Domestic Electrical Wiring

[Crossy]

Not been much activity on this thread for a while so it deserves a bump.

A mate sent me this today, got to be shared, and it demonstrates that it's not just Thais with little respect for electricity, I think they are (were?) countrymen of yours Elkangorito

Homemade flotation device - 3.00 Aus$

Hosting the death BBQ in your pool - priceless.

I especially like the floating pontoon flip flops (Thongs in Aussieland) and the splash proof outside RED extension lead held up by a door stopper.

[Lite Beer]

Even My Thai Wife saw the problems.

Unbelievable.

[Crossy]

The original email with this photo has certainly pushed some buttons with the Aussies on the circulation list

Evidence that it's NOT Australia:-

Nice try but I am afraid this is definitely NOT an Australian image.

Judging by the drab paving and garden including the hideous blue door frames on the building next door, the fact that there is not one recognisable Australian beer on the table, that no Australian would ever have an electric powered bbq, that no Australian would ever purchase, or wear for that matter, a pair of thongs (flip flop to you poms) like that, that no Australian would ever have a pool like that in his garden and finally that the pasty white skin of the two individuals prove that they are not Australian, this is definitely ENGLAND.

Press my button this morning? Certainly did!

Not UK plugs.

Not obese enough to be English.

Maybe Scottish judging from the bluish white skin

Put it down to drunks sans frontiers.

When pressing buttons, remember to stand on rubber.

I reckon, judging by the pasty look and wide variey of beer, thay they're BELGIAN.

[Frotting]

I think we should recommend the 'belt and braces' system.

ELCB, local ground spike AND an MEN link (subject to the multiple earthed neutral caveat).

Can't believe we could get much safer.

Just one thing about the ground spikes I've seen (and used) that are available in Thailand.

In the UK they are made of Copper. In Thailand they 'look like copper' but on close inspection can be seen to be steel rods (just test the weight) that have been copper plated.

Now when banging these into the ground, imagine the scenario: The thin (10 microns?) copper plating is scoured off. Over time, water penetrating the ground corrodes the (now) steel rod. Iron oxide forms on the outside (which is an insulator) and your ground spike is no longer an efficient conductor to earth.

Does anybody know where to get REAL copper ground spikes in Thiland, or should we bring a few back on our next visit to Europe?

It may seem like only a small point, but I believe it a valid one. A noble metal of high conductivity should be the preferred way. I suppose we could always use silver if copper is not available

[Crossy]

If you hunt out the decent steel/copper rods they actually have quite a thick copper layer, I don't think it's just plated on. The steel core helps you bash it into the rock hard earth.

Solid copper are available, I've seen them in HomePro, obviously they cost much more, they also have a nasty habit of bending under the influence of a Farang equipped with a lump hammer

[Khonwan]

As described in other posts, I have a very long (1,556m) 3-phase supply. The concrete pole supporting my 50kVA transformer also supports my kWh-meter. The high voltage lines are protected with an overhead ground-wire. Unfortunately, the overhead ground wire terminates at this pole (due to lack of budget, PEA did not extend the long overhead ground to the transmission poles beyond my location). The transformer is grounded at this pole. So too is the meter. Both earth-ground rods are therefore only inches apart. At the other end of the system, my house is electrically earth-grounded.

My kWh-meter exploded again last week during a thunder storm. This is the third time in less than one year...the second time in less than two months (always due to lightning strikes).

The local PEA manager now wants me to earth my neutral cable every 500m. He also wants me to install phase-to-neutral surge protectors across the cables just after the meter and again just before entry to the house (rated at 2.5kA 500V).

I'm concerned that this remedy may not help. I think the real cause is the location of the grounded kWh-meter on the same lightning-grounded transformer pole. I think the kWh-meter should be re-located to the next pole (my low voltage pole) and earth-grounded.

I'd appreciate comments from the sparkies before Tuesday since the local PEA manager is to visit me then.

Thanks

Khonwan

Update:

My local PEA manager (a new and much better manager) came out around 7 days ago and improved the earths around my transformer / meter pole. He removed the transformer ground that was connected to the high voltage lightning ground and ran it direct to ground. The meter ground had already been moved to the other side of the pole at a distance of perhaps 30cm to the lightning ground rather than the previous 3cm after my meter exploded a fourth time last year. He installed a 2m radius ground-ring with all three grounds attached. He also installed another ground at my next pole plus installed in-line MOV’s on my side of the meter and on the last PEA high voltage pole adjacent to my property.

I was pleased, though suggested I still thought that removal of the meter to the next pole would have been even better.

We had a heavy electrical storm two days ago. My meter exploded for the fifth time! PEA came out again yesterday and this time did remove the meter to two poles further along (closer to me). They then grounded the neutral at each of the next 3 poles (40m apart).

I now hope and trust that there will be no sixth time.

I’m also now thinking of removing my 50mm cables from Phase B and Phase C at the transformer and combining them with Phase A to provide me with an equivalent 150mm single-phase supply with a 50mm neutral that will be grounded every 200m. This will allow me to use individual single-phase appliances in excess of 3kW (to a maximum of 9kW). My present long line only permits 3kW per phase before suffering voltage drop to 210V (from a non-load 235V).

Rgds

Khonwan

[elkangorito]

I hate to be the one who "told you so" but I did "tell you so" here;

http://www.thaivisa.com/forum/index.php?s=...t&p=1621065

By paralleling your 3 phases (cables), you will gain nothing. Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy"). I've also spent the time to re-do the calculation based upon your new requirements & the result is the same. If you wish the problem to be solved, you will need to upgrade your cables to 300 square millimetres per phase (aluminium, for a 3 phase installation). The size of the cable can be reduced by using copper cable but this will cost more & will require a recalculation.

Please, do not trust "web cable calculators" because they may not take into account;

1] cable insulation type.

2] cable insulation temperature rise.

3] arrangement of cables (aerials, buried direct, enclosed in thermal insulation, unenclosed in air etc etc).

4] location ambient soil/air temperatures.

5] grouping & parallel arangements of cables (trefoil etc).

6] type of Over Current device (the speed at which a circuit breaker operates, which is important over long cable distances).

At the end of the day, you are faced with no other option but to increase cable size (to 300 mm squared Aluminium per phase) if you wish to escape voltage drop problem.

[Khonwan]

I hate to be the one who "told you so" but I did "tell you so" here;

http://www.thaivisa.com/forum/index.php?s=...t&p=1621065

By paralleling your 3 phases (cables), you will gain nothing. Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy"). I've also spent the time to re-do the calculation based upon your new requirements & the result is the same. If you wish the problem to be solved, you will need to upgrade your cables to 300 square millimetres per phase (aluminium, for a 3 phase installation). The size of the cable can be reduced by using copper cable but this will cost more & will require a recalculation.

Please, do not trust "web cable calculators" because they may not take into account;

1] cable insulation type.

2] cable insulation temperature rise.

3] arrangement of cables (aerials, buried direct, enclosed in thermal insulation, unenclosed in air etc etc).

4] location ambient soil/air temperatures.

5] grouping & parallel arangements of cables (trefoil etc).

6] type of Over Current device (the speed at which a circuit breaker operates, which is important over long cable distances).

At the end of the day, you are faced with no other option but to increase cable size (to 300 mm squared Aluminium per phase) if you wish to escape voltage drop problem.

You are treating this as if I ignored your advice. The fact is, as should be plain to see from my previous posts, my installation was completed before I even joined Thaivisa.

You say I will gain nothing by paralelling my cables: you are incorrect. I could, for example, use a welding unit (consuming 20A) or a 7kW shower heater. At present, I am limited to a total 3kW per phase so cannot use either of these examples. That...is the point. Furthermore, I would not need to try to balance loads between the phases - what a blessing that would be.

You are treating this as if I ignored your advice. The fact is, as should be plain to see from my previous posts, my installation was completed before I even joined Thaivisa.

“Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy").” Re-read my post and you should recognize that I obviously understand this.

You say I will gain nothing by paralleling my cables: you are incorrect. I could, for example, use a welding unit (consuming 20A) or a 7kW shower heater. At present, I am limited to a total 3kW per phase so cannot use either of these appliances. That...is the point. Furthermore, I would not need to try to balance loads between the phases - what an obvious benefit that would be.

You assume I have used "web cable calculators". This is not the case. I have already posted my own simple arithmetical equation (that incorporates assumptions reflecting my actual environmental conditions), which was used in my calculations. Post installation tests by me (witnessed by astounded PEA managers) have confirmed the accuracy of my equation.

You state my supply is 380V. I never did - my supply is actually 415V. You indicate a required current of 32A per phase - where did this figure come from? A more correct figure would be 75A (25A per phase).

You state I need 300mm² per phase. This is way over the top. Both my equation and PEA agree that I should have had 95mm² per phase. Even applying common sense, if 50mm² x3 is providing 9kW within the 5% voltage variance rule, 95mm² x3 is obviously going to provide just less than twice 9kW, i.e. it would provide my targeted 17kW.

You must consider the info already presented by me (rather than assumed by you) and realise that a voltage drop of 13% of 240V results in approximately 209V, which represents a 5% drop against appliances rated at 220V and is therefore totally acceptable.

My options are many but, since I can use welding units and most other farm equipment at the location of my transformer (all my [wife’s] land) with no voltage drop issues, I am not forced to spend hundreds of thousands of baht to improve my situation.

Rgds

Khonwan

[lopburi3]

I don't know about elkangroito but I was thinking this was the other electric thread in my post above so has nothing to do with this thread and will remove it.

[Khonwan]

^^ Cut & Paste error. Please ignore my repetitive 1st & 2nd paragraphs in my previous post.

Khonwan

[elkangorito]

My comments in blue.

I hate to be the one who "told you so" but I did "tell you so" here;

http://www.thaivisa.com/forum/index.php?s=...t&p=1621065

By paralleling your 3 phases (cables), you will gain nothing. Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy"). I've also spent the time to re-do the calculation based upon your new requirements & the result is the same. If you wish the problem to be solved, you will need to upgrade your cables to 300 square millimetres per phase (aluminium, for a 3 phase installation). The size of the cable can be reduced by using copper cable but this will cost more & will require a recalculation.

Please, do not trust "web cable calculators" because they may not take into account;

1] cable insulation type.

2] cable insulation temperature rise.

3] arrangement of cables (aerials, buried direct, enclosed in thermal insulation, unenclosed in air etc etc).

4] location ambient soil/air temperatures.

5] grouping & parallel arangements of cables (trefoil etc).

6] type of Over Current device (the speed at which a circuit breaker operates, which is important over long cable distances).

At the end of the day, you are faced with no other option but to increase cable size (to 300 mm squared Aluminium per phase) if you wish to escape voltage drop problem.

You are treating this as if I ignored your advice. The fact is, as should be plain to see from my previous posts, my installation was completed before I even joined Thaivisa.

I do apologise. You are correct. I should've read the complete history first.

You say I will gain nothing by paralelling my cables: you are incorrect. I could, for example, use a welding unit (consuming 20A) or a 7kW shower heater. At present, I am limited to a total 3kW per phase so cannot use either of these examples. That...is the point. Furthermore, I would not need to try to balance loads between the phases - what a blessing that would be.

Your initial post says otherwise. It mentions "I've tested "known" loads (single-ph appliances) up to 5 kW and the resulting voltage readings seem to bear it out."

This information is no longer the same as originally posted by yourself. It appears that a 7kW water heater & a welding unit have been added to your Demand since your original post. Not only this but you have lowered your acceptable kW usage from 5.6kW to 3kW. Generally, if I do a Maximum Demand calculation, I allow a minimum 20% (usually 25%) "future" allowance for any increases. A proper "Discrimination Demand" calculation would have negated this problem. I'm sorry to "shut the gate after the horse has bolted." This calculation can only be done using Standards (which may not have been available to you but are available to non-Thai qualified electricians.) Whether the Standards are NEC or IEC, the Demand Calculation results are pretty much the same. This calculation can be done by adding up currents but this will end up being very expensive with regard to cable cost.

http://www.thaivisa.com/forum/index.php?s=...t&p=1155352

"Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy")." Re-read my post and you should recognize that I obviously understand this.

Granted.

You assume I have used "web cable calculators". This is not the case. I have already posted my own simple arithmetical equation (that incorporates assumptions reflecting my actual environmental conditions), which was used in my calculations. Post installation tests by me (witnessed by astounded PEA managers) have confirmed the accuracy of my equation.

Actually, I did not assume that you ONLY used these dreadful "web cable calculators". I mentioned this for the benefit of all concerned. To all...DO NOT USE THEM!!!

You state my supply is 380V. I never did - my supply is actually 415V. You indicate a required current of 32A per phase - where did this figure come from? A more correct figure would be 75A (25A per phase).

Unless I am mistaken, I don't see anywhere that you mentioned 415 volts.

The reason why I assumed 380 volts (3 phase) was because you mentioned 230 volts (single phase.) To an electrical person, this means 220 volts. Why? Quite simply, if you were supplied with 415 volts 3 phase, your MINIMUM single phase voltage would be 240 volts. It is quite common for energy suppliers to provide a higher than usual voltage (but still within acceptable limits) if the transformer leg/branch is lightly loaded. For example, it is quite common in Australia to have a single phase voltage of 250-260 volts due to a light transformer load. Australia does not supply 220 volts. It supplies 240 volts, although it should be 230 volts (IEC). To further back-up my assumptions, Thailand mostly uses a 380 volt 3 phase supply (220 volts single phase).

With regard to current, this is very simple. I simply did the following, as I would do with any new installation;

Wattage figures (approximate) supplied by you.

5 600 Watts divided by 220 = about 25.5 Amps.

(Future allowance) 25% of 25.5 Amps = about 6.4 Amps.

25.5 + 6.4 = 31.9 or close enough to 32 Amps.

Most sensible electricians would allow for this.

BTW, 5.6 kW plus 20% = 7kW (this is your present max load per phase, is it not?)

You state I need 300mm² per phase. This is way over the top. Both my equation and PEA agree that I should have had 95mm² per phase. Even applying common sense, if 50mm² x3 is providing 9kW within the 5% voltage variance rule, 95mm² x3 is obviously going to provide just less than twice 9kW, i.e. it would provide my targeted 17kW.

To fall within the universally accepted "no more than 5% voltage drop" rule, your above results are flawed.

At one stage, the PEA recommended that you use 700mm squared cable (Aluminium aerials, I assume PVC insulated). This is not far from the truth. BTW, I still stand by my calculation of 300mm squared Aluminium PVC insulated aerial cables to provide a no greater than 5% voltage drop under a maximum load of 32 Amps per phase. 1.5km is a VERY VERY long way to run low voltage cables. Normally, this is considered uneconomical. A higher voltage would normally be used (11kV) to within an "economical" distance from the lower voltage load.

You must consider the info already presented by me (rather than assumed by you) and realise that a voltage drop of 13% of 240V results in approximately 209V, which represents a 5% drop against appliances rated at 220V and is therefore totally acceptable.

Unfortunately, I had alreadly assumed a supply voltage of 380 volts per phase, for obvious reasons as stated in the above posts.

My options are many but, since I can use welding units and most other farm equipment at the location of my transformer (all my [wife's] land) with no voltage drop issues, I am not forced to spend hundreds of thousands of baht to improve my situation.

Rgds

Khonwan

Australian Standards say that the neutral conductor minimum size shall be sized to that of the total current to be carried, where there is more than one active conductor. In other words, if the sum of your Active conductors provide a total of 45 Amps current, the neutral conductor must be sized the same (45 Amps). This means that the neutral conductor will be bigger than any of the paralleled conductors. The reason is that an "earth return circuit" (MEN or otherwise) is not considered a "normal" current carrying conductor. Its' sole purpose is to provide a "reduced impedance path" so that Protective Devices (circuit breakers) can operate quicker under fault conditions (within 0.4 seconds at rated voltage). In your situation, a 50mm squared neutral used with 3 x paralleled 50mm squared Active conductors is unacceptable (potentially dangerous, even though the neutral is/will be/could be earthed every 500m). An appropriately sized "hard" neutral is required to maintain system integrity.

"Fault Current" is a MAJOR consideration when sizing cables over long distance. The type of insulation, the method of cable installation, the type (Class) of Protective Devices used, all influence this. This also formed part of my previous calculation. I wonder, did any of your/Thai calculations include this?

With regard to Aluminium conductors, connections to, and joints in, aluminium conductors must be made using components specifically designed for the connection of aluminium conductors and techniques specified by the manufacturer. When connecting aluminium conductors, the following special factors associated with aluminium should be considered:

[a] Removal of the aluminium oxide film from the conductors.

The relative softness of aluminium.

[c] The different coefficient of linear expansion of aluminium and other metals.

[d] Avoiding contact with dissimilar metals that may initiate galvanic action.

Khonwan, I'm sorry if I seemed to "take the piss" out of you. I have only ever tried to help people here but since the influx of many "experts", I've decided that my advice is no longer "freely" available. This is not to say that I require money.

Edited April 4, 2008 by elkangorito

[Khonwan]

Hi elkangorito,

Please find my response in red.

Kind regards

Khonwan

My comments in blue.

I hate to be the one who "told you so" but I did "tell you so" here;

http://www.thaivisa.com/forum/index.php?s=...t&p=1621065

By paralleling your 3 phases (cables), you will gain nothing. Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy"). I've also spent the time to re-do the calculation based upon your new requirements & the result is the same. If you wish the problem to be solved, you will need to upgrade your cables to 300 square millimetres per phase (aluminium, for a 3 phase installation). The size of the cable can be reduced by using copper cable but this will cost more & will require a recalculation.

Please, do not trust "web cable calculators" because they may not take into account;

1] cable insulation type.

2] cable insulation temperature rise.

3] arrangement of cables (aerials, buried direct, enclosed in thermal insulation, unenclosed in air etc etc).

4] location ambient soil/air temperatures.

5] grouping & parallel arangements of cables (trefoil etc).

6] type of Over Current device (the speed at which a circuit breaker operates, which is important over long cable distances).

At the end of the day, you are faced with no other option but to increase cable size (to 300 mm squared Aluminium per phase) if you wish to escape voltage drop problem.

You are treating this as if I ignored your advice. The fact is, as should be plain to see from my previous posts, my installation was completed before I even joined Thaivisa.

I do apologise. You are correct. I should've read the complete history first. Thank you.

You say I will gain nothing by paralelling my cables: you are incorrect. I could, for example, use a welding unit (consuming 20A) or a 7kW shower heater. At present, I am limited to a total 3kW per phase so cannot use either of these examples. That...is the point. Furthermore, I would not need to try to balance loads between the phases - what a blessing that would be.

Your initial post says otherwise. It mentions "I've tested "known" loads (single-ph appliances) up to 5 kW and the resulting voltage readings seem to bear it out."

This information is no longer the same as originally posted by yourself. It appears that a 7kW water heater & a welding unit have been added to your Demand since your original post. I have never provided a breakdown of my requirements other than to say I required a maximum 17kW. Not only this but you have lowered your acceptable kW usage from 5.6kW to 3kW. Again, you are not interpreting my posts properly: 5.6kW x3 = 17kW; 3kW = the amount of power currently available to me per phase. I have therefore not lowered my expectations. Generally, if I do a Maximum Demand calculation, I allow a minimum 20% (usually 25%) "future" allowance for any increases. A proper "Discrimination Demand" calculation would have negated this problem. I'm sorry to "shut the gate after the horse has bolted." This calculation can only be done using Standards (which may not have been available to you but are available to non-Thai qualified electricians.) Whether the Standards are NEC or IEC, the Demand Calculation results are pretty much the same. This calculation can be done by adding up currents but this will end up being very expensive with regard to cable cost.

http://www.thaivisa.com/forum/index.php?s=...t&p=1155352

"Quite simply, the load will increase such that the single phase cables will suffer the same voltage drop as did the 3 phases under a reduced load (the "law of conservation of energy")." Re-read my post and you should recognize that I obviously understand this.

Granted. Thank you.

You assume I have used "web cable calculators". This is not the case. I have already posted my own simple arithmetical equation (that incorporates assumptions reflecting my actual environmental conditions), which was used in my calculations. Post installation tests by me (witnessed by astounded PEA managers) have confirmed the accuracy of my equation.

Actually, I did not assume that you ONLY used these dreadful "web cable calculators". I mentioned this for the benefit of all concerned. To all...DO NOT USE THEM!!! I didn't use them AT ALL, but I accept that you are talking to a wider audience also.

You state my supply is 380V. I never did - my supply is actually 415V. You indicate a required current of 32A per phase - where did this figure come from? A more correct figure would be 75A (25A per phase).

Unless I am mistaken, I don't see anywhere that you mentioned 415 volts. I have posted that whilst 220V is the normal supply here in Thailand, customers with their own transformers are contracted to receive 230V (at least, that's what my contract states) and that PEA can increase the voltage to 240V at the transformer (via the "taps"; to offset voltage drop). The reason why I assumed 380 volts (3 phase) was because you mentioned 230 volts (single phase.) To an electrical person, this means 220 volts. Why? Quite simply, if you were supplied with 415 volts 3 phase, your MINIMUM single phase voltage would be 240 volts. Exactly! And it is - at the transformer. It is quite common for energy suppliers to provide a higher than usual voltage (but still within acceptable limits) if the transformer leg/branch is lightly loaded. For example, it is quite common in Australia to have a single phase voltage of 250-260 volts due to a light transformer load. Australia does not supply 220 volts. It supplies 240 volts, although it should be 230 volts (IEC). To further back-up my assumptions, Thailand mostly uses a 380 volt 3 phase supply (220 volts single phase).

With regard to current, this is very simple. I simply did the following, as I would do with any new installation;

Wattage figures (approximate) supplied by you.

5 600 Watts divided by 220 = about 25.5 Amps.

(Future allowance) 25% of 25.5 Amps = about 6.4 Amps.

25.5 + 6.4 = 31.9 or close enough to 32 Amps.

Most sensible electricians would allow for this. Understood. Thank you.

BTW, 5.6 kW plus 20% = 7kW (this is your present max load per phase, is it not?) As stated, my current max. load is 3kW per phase, simply because that's what I'm limited too by my cable size and length.

You state I need 300mm² per phase. This is way over the top. Both my equation and PEA agree that I should have had 95mm² per phase. Even applying common sense, if 50mm² x3 is providing 9kW within the 5% voltage variance rule, 95mm² x3 is obviously going to provide just less than twice 9kW, i.e. it would provide my targeted 17kW.

To fall within the universally accepted "no more than 5% voltage drop" rule, your above results are flawed.

At one stage, the PEA recommended that you use 700mm squared cable (Aluminium aerials, I assume PVC insulated). Where did 700mm² come from? This is not far from the truth. BTW, I still stand by my calculation of 300mm squared Aluminium PVC insulated aerial cables to provide a no greater than 5% voltage drop under a maximum load of 32 Amps per phase. 1.5km is a VERY VERY long way to run low voltage cables. I agree, and so do PEA now - but I followed their advice at the time. Normally, this is considered uneconomical. A higher voltage would normally be used (11kV) to within an "economical" distance from the lower voltage load.

You must consider the info already presented by me (rather than assumed by you) and realise that a voltage drop of 13% of 240V results in approximately 209V, which represents a 5% drop against appliances rated at 220V and is therefore totally acceptable.

Unfortunately, I had alreadly assumed a supply voltage of 380 volts per phase, for obvious reasons as stated in the above posts.

My options are many but, since I can use welding units and most other farm equipment at the location of my transformer (all my [wife's] land) with no voltage drop issues, I am not forced to spend hundreds of thousands of baht to improve my situation.

Rgds

Khonwan

Australian Standards say that the neutral conductor minimum size shall be sized to that of the total current to be carried, where there is more than one active conductor. In other words, if the sum of your Active conductors provide a total of 45 Amps current, the neutral conductor must be sized the same (45 Amps). This means that the neutral conductor will be bigger than any of the paralleled conductors. The reason is that an "earth return circuit" (MEN or otherwise) is not considered a "normal" current carrying conductor. Its' sole purpose is to provide a "reduced impedance path" so that Protective Devices (circuit breakers) can operate quicker under fault conditions (within 0.4 seconds at rated voltage). In your situation, a 50mm squared neutral used with 3 x paralleled 50mm squared Active conductors is unacceptable (potentially dangerous, even though the neutral is/will be/could be earthed every 500m). An appropriately sized "hard" neutral is required to maintain system integrity.

"Fault Current" is a MAJOR consideration when sizing cables over long distance. The type of insulation, the method of cable installation, the type (Class) of Protective Devices used, all influence this. This also formed part of my previous calculation. I wonder, did any of your/Thai calculations include this?

With regard to Aluminium conductors, connections to, and joints in, aluminium conductors must be made using components specifically designed for the connection of aluminium conductors and techniques specified by the manufacturer. When connecting aluminium conductors, the following special factors associated with aluminium should be considered:

[a] Removal of the aluminium oxide film from the conductors.

The relative softness of aluminium.

[c] The different coefficient of linear expansion of aluminium and other metals.

[d] Avoiding contact with dissimilar metals that may initiate galvanic action.

Understood.

Khonwan, I'm sorry if I seemed to "take the piss" out of you. I have only ever tried to help people here but since the influx of many "experts", I've decided that my advice is no longer "freely" available. This is not to say that I require money. Sorry to see you feel like this - I would only ask that you read posts more carefully before responding to them but your responses ARE appreciated. I hope you continue to educate us. Thank you for your time.

[Crossy]

Khonwan, I'm sorry if I seemed to "take the piss" out of you. I have only ever tried to help people here but since the influx of many "experts", I've decided that my advice is no longer "freely" available. This is not to say that I require money. Sorry to see you feel like this - I would only ask that you read posts more carefully before responding to them but your responses ARE appreciated. I hope you continue to educate us. Thank you for your time.

I too went through a "who are these idiots, I can't be arsed with replying to them and end up having to explain Ohm and Kirchoff again" phase I even considered moving to the "Dark Side", it now seems that most of them seem to have decided not to post on the electrical threads. Many times in the past these threads degenerated into slanging matches (I think one even got closed)

I appreciate Elkangorito's reponses, his experience is much more current than my own (like 20 odd years more current), regulations change and we all make mistakes so "peer review" is important, neither of us have any issues whatever with having genuine errors pointed out and corrected

Keep posting Elk.

Edited April 5, 2008 by Crossy

[elkangorito]

I too went through a "who are these idiots, I can't be arsed with replying to them and end up having to explain Ohm and Kirchoff again" phase I even considered moving to the "Dark Side", it now seems that most of them seem to have decided not to post on the electrical threads. Many times in the past these threads degenerated into slanging matches (I think one even got closed)

I appreciate Elkangorito's reponses, his experience is much more current than my own (like 20 odd years more current), regulations change and we all make mistakes so "peer review" is important, neither of us have any issues whatever with having genuine errors pointed out and corrected

Keep posting Elk.

Crossy, I don't think I've taken sides. Maybe I'm on the "grey side/area?"

My intent was to make an example of Khonwans situation without belittling him. Apparently I failed in this regard & for this I apologise . He made an admirable effort in times when "accurate" information was not available.

His situation is a good example of how things can go "awry" if certain details are not covered. Unfortunately, the solution will be neither cheap nor functional without undergoing major changes (cable upgrade or load reduction). I see only one possible solution...he could add another 2 x 50mm squared cables (of the same type) per phase to his existing installation (a total of 3 cables per phase including neutral). Adding 1 or 3 cables is not recommended due to asymmetrical phase currents. In addition, the neutral must be upgraded likewise. This still will not meet the 300mm squared requirement but, since I don't know the actual Maximum Demand of his premises, it could very well cover his bum in the meantime.

Again, my apologies Khonwan but your situation presents an opportunity in which problems can be highlighted.

The amount of work/effort that an electrician must do to properly calculate Maximum Demand & thence calculate the size of supply cables, is not a small task by any means. For those who still think that this "correct" info is freely available, please bear in mind that a "professional" electrician will happily carry the burden of his calculations/work until such time that another person has changed his work. I am one of these people.

[Khonwan]

I too went through a "who are these idiots, I can't be arsed with replying to them and end up having to explain Ohm and Kirchoff again" phase I even considered moving to the "Dark Side", it now seems that most of them seem to have decided not to post on the electrical threads. Many times in the past these threads degenerated into slanging matches (I think one even got closed)

I appreciate Elkangorito's reponses, his experience is much more current than my own (like 20 odd years more current), regulations change and we all make mistakes so "peer review" is important, neither of us have any issues whatever with having genuine errors pointed out and corrected

Keep posting Elk.

Crossy, I don't think I've taken sides. Maybe I'm on the "grey side/area?"

My intent was to make an example of Khonwans situation without belittling him. Apparently I failed in this regard & for this I apologise . He made an admirable effort in times when "accurate" information was not available.

His situation is a good example of how things can go "awry" if certain details are not covered. Unfortunately, the solution will be neither cheap nor functional without undergoing major changes (cable upgrade or load reduction). I see only one possible solution...he could add another 2 x 50mm squared cables (of the same type) per phase to his existing installation (a total of 3 cables per phase including neutral). Adding 1 or 3 cables is not recommended due to asymmetrical phase currents. In addition, the neutral must be upgraded likewise. This still will not meet the 300mm squared requirement but, since I don't know the actual Maximum Demand of his premises, it could very well cover his bum in the meantime.

Again, my apologies Khonwan but your situation presents an opportunity in which problems can be highlighted.

The amount of work/effort that an electrician must do to properly calculate Maximum Demand & thence calculate the size of supply cables, is not a small task by any means. For those who still think that this "correct" info is freely available, please bear in mind that a "professional" electrician will happily carry the burden of his calculations/work until such time that another person has changed his work. I am one of these people.

Thanks, elkangorito. I only wish that I had had access to both you and Crossy before I trusted P.E.A.

Kind regards

Khonwan

[Crossy]

My intent was to make an example of Khonwans situation without belittling him. Apparently I failed in this regard & for this I apologise . He made an admirable effort in times when "accurate" information was not available.

Thanks, elkangorito. I only wish that I had had access to both you and Crossy before I trusted P.E.A.

Air well and truly cleared, excellent!! :D

BTW, my reference to the "Dark Side" was of course to another well known Thailand related site whose name may never be uttered within the hallowed corridors of Thaivisa (actually it gets killed by the naughty words filter).

[AsiaAviation]

Due to the large amount of people posting questions etc about the electrical wiring of their abode (house), I have decided to post some information that may be helpful. The information was totally created by myself & I am happy to answer any questions.

I have also recently requested information from the Thai Electrical Mechanical Contractors Association with regard to possible 'wiring rules' that may exist in Thailand. I'll keep people informed of any response from them.

The below attachment illustrates a domestic electrical system. I have based it upon the NZ/AS 3000:2000 Wiring Rules (Australia). I hope it is easy for laymen to understand. My ultimate hope is that it will help to put an end to the numerous posts in different forum topics. For example, people who have problems with sensitive equipment (computers, stereos etc) generally will not associate their problem with that of an electrical nature. Since this could be the case, I thought it a good idea to begin this post.

How do I download the attachemnt?

[elkangorito]

I have removed the attachments.

Most of my attachments were used in this website, which should help you greatly

http://www.crossy.co.uk/wiring/

[Artisi]

I have removed the attachments.

Most of my attachments were used in this website, which should help you greatly

http://www.crossy.co.uk/wiring/

Crossy

Just a little "nit-pick" on your excellent info. - in the above link in the chapter on cable size /capacity, I feel it would be a good move to highlight / discuss cable length as not everyone would be aware of the relationship between length/ area / capacity.

[stickyb]

Here's an interesting example from a friend near Buriram. His house has just been finished, and we went up there a few days ago for the house blessing and party.

He has been very careful to specify to the electrician that he wanted all sockets properly earthed, etc. When he came to check, the only snag was that the electrician told him that the builders had poured concrete over the earth rod, so it was no longer visible. Hmmmmm.

For the Isaan style party, the stage crew tapped directlt into the supply on the electrical pole outside his property, on the outlet from the meter. Whilst they were setting up, he went to have a shower and came back very quickly complaining that he had just had a shock from the shower tap. I went to check the circuit breaker box, and found that the box itself was live.

What had happened was that the stage crew had reversed live and neutral when reconnecting the wires to the meter, and inside the circuit box was a cable linking the neutral bus bar and the earth bus bar, hence every earted item becoming live. The earth connection to the ground rod did nothing to stop this. Very nasty.

He is now waiting for the electrician to return and check/correct.

[Crossy]

What had happened was that the stage crew had reversed live and neutral when reconnecting the wires to the meter, and inside the circuit box was a cable linking the neutral bus bar and the earth bus bar, hence every earted item becoming live. The earth connection to the ground rod did nothing to stop this. Very nasty.

Nasty indeed!

The link between ground and neutral (the MEN link) is important for safe operation (and required by local regulations), unfortunately it does not protect against deliberate sabotage. The ground rod resistance (if indeed it exists) may not pull enough current to drop the (60A) incoming breaker and the MEN link does not pass through the ELCB so that won't save you either.

I'm just glad that nobody was injured/killed

This type of wiring error is one reason that MEN (or PME as we call it) is not implemented in the UK on buildings with overhead supply cables, underground supply uses the cable armour as the ground (it's linked to the neutral at the transformer) so a miswire of this nature will become immediately obvious.

Long ago we had a similar incident (in Korea), the chaps replaced a 4 pole (3-phase) breaker, in the process they transposed neutral and one phase, resulting in 2/3 of our outlets giving 380V --> a bang big enough to create a new universe!

Edited May 14, 2008 by Crossy

[dotcom]

HUH? Ground & Neutral should be connected? Not in my system.

I was under the assumption that neutral returns to the grid & hence (in theory) to the power station.

Please correct me if I am wrong.

As mentioned before I can read small amounts of current between my neutral & ground with mulitmeter set to the lowest A/C setting. +/-4 volts A/C.

[Crossy]

HUH? Ground & Neutral should be connected? Not in my system.

I was under the assumption that neutral returns to the grid & hence (in theory) to the power station.

Please correct me if I am wrong.

As mentioned before I can read small amounts of current between my neutral & ground with mulitmeter set to the lowest A/C setting. +/-4 volts A/C.

It depends upon your actual arrangements. Do a Google on Multiple Earthed Neutral (MEN) or Protective Multiple Earthing (PME), both are pretty similar although not identical and both have a link between the ground bar and the incoming neutral.

The neutral is (should be) always grounded at the substation / transformer, it's this connection that defines its potential with respect to ground and it's this path that causes current to flow should there be an inadvertent (you) connection between live and ground.

If you have a 'TT' system (no N-E link) then you will invariably see a small potential between ground and neutral. You may also find that a live-casework fault will not take out the overcurrent device because the ground resistance is too high to pull enough current (it will however drop an ELCB, hope you have one).

The MEN/PME system is safer in that it provides a guaranteed low-impedence path between the metalwork of your appliances and the grounded side of the transformer. Unfortunately, if miswired (as happened to the poster above) it can introduce hazardous voltages to what would normally be earthed items.

Edited May 15, 2008 by Crossy

[dotcom]

Exact same thing happened to me. I arranged with MEA to come out & upgrade my power meter to 30/100.

The fools wired it up backwards. They couldn't care less.

I forget right now how I discovered the mistake. I did however correct it.

Yes Crossy I insist on Safe-T-Cut

[dotcom]

Shouldn't the neutral bus be isolated from the metal enclosure? (In the load center).

[Crossy]

Shouldn't the neutral bus be isolated from the metal enclosure? (In the load center).

In your particular case, a TT system (no MEN/PME link) the neutral will not be connected to the casework.

In a MEN/PME system the casework being linked to the ground bar will end up linked to the neutral via the MEN link.

The neutral should never get more than a few volts above ground (unless miswired) so there is no danger in having this link, indeed it is considered a highly safe installation. What is supposed to happen is that the neutral is linked to ground at many points (the individual earth rods) as well as at the transformer meaning that there can be no single point of failure and the neutral should remain near ground.

Note that MEN/PME protects against a FAILURE, it cannot protect you against some plonker wiring it up wrong

Edited May 16, 2008 by Crossy

[Crossy]

We have just taken delivery of a new Whirlpool washing machine after the previous unit was declared beyond repair by our pet repair chap (it did make quite a big bang).

A pleasant buying experience in Homepro (well the THREE trainee sales girls were cute) was followed by prompt delivery and installation.

The old machine had a Schuko plug for which I'd installed the correct socket, the new machine has the plug pictured below:-

Interesting, I've not seen anything quite like it before and it's not on the usual 'international electricity' sites. It fits the regular Thai 'universal' grounded outlet perfectly (which the installation chaps re-fitted for us after I'd found it), so it's 1,000,000 times better than the Schuko that was fitted to the old machine, although it really looks like it's intended to fit a recessed outlet.

Anyone seen these elsewhere, or are they a strange hybrid dreamed up by the Thais to confuse everyone even more?

Looks very similar to the old UK 5A (still used in India) but the ground is the same size as the L and N pins and is closer to them, 5A plug pictured below for comparison.

Edited May 23, 2008 by Crossy

[lopburi3]

I am very sure it is the same as I used in Germany back in the 60's and what I expected when I first started to see the recessed socket Schuko plugs sold here.

[longball53098]

Maybe the Whirlpool factory did an inventory and they found a few cases of these old plugs way back in the stock room and someone said use them on the Thai appliances and no one will no the difference? They saved a ton of baht on ordering new cords for that run of washers.

[thaipaw]

Crossy,

I'm new to these forums, but I've spent the better part of the past couple days reading through this thread and your oft-referenced website. I'm currently in Chiang Mai, but getting ready to move to northeast Cambodia, into a rented house that I've visited once. Upon seeing the state of the wiring there, I vowed to completely redo the wiring. I might hire a local handyman to do some of the labor, but there is no one in that part of the country that I would trust with making any decisions about electrical systems.

I've often seen mention of a MEN system or link, but I'm not sure exactly what is meant by that. Several months ago, you wrote saying "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."

What exactly are the potential hazards? (Other than the problems recently described where a reversal of the line and neutral connections causes metal appliance cabinets to become "hot".)

I'd normally test for such a reversal by ensuring that multimeter shows ~230V only between line/neutral and line/ground. But it occurs to that if the ground and "neutral" are tied together (i.e. wiht a MEN link), then such a test would show nothing abnormal. So how do you safely test for this? How could a system be wired to prevent damage/injury (or at least give notice) if a reversal were to accidently occur?

For a homeowner's purposes, is it safe to equate "MEN" with any design that connnects the neutral and ground to a shared grounding rod at the home's distribution point (as has long been commonly done in the US), or is there something else that makes this system unique?

Assuming that the local system in northeast Cambodia is not designed to use MEN, then would I be better off NOT connecting my neutral to ground AT ALL (i.e. line and neutral connect to the pole outside, the ground wire connects to a rod in the ground, and no link between ground and neutral)?