in less than 300ms.

Only one main earth is required per instalation connect to a 12.7mm copper clad electrode, main earth conductor 4sq mm stranded max 0.5 ohm (from the main switch board) to the electrode. (AS/NZ3000). Equipotential earth bonding min 4 sq mm.

So you may well ask what is the reason for a main earth?

In the event of the main incoming supply neutral conductor breaking or the polarity of the incoming supply being transposed all conductive metelwork and the earth electrode are at the same potential thus minimising the risk of a fatal electric shock. In this instance mild shocks may be received

In the above cases power must be disconnected until the fault is rectified.

Unless the supply authority can guarantee the integrity of their system (polarity) it might be advisable not to connect the MEN link until you get permission from the MEA or PEA in writing.

Your earthing system will be TT.

[Crossy]

The TT system is the one that is used by the majority of countries in the world and is the one used in Thailand. Some countries use both the TN-C-S and the TT systems.

Manly true in rural areas, however the Thai standards now call for a TN-C-S (MEN or PME) system, new buildings SHOULD be wired this way, so Thailand is one of the 'some' countries

TN-C-S is becoming more of a global standard in developed countries as it is very safe whilst keeping the amount of 'redundant' (not actually transmitting power) copper to a minimum.

Just to add to the fun, consider countries like the Philippines and several mainland European countries where there is no neutral provided to the home, both poles of the outlets are live (supply is phase-phase not phase-neutral).

[david96]

Is there a link to an English language translation of the Thai Industrial Standards ( TIS ) of their official wiring rules?

Where does it state in any official document that the MEN/TN-C-S/PME system is mandatory or is it an option in Thailand?

What are the requirements for earthing the supply authority neutral conductor on their LV 220/380 supply network?

All this might be rather difficult to find out.

[david96]

From the Thai Industrial Standards link

http://library.tisi.go.th/elib/cgi-bin/opa...p=&scid=zzz

see row 22 AS3006/1982 is mentioned along with standards from IEC,ISO,BS,DIN,NEC etc

It would appear that they do not write there own standards in most cases.

[Naam]

Just to add to the fun, consider countries like the Philippines and several mainland European countries where there is no neutral provided to the home, both poles of the outlets are live (supply is phase-phase not phase-neutral).

which european country Crossy?

[Crossy]

Just to add to the fun, consider countries like the Philippines and several mainland European countries where there is no neutral provided to the home, both poles of the outlets are live (supply is phase-phase not phase-neutral).

which european country Crossy?

555, if I could remember I would have said

I DO remember another member being confused by our continual reference to the neutral as his electrical training in his home country didn't use it. I THINK he was from Finland or one of the Scandinavian countries but I could be wrong

[Crossy]

All this might be rather difficult bl00dy impossible to find out.

I think Elkangorito found some useful stuff, but I can't find his posts refering to it

[david96]

All this might be rather difficult bl00dy impossible to find out.

I think Elkangorito found some useful stuff, but I can't find his posts refering to it

Try Norway --- I believe it is ( or was ) the only country to use the IT system with a protective device in both conductors.

[Crossy]

Try Norway --- I believe it is ( or was ) the only country to use the IT system with a protective device in both conductors.

Could well be, I also remember our place in Rome having double-pole MCBs (no they weren't ELCBs) although I never looked into the supply arrangements. I came across an IT system for the first time in the Philippines a couple of years back.

[david96]

And then there is the single phase 120/240 volt system 120v line to neutral 240v between the the two phases neutral is earthed. see also 240/480 50hz used on SWER systems in Australia. Neutral is earthed.

[Crossy]

And then there is the single phase 120/240 volt system 120v line to neutral 240v between the the two phases neutral is earthed. see also 240/480 50hz used on SWER systems in Australia. Neutral is earthed.

Shouldn't we really call these bi-phase systems as the two 120V lines are actually out of phase by 180^o (not 120^o as the IT lines are). Not that it really matters to the average chaps getting confused by all this And it's not related to Thai standards anyway.

[tjo o tjim]

I've been looking around the internet (primarily US sites), & I think I might have an idea as to why Thailands electrical system is such a mess. For example, we all know that here, the rebar in the concrete of a home is used as an earth (the main earth to be exact). This practice comes from an older version of the NEC regs. The 'new' 2005 version now outlaws this practice. Also, the current version NEC regs permits the use of some very controversial methods of earthing, such as using water pipes etc.

Australian regs have outlawed the use of such things for earthing for obvious reasons. What does IEEE say about this?

The change in the NEC was more to address electrical inspectors that suggested chipping away concrete in a column to expose re-bar for grounding step-down transformers. It was an idiotic practice both structurally and electrically, but in a concrete high-rise it is hard to establish a multipoint grounding system for a small transformer serving an individual floor of an office building.

Likewise, the water pipe is a stupid hold-over intended to *reduce* the risks in a bathroom, as well as to provide a good earth path into the ground. Because of corrosion and safety issues, most water meters have an isolating coupling now to protect workers outside from dangerous shocks. Equipotential bonding would be better in most cases for the water pipe, but it then becomes a mess when you make changes to an existing building to determine if your water pipe is a grounding electrode or just a bonded metal.

IEEE green book and gray book are both 1991 and are still pretty consistent with US codes. They encourage the concrete-encased (Ufer) ground, which is why re-bar in footings are often used as part of the grounding electrode system; the over all strategy is a multipoint ground electrode network, although it can still be tied into a single common-point ground (star topology with the main ground bus in the center).

Also, many of the commentators, who claim to be electricians, seem to not even mentioning equipotential bonding. Apparently, the NEC states that anything that has the vaguest ability to conduct electricity can be used as part of an earthing system. Doesn't this sound like what happens here now? Did Thailand adopt these godawful ideas from the US electrical system?

You have to remember that the difference between US and RoW is that the utilization voltage is 120V, with generally low fault currents at that level. At 480V, we often have well over 100kA available fault current, which should clear a breaker pretty fast. We also require GFP on 480V breakers over 800A, so any energized parts are likely to be cleared fairly quickly.

Equipotential bonding is better for many things, but it isn't a panacea. (Do you want to trip a breaker on the first fault or the second one?)

Like the idiotic specifications that require compliance with IEE, NEC, and IEC regulations ("where conflicts may arise, more stringent rules shall dictate"), Thailand has many hold-overs from different places and without a unifying theory of operation. Hopefully it will move more towards the European standards as the bulk of the theory of operation here is more consistent with those requirements than the US.

[david96]

Most residential / domestic electrical instalations the PSC would be low. Protective devices with of 3kA or 6kA on final subcircuits would comply.

Equipotential bonding is part of the earthing system. ( Ref AS/NZ3000 current edition.)

[Crossy]

It's not just Thailand, this is the newly "installed" kitchen fan in our office in Bangalore.

Heaven help us when they start installing the traction power (750V DC @ 10kA) on the metro.