Domestic Electrical Wiring

[electau]

All individual computer equipment exibit some leakage current generally this does not exceed 1.0ma. Your computer should be conected to a low impedance earth.

A UPS does not isolate your equipment. A 1:1 power isolating transformer which has no connection between the primary and secondary windings may be used but this is an expensive option. The protective earth (PE) is continuous to the 3 pin socket on the secondary side.

Earth your equipment and protect with an RCD.

You will always have this problem where 2 pin socket outlets are used.

The use of power boards with a 2 pin plug top and 3 pin outlets will give no protection. Power boards if found faulty should be taken out of service and the plug top and lead cut off.

PIn connection on a power board is in a clockwise direction. E, L, N. Likewise the polarity of socket outlets is the same. If you have reversed polarity on a socket outlet or plug top the polarity of the outlets on the power board will be reversed.

　

[InterestedObserver]

The statement "A UPS does not isolate your equipment" is incorrect.

Double-conversion / online

The online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. Although once previously reserved for very large installations of 10 kW or more, advances in technology have permitted it to now be available as a common consumer device, supplying 500 watts or less. The online UPS is generally more expensive but may be necessary when the power environment is "noisy" such as in industrial settings, for larger equipment loads like data centers, or when operation from an extended-run backup generator is necessary.

The above is from Wikipedia and clearly states that an online UPS provides electrical isolation and is available in sizes suitable for home computers.

Edited October 4, 2010 by InterestedObserver

[boatguy]

The statement "A UPS does not isolate your equipment" is incorrect.

Double-conversion / online

The online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. Although once previously reserved for very large installations of 10 kW or more, advances in technology have permitted it to now be available as a common consumer device, supplying 500 watts or less. The online UPS is generally more expensive but may be necessary when the power environment is "noisy" such as in industrial settings, for larger equipment loads like data centers, or when operation from an extended-run backup generator is necessary.

The above is from Wikipedia and clearly states that an online UPS provides electrical isolation and is available in sizes suitable for home computers.

So I wonder how you determine if a UPS is of the online type or not?

[Crossy]

So I wonder how you determine if a UPS is of the online type or not?

Rest assured, if it's an on-line UPS it will be spread all over the sales blurb, plus it will be significantly more expensive than the regular off-line beasties (although the price differential is getting smaller).

At 1800 Baht the GIZZ is unlikely to be an on-line unit.

[electau]

Most UPS units have a split mode power supply ( transformerless) and may exibit higher leakage currents.

The more expensive units for specalist applications have a transformer.

Leakage currents occur due the capacitors connected to earth.

However this type of transformer is not a 1:1 type as used for safety purposes where only one piece of electrical equipment is plugged in at any time.

With the wide use of RCDs this method of protection is now not often used. However IT systems using 1:1 transformers are found in some areas of hospitals etc, where disconnection from supply would be hazardous for patient safety and these systems have line isolation monitoring which alarm at a predetermined level.

　

[InterestedObserver]

Most offline / standby / Line-interactive UPS units run on bypass during normal operation; i.e. direct connection to the mains (line and neutral). The "split mode power supply" has nothing to do with the extent of isolation, or lack thereof, that a UPS provides.

[electau]

Most offline / standby / Line-interactive UPS units run on bypass during normal operation; i.e. direct connection to the mains (line and neutral). The "split mode power supply" has nothing to do with the extent of isolation, or lack thereof, that a UPS provides.

A UPS is not and should not be regarded as an isolation device between the existing supply and the equipment supplied for the purposes of safety.

They are two different pieces of electrical equipment and serve different purposes. A UPS is designed to supply power in the event of supply failure for a limited period until power is restored. An isolation transformer is just that , to isolate the supply from the load.

Only a 1:1 transformer with no connection on the secondary side to earth is regarded as an isolation transformer. The secondary side of the transformer is IT. They generally have a higher level of insulation between the primary and secondary windings.

I

[FarangBuddha]

I have just finished reading this entire thread [over 3 days] and taking notes! It was a great primer for someone like myself who has some basic knowledge of electrical installations but wanted to learn more on a basic safe electrical system install in a Thai home context. Thanks for all who contributed valuable input, especially Crossy and Elkangarito :jap: With this read, along with some choice You Tube videos, I now feel I have a much better understanding of the basics of a home electrical installation and the basic dos and don'ts when it comes to electricity in the home.

I have a smaoll home in Pattaya and wish to have it inspected for potential problems and to have some upgrades undertaken. The primary upgrade would be to install a new earthed wiring system [with MEN if used in Pattaya] using double insulated Romax cabling, along with re-wiring my system for separate circuits for lights, sockets/outlets, and direct lines to the air-cons and hot water heaters.

Can anyone here recommend a competent electrical contractor in Pattaya and is there anyone [preferably a farang] who is available to do a pre and post job inspection for me. (of course, I would be willing to pay for this).

Thanks in advance for any leads.

Edited October 11, 2010 by FarangBuddha

[doglover]

I have also just finished reading the entire thread and there is alot of great information and discussion. A BIG thank you to Elkangorito and Crossy as the main contributors :jap: plus the many other TV members who helped make this thread as valuable as it is. Also the Thailand Wiring page website is fantastic and many farang has surely been spared the runaround by local "electricians".

Seeing as I will be hovering around this thread I thought I would introduce myself....

I am a certified journeyman electrician from Canada. As an apprentice I worked about 6 months residential, 2 yrs commercial, 1yr oilfield construction and about 2 yrs industrial maintenance (where I learned hardly anything as it was change light bulb sort of maintenance). Now a journeyman for 10 years I have worked on and off at massive construction projects in the Canadian Oilsands. Sounds impressive but it's really not. I have been a "glorified labourer" since becoming a journeyman. With 500 - 1000 electricians on one project the work becomes "assembly line" production. At one point I installed mineral insulated heat trace on product piping for two years! I'm dam_n good at it though! But the trade-off to the good money I made was stagnant learning as an electrician. So I hope you'll exuse a stupid question or ten in the future from myself. If you don't open a code book or have to do any of your own engineering for 10 years it just slips from the brain, for myself anyways.

Ok. Onto my question of the day....

Throughout this thread there has been mention of insufficient power supply to some homes as the transformers capacity is being maxed out. This is case with my home (and the other two that just sprung up). It seems any similar case involving a farang the PEA wants us to foot the bill for Tx. I only have a single phase 15(45)Amp meter and that is all I need. Seeing as this is not an excessive request for power is it not the PEA's responsibility to provide another Tx in this scenario? The 3 phase 3 wire delta power lines run right on by the house already but the single phase is fed from the 3 phase Tx back in the village 0.7km away.

I hope Crossy and Elk are still around as sometimes I have noticed they don't get the appreciation they should. Also I am aware there are other knowledgeable electricians (and non-electricians) on TV. I look forward to any replies. Thank you.

[InterestedObserver]

Throughout this thread there has been mention of insufficient power supply to some homes as the transformers capacity is being maxed out. This is case with my home (and the other two that just sprung up). It seems any similar case involving a farang the PEA wants us to foot the bill for Tx. I only have a single phase 15(45)Amp meter and that is all I need. Seeing as this is not an excessive request for power is it not the PEA's responsibility to provide another Tx in this scenario? The 3 phase 3 wire delta power lines run right on by the house already but the single phase is fed from the 3 phase Tx back in the village 0.7km away.

People need to distinguish between insufficient transformer capacity and excessive voltage drop caused by undersized secondary wires. Even a maxed out transformer will still provide an acceptable voltage drop, it's the long undersized secondary cables that cause the low voltage at your house.The transformer taps are usually set to provide nominal voltage under load at the transformer.

Edited March 3, 2011 by InterestedObserver

[doglover]

People need to distinguish between insufficient transformer capacity and excessive voltage drop caused by undersized secondary wires. Even a maxed out transformer will still provide an acceptable voltage drop, it's the long undersized secondary cables that cause the low voltage at your house.The transformer taps are usually set to provide nominal voltage under load at the transformer.

Good point IO. But I don't have low voltage at the house. I have 230V.

[Crossy]

People need to distinguish between insufficient transformer capacity and excessive voltage drop caused by undersized secondary wires. Even a maxed out transformer will still provide an acceptable voltage drop, it's the long undersized secondary cables that cause the low voltage at your house.The transformer taps are usually set to provide nominal voltage under load at the transformer.

Good point IO. But I don't have low voltage at the house. I have 230V.

The acid test is under load. What does it fall to when you pull your allotted 45A ?

On the end of 700m of 16mm it could get quite interesting (even PEA wouldn't install like that, would they?), any idea what size your incoming cable to the meter is (should be marked).

[doglover]

People need to distinguish between insufficient transformer capacity and excessive voltage drop caused by undersized secondary wires. Even a maxed out transformer will still provide an acceptable voltage drop, it's the long undersized secondary cables that cause the low voltage at your house.The transformer taps are usually set to provide nominal voltage under load at the transformer.

Good point IO. But I don't have low voltage at the house. I have 230V.

The acid test is under load. What does it fall to when you pull your allotted 45A ?

On the end of 700m of 16mm it could get quite interesting (even PEA wouldn't install like that, would they?), any idea what size your incoming cable to the meter is (should be marked).

See, shows you what I know.. Ok, at basically no load it is actually 225V. And with almost full house load (sorry no amprobe handy for a 45A reading) it nose dives to 160V. Now I believe I may have gone over the 45A limit of the meter so I will do a load calc later on and try to get the load at 45A, give or take a few.

But here's the thing. Even when laying in bed for sleep with the house 'shutdown' for the night and only running a basic upright fan and exterior lights (plus possibly the fridge) I can still here the fan working at different voltages. This is where I came to my "PEA Tx is maxed out" conclusion. I also understand that 700M is a hell of a long way and I will provide cable sizes tomorrow if I can see them. On a quick inspection I could only see the metre markings and no size info on the drop. But the single phase wires on the pole are aluminum and look bigger than 16mm2, I don't say that with confidence though as it is up there a little bit and my brain thinks in AWG sizes. So is my logic failed? Why do my fans keep changing rpm under very light (and heavy) house load?

P.S. It just came to me that at 10:30pm I should not be competing with anyone for available power as I live just outside a village in Issan and everyone is asleep already (and it is the odd rice farmer that will be running air conditioning!). So is my voltage drop so nasty that the fridge/freezer kicking in and out is varying my fans rpm?

[InterestedObserver]

P.S. It just came to me that at 10:30pm I should not be competing with anyone for available power as I live just outside a village in Issan and everyone is asleep already (and it is the odd rice farmer that will be running air conditioning!). So is my voltage drop so nasty that the fridge/freezer kicking in and out is varying my fans rpm?

Yup, your voltage regulation is terrible. Anytime anything kicks "on" on your single-phase line the fan speed changes.

[powderpuff]

You have to contact the PEA to arrange to get another transformer installed (free to you). Since they are a monopoly they have to meet the demand.

[doglover]

People need to distinguish between insufficient transformer capacity and excessive voltage drop caused by undersized secondary wires. Even a maxed out transformer will still provide an acceptable voltage drop, it's the long undersized secondary cables that cause the low voltage at your house.The transformer taps are usually set to provide nominal voltage under load at the transformer.

....ahem....Good point IO...

On the end of 700m of 16mm it could get quite interesting (even PEA wouldn't install like that, would they?), any idea what size your incoming cable to the meter is (should be marked).

I have some info with more substance for you Crossy. The run of cable from the 3 phase Tx to my house is actually a whopping 830M and then carries on for a total distance of over 1100M. I am the last house on the road from the village but at the end of the line some farmers have ran there leads for minor loads another 200M supported with bamboo poles and such. Still hard to tell the size of the single phase feed from pole to pole but it does appear to be in the 16mm2 (alu) range but I cannot verify. The cable drop to the meter is only 10mm2. I cannot verify that it is alu but I would assume it be but then I have an undersized drop. My house is fed with 45M of 10mm2 (cu) to a 63A RCBO. This seems like it would be near the edge as far as sizing in respect to voltage drop. I was not here during the electrical phase of house construction (unfortunately). Will need a new feed regardless in the future when I add some more load.

A little history on the PEA install. The last house out of the village used to be about 400M from the Tx with only 5 drops to 5(15)A metres (plus another leg that taps off from the single phase back in the village of unknown load). The way I see it they made this 1100M run thinking it would only be the odd farmer needing a little power for a couple lights or a small pump as it was all farmland. Since then the villages raw land has been eaten up and houses are springing up on roads leading out of the village. Just in the last few years a few shacks 5(15)A and a few houses 15(45)A have sprung up with mine as the last home.

So it is time for some changes.....as I only have a small air con unit at the moment and 10kW of hot water heaters. In the next few years I plan on adding 4 or 5 more aircon units plus another 8kW water heater. I realize I will have to upgrade the incomers and my meter at that time. Seeing as there is massive voltage drop with my modest request for power does it not fall on PEA to provide another Tx?

*Refering to my last post the only other house out here with an aircon unit is my neighbour who runs it every night this time of year. So under light house load on my end I think this is the culprit (along with other fridges/freezers) at night that is varying the voltage to my fan (still cool enough for me) at bedtime.

Pictures:

1) my single phase is the one at top left

2) 3 phase Tx of course

3) the pole my meter is on in front of my house

4) my meter wires (popped off the lug cover but do not have an insulated flat blade (no disconnect) and the termination was done quite well so I cannot see if the drop is alu or cu)

[powderpuff]

Yep the PEA will need to come out & do a survey.

One reading of 160 volts should end the discussion.

[InterestedObserver]

Doglover,

From your anticipated future load you should start thinking 3-phase. You will be hard pressed with a 1-phase supply to meet your stated requirements unless the transformer is located closed to your house..

Edited March 4, 2011 by InterestedObserver

[powderpuff]

I am running a similar load on single phase 30/100. But in the Big Mango.

[Crossy]

I would agree with the above sentiments on 3-phase, whilst it shouldn't really be necessary with that anticipated load your rural location is not conducive to a 'proper' supply, plan for 3-phase. Incidentally, we're not advocating having any 3-phase equipment, just installing what is effectively three single-phase supplies each of which carries about 30% of your load.

You definitely need a local transformer and you're lucky in that the 25kV goes past your door. PEA 'should' supply free of charge so they ought to be your first port of call.

Alternatively talk to a local contractor about supplying your own Tx (at your cost), this would make you independent of PEA nailing other supplies onto 'your' Tx.

Whilst PEA are supposed to meet the required demand they have limited manpower and budget and it may be more effective to provide your own personal Tx which could then likely be single-phase

[doglover]

Yep the PEA will need to come out & do a survey.

One reading of 160 volts should end the discussion.

This is the way I see it. And there cannot be any reason why I should have to put out even 1 baht for it. Thanks.

[Crossy]

Yep the PEA will need to come out & do a survey.

One reading of 160 volts should end the discussion.

This is the way I see it. And there cannot be any reason why I should have to put out even 1 baht for it. Thanks.

Agreed of course, but the practical approach (i.e. to get it done in your lifetime) could be to bite the financial bullet Depends upon how long you (and any electrical kit) are prepared to put up with 160V.

[doglover]

I would agree with the above sentiments on 3-phase, whilst it shouldn't really be necessary with that anticipated load your rural location is not conducive to a 'proper' supply, plan for 3-phase. Incidentally, we're not advocating having any 3-phase equipment, just installing what is effectively three single-phase supplies each of which carries about 30% of your load.

Thanks for the comments IO, PP and Crossy. The 3 phase or single phase for this approx. load debate came up earlier in this thread. And I understand 3 phase would be the ideal and understand completely what you are saying. The thing is my house is already wired for single phase and without re-wiring I would not have the ideal setup of zoning the phases to seperate areas. And if I had your money Crossy I would just go ahead and install the 3 phase and rectify any indescrepencies . Have a couple questions though while we're on 3 phase....

- From school I remember that for every 3 phases only 1 neutral is required to return any imbalance of the phases so long as it is always A,B,C and not A,A,C for example. However, a neutral can be run with each individual phase if desired. I recently saw a 3 phase install in a condo unit in LOS where the latter was the case (although I didn't actually take a count). What would be the 'norm' for AUS 3 phase residential installs?

-Also, this condo was in the Rayong area (not the city itself) and from what I gather by following your posts Crossy is that the MEN system should be in place in that area. If the PEA confirms it to be in place I gather the MEN link would be installed at the line side of the main breaker for the entire complex only and not in each condo units CU. Is this correct?

You definitely need a local transformer and you're lucky in that the 25kV goes past your door. PEA 'should' supply free of charge so they ought to be your first port of call.

I am lucky, and the free of charge is what I have been looking for.

Alternatively talk to a local contractor about supplying your own Tx (at your cost), this would make you independent of PEA nailing other supplies onto 'your' Tx.

Would be oh so sweet!

Whilst PEA are supposed to meet the required demand they have limited manpower and budget and it may be more effective to provide your own personal Tx which could then likely be single-phase

My wife phoned them this morning and the information I gave has been passed on to the appropriate persons, they claim. So now I'll just give them some Thai time and see what happens.....

(Any educated guesses as to what an appropriately rated single phase transformer would cost if I had Crossy's money? )

Thanks all!

EDIT - forgot to add others responses in quotes

EDIT 2 - I realize I could be waiting longer than I want to get my free Tx. Point taken about the advantage of footing the bill on my own

Edited March 4, 2011 by doglover

[electau]

You need to calculate your max demand first.

The PEA would have to extend their HV supply to near your property and install a transformer.

This will solve your voltage drop problems. You would most probably have to supply the capital costs involved, it would mean that the lines and transformer woud be owned by the PEA and maintained by them.

It would be up to the PEA whether they would supply 1 or 3 phase supply depending on load.

[doglover]

You need to calculate your max demand first.

The PEA would have to extend their HV supply to near your property and install a transformer.

This will solve your voltage drop problems. You would most probably have to supply the capital costs involved, it would mean that the lines and transformer woud be owned by the PEA and maintained by them.

It would be up to the PEA whether they would supply 1 or 3 phase supply depending on load.

From your response I will assume you have only read one or two paragraphs from one of the most recent posts. But I do, nevertheless, appreciate your response.

[doglover]

After having another look at your post, I see what you're getting at Electau. I revoke my smart ass comment. Especially after reading other posts from yourself regarding electrical. I hope you contribute answers to more of my stupid questions in the future .

[doglover]

Geez. And I thought I rambled on forever. Check out this thread...http://www.thaivisa.com/forum/topic/221254-serious-electricity-supply-problem-advicedirection-urgently-needed-please/ if you are having any issues with insufficient power supply. Alot of real good advice how to rectify and some even some prices mentioned.

[dragons70]

G'day gents,

I have read a bit of the information here and its clear to me that there are some very knowledgable fellas when it

comes to safe electricity in Thailand. I am currently building a house and will hire the electrician soon. If you were going to

provide a list to a Thai electrician of equipment and requirements that you would want for the safest electrical system possible (within reasonable

budget), what would your list be?

Thanks in advance,

D

[Crossy]

As a minimum he will need in addition to the regular tools (screwdrivers etc.):-

1. A multimeter with a decent low Ohms range (< 20 Ohms full scale).
   
2. An insulation tester (250V and 500V DC test ranges).
   
3. An earth resistance tester or an earth loop impedance tester.
   
4. An RCD tester would be nice.
   
5. An outlet polarity tester is handy as a quick test.
   

1-3 are non-negotiable if a safe installation is required.

The above are all catered for if he has an Installation Tester (expensive).

Of course, all the gear in the world is of no use if he does not know how to use it, how to interpret the results and how to fix the issues it brings to light.

Good luck!

[dragons70]

As a minimum he will need in addition to the regular tools (screwdrivers etc.):-

1. A multimeter with a decent low Ohms range (< 20 Ohms full scale).
2. An insulation tester (250V and 500V DC test ranges).
3. An earth resistance tester or an earth loop impedance tester.
4. An RCD tester would be nice.
5. An outlet polarity tester is handy as a quick test.

1-3 are non-negotiable if a safe installation is required.

The above are all catered for if he has an Installation Tester (expensive).

Of course, all the gear in the world is of no use if he does not know how to use it, how to interpret the results and how to fix the issues it brings to light.

Good luck!

Thanks for taking the time to reply Crossy,your info here is great. I was probably unclear with my post asking to list "equipment" required for a safe electrical plan.

I am more after - what type/brand of circuit breaker should I use, what size meter required for small house with minimal appliances (1 air con unit, 1 washing machine, gas cooking)

How many circuits should I do - 1 for hot water,washine machine etc, 1 for kitchen, 1 for lights in each room? (only have 2 rooms of 9m x 3;5m), if the breaker box is earthed, is it still necessary to use

a grounding pole? Which is best way to protect computer and hifi equipment from lightning and power surges?

Cheers mate, your efforts are much appreciated as my sparky does not speak a word of English and my Thai is very limited