3 Phase Electric

[Naam]

And another useless post (as indeed is this one, of course).

i am quite impressed by the usefulness of your posts Sir. especially appreciated is your advice for personal behaviour which i might have followed strictly in future if there hadn't been the tiny caveat fact that you are not able to distinguish between "sarcasm" and "irony" or... you most probably don't know that there is a big difference.

once you have acquired that knowledge AND realize that my irony wasn't directed at you i will grant you the right to address me again. however, i have second thoughts about being addressed as "smartass".

[marc11]

I would just like to add my experience with 3 phase.

While building the house we told the electrician that we wanted to install many A/C units in different rooms amongst other appliances at a later date, he said oh you’ll need 3 phase and gave us an estimate of 58000 bt, this was to include 3 phase from the main road up to (which was to be installed by the local elec company) and in the house (done by the electrician). I was not around during the installation and it wouldn’t have mattered as I don’t know much about elec wiring etc anyway. Needless to say the day came when we wanted to install the A/C units (2 years later), the A/C company came round to take a look at the wiring etc in the house and promptly told us we only have single phase in the house and from the main road, was I surprised "No" pissed off that I had been ripped off, you bet. I don't know what the answer would have been to prevent this happening as we had employed the electrician to do his job, we have tried to locate him but as you can imagine this is proving very difficult and a complete waste of time.

[Khonwan]

I would just like to add my experience with 3 phase.

While building the house we told the electrician that we wanted to install many A/C units in different rooms amongst other appliances at a later date, he said oh you’ll need 3 phase and gave us an estimate of 58000 bt, this was to include 3 phase from the main road up to (which was to be installed by the local elec company) and in the house (done by the electrician). I was not around during the installation and it wouldn’t have mattered as I don’t know much about elec wiring etc anyway. Needless to say the day came when we wanted to install the A/C units (2 years later), the A/C company came round to take a look at the wiring etc in the house and promptly told us we only have single phase in the house and from the main road, was I surprised "No" pissed off that I had been ripped off, you bet. I don't know what the answer would have been to prevent this happening as we had employed the electrician to do his job, we have tried to locate him but as you can imagine this is proving very difficult and a complete waste of time.

I'm not sure you should trust the A/C guy any more than than that "electrician". How many cables go into your meter?

[ProThaiExpat]

I diligently read almost every one of the 92 posts in this thread to make sure I am not missing something, so if I have, please be kind.

I saw nowhere the mention of the "demand", in general, that an appliance requires. Perhaps the ohms, watts or volts tell it all, but for us "civilians" without electrical engineering degrees or manuals on our bookshelves, a simpler approach would be helpful.

When I built my house, the developer and most falangs in the developemnt opted for 3 phase systems as the developers experience was that most falang have so much "demand" for electricity that three phase was worth the initial investment. More expensive panel, more expensive meter and connection charge but well worth it when high demand is present and when electric power diminishes from the utility.

I do know that "resistance" type of appliances, ie. toasters, hot water kettles, hot water heaters in bathrooms, electric clothes dryers, hair dryers, etc. draw a great deal more power than simple motors. Since I have two Siemens Automatic Electric water heaters (by the way, they are three phase) and an electric clothes dryer as well as many "resistance coil" small applicances, I went along with the initial additional cost of a 3 phase.

My system never goes down due to too much "demand" and I thank the electric gods for the three phase when the power supply for our development diminishes and only parts of my house have electricity.

The number of electic outlets, outside kitchen, hair dryers etc. have only increased since I moved in, but I do not worry as the three phase will cover any addition or add ons.

Since 3 phase doesn't increase your electric bill, it seems to me that any quality home of 200 sq. meters or larger for a falang should be three phase. My guess is that the three phase cost me about 60k more than two phase.

[elkangorito]

I would just like to add my experience with 3 phase.

While building the house we told the electrician that we wanted to install many A/C units in different rooms amongst other appliances at a later date, he said oh you’ll need 3 phase and gave us an estimate of 58000 bt, this was to include 3 phase from the main road up to (which was to be installed by the local elec company) and in the house (done by the electrician). I was not around during the installation and it wouldn’t have mattered as I don’t know much about elec wiring etc anyway. Needless to say the day came when we wanted to install the A/C units (2 years later), the A/C company came round to take a look at the wiring etc in the house and promptly told us we only have single phase in the house and from the main road, was I surprised "No" pissed off that I had been ripped off, you bet. I don't know what the answer would have been to prevent this happening as we had employed the electrician to do his job, we have tried to locate him but as you can imagine this is proving very difficult and a complete waste of time.

Marc, it may be that only the 3 phase "supply" was installed but your installation was not wired using the 3 phases. The way to tell if you have 3 phase distributed within your home is to see how many cables go into your main distribution board (breaker box) from the supply. There should be 4 cables - 3 phases & a neutral. The 3 'active' phases will go into the top of your main switch (or main circuit breaker).

I'm not sure you should trust the A/C guy any more than than that "electrician". How many cables go into your meter?

The amount of cables that go into your kilowatt hour meter will not tell you if your installation has been wired using the 3 phases.

ProThaiExpat, my comments in red (easier to see against blue).

I diligently read almost every one of the 92 posts in this thread to make sure I am not missing something, so if I have, please be kind.

I saw nowhere the mention of the "demand", in general, that an appliance requires. Perhaps the ohms, watts or volts tell it all, but for us "civilians" without electrical engineering degrees or manuals on our bookshelves, a simpler approach would be helpful.

Maximum Demand was actually mentioned in post number 10 & from then on at various stages.

When I built my house, the developer and most falangs in the developemnt opted for 3 phase systems as the developers experience was that most falang have so much "demand" for electricity that three phase was worth the initial investment. More expensive panel, more expensive meter and connection charge but well worth it when high demand is present and when electric power diminishes from the utility.

Not all farangs actually require 3 phase. If a Maximum Demand calculation is done BEFORE the home is wired, it may prove that single phase will suffice. As a general rule, anything above an 80 amp demand may require 3 phase. Anything OVER 100 amps WILL require 3 phase. When I do a Maximum DEmand calculation, I always allow about 20% extra load for future expansion.

I do know that "resistance" type of appliances, ie. toasters, hot water kettles, hot water heaters in bathrooms, electric clothes dryers, hair dryers, etc. draw a great deal more power than simple motors. Since I have two Siemens Automatic Electric water heaters (by the way, they are three phase) and an electric clothes dryer as well as many "resistance coil" small applicances, I went along with the initial additional cost of a 3 phase.

My system never goes down due to too much "demand" and I thank the electric gods for the three phase when the power supply for our development diminishes and only parts of my house have electricity.

The number of electic outlets, outside kitchen, hair dryers etc. have only increased since I moved in, but I do not worry as the three phase will cover any addition or add ons.

Since 3 phase doesn't increase your electric bill, it seems to me that any quality home of 200 sq. meters or larger for a falang should be three phase. My guess is that the three phase cost me about 60k more than two phase.

I am of the opinion that a "normal" farang home should have a minimum 80 amp single phase supply. This will be more than enough for the average farang & his/her family.

[Khonwan]

"The amount of cables that go into your kilowatt hour meter will not tell you if your installation has been wired using the 3 phases."

elkangorito

That's a statement of the obvious! It is, however, a quick way to see if he has a three-phase SUPPLY or not. His actual supply starts at his kWh meter. What he has at his domestic consumer box SHOULD reflect this, but this is Thailand - it may not! It is completely possible that he has a 3-phase meter with only one phase (two wires, for the benefit of ProThaiExpat) running to his consumer box. This possibility is all the more feasible (though not justifiable) if the "electrician" knew the A/C units were not going to be installed immediately. The OP states they were installed two years later. Check the meter!

[elkangorito]

"The amount of cables that go into your kilowatt hour meter will not tell you if your installation has been wired using the 3 phases."

elkangorito

That's a statement of the obvious! It is, however, a quick way to see if he has a three-phase SUPPLY or not. His actual supply starts at his kWh meter. What he has at his domestic consumer box SHOULD reflect this, but this is Thailand - it may not! It is completely possible that he has a 3-phase meter with only one phase (two wires, for the benefit of ProThaiExpat) running to his consumer box. This possibility is all the more feasible (though not justifiable) if the "electrician" knew the A/C units were not going to be installed immediately. The OP states they were installed two years later. Check the meter!

I have a friend in Klaeng who has a 3 phase supply but only a single phase installation. Strange but true.

[Khonwan]

I am of the opinion that a "normal" farang home should have a minimum 80 amp single phase supply. This will be more than enough for the average farang & his/her family.

Many, however, may find themselves with a supply from a 20kVA transformer, already servicing too many houses.

[elkangorito]

I am of the opinion that a "normal" farang home should have a minimum 80 amp single phase supply. This will be more than enough for the average farang & his/her family.

Many, however, may find themselves with a supply from a 20kVA transformer, already servicing too many houses.

What are your recommendations in this regard?

[Khonwan]

I am of the opinion that a "normal" farang home should have a minimum 80 amp single phase supply. This will be more than enough for the average farang & his/her family.

Many, however, may find themselves with a supply from a 20kVA transformer, already servicing too many houses.

What are your recommendations in this regard?

That depends on whether there is a 3-ph supply or not. There wasn't in my village before I paid (50/50 with the government) for a third high voltage cable to be run 4.3km from the next village. If there was an existing 3-ph low-voltage (220V) supply available, I'd certainly suggest installing a 3-ph supply.

Since the presence of a 20kVA transformer would probably indicate only single-phase low voltage (220V) cables available, I would suggest installing a 30kVA single-ph transformer to the high voltage supply. If the high voltage cables were adjacent to the property, you should expect to pay around 120,000 baht (as of a around two years ago) for the transformer and two concrete poles, inclusive of installation.

[Nawtilus]

Anyone know the cost of solar system as compared to the regular electric hot water system and connection.

Is there any extra work/cost involved with the solar system ?

I require hot water to 4 points in the house, how big a solar system is required...the 4 points are...kitchen, kids bathroom, laundry and master bathroom which has a small jacuzzi in it.

[Khonwan]

Anyone know the cost of solar system as compared to the regular electric hot water system and connection.

Is there any extra work/cost involved with the solar system ?

I require hot water to 4 points in the house, how big a solar system is required...the 4 points are...kitchen, kids bathroom, laundry and master bathroom which has a small jacuzzi in it.

I don't know - I just allow the sun to heat the water in dedicated water pipes from my water-tower to the house for hot showers (VERY cheap).

The reason for my reply, however, is to suggest you start a new topic since you'll attract, IMO, many more views than this 3-phase topic is likely to.

Rgds

Khonwan

[LoveDaBlues]

Okay, I'm in the early stages of buiding a house. I have the plans drawn but haven't had a chance

to calculate the electric needed; figured the builder would know but Tit and I want more than

a "guess". I have talked to him briefly about the power and the house will be wired with

a ground wire and not just the 2-wire system. That's as far as I got on the subject of the power

needs.

I guess the place to start would be to list the electric draws and let those with much more

experience take a crack at it.

Note: I drew the plans up using feet and converted to meters for the builder. I'm listing feet here.

Also, I plan on having a diesel generater for the few occasions when the power is out or 'diminished'

as happens here.

a/c units = 5 total.

(1) bedroom 12' X 11'

(2) bedroom 12' X 11'

(3) master bedroom 16' X 15'

(4) home theater 16' X 13'

(5) family room 22'' X 17'

3 on-demand water heaters 6kw each (the box-thingys in shower)

8 ceiling fans

1 clothes washer

1 on-demand water pump (sufficient for single-story house)

kitchen with standard stuff: fridge, hood over gas range

figure 20 double-socket outlets

standard amount of lights in each room

Don't think I've missed any major power draws; just looking for a "rough" estimate of

what I need. I hope I can go with a single phase set-up.

BTW, what is the largest service panel I can get here assuming single phase?

I know very little about electricity so if I said someone wrong it's not because I'm

stupid it's because I'm ignorant.

[elkangorito]

Okay, I'm in the early stages of buiding a house. I have the plans drawn but haven't had a chance

to calculate the electric needed; figured the builder would know but Tit and I want more than

a "guess". I have talked to him briefly about the power and the house will be wired with

a ground wire and not just the 2-wire system. That's as far as I got on the subject of the power

needs.

I guess the place to start would be to list the electric draws and let those with much more

experience take a crack at it.

Note: I drew the plans up using feet and converted to meters for the builder. I'm listing feet here.

Also, I plan on having a diesel generater for the few occasions when the power is out or 'diminished'

as happens here.

a/c units = 5 total.

(1) bedroom 12' X 11'

(2) bedroom 12' X 11'

(3) master bedroom 16' X 15'

(4) home theater 16' X 13'

(5) family room 22'' X 17'

3 on-demand water heaters 6kw each (the box-thingys in shower)

8 ceiling fans

1 clothes washer

1 on-demand water pump (sufficient for single-story house)

kitchen with standard stuff: fridge, hood over gas range

figure 20 double-socket outlets

standard amount of lights in each room

Don't think I've missed any major power draws; just looking for a "rough" estimate of

what I need. I hope I can go with a single phase set-up.

BTW, what is the largest service panel I can get here assuming single phase?

I know very little about electricity so if I said someone wrong it's not because I'm

stupid it's because I'm ignorant.

I'll do a maximum demand calculation (tonight), based on your list but I will have other recommendations for you.

[Gary A]

I would guess that single phase is enough for MOST houses. If you have equipment that needs three phase that would be a different story. I base this on the fact that a friend of mine has a large villa. He has single phase. He has three fairly large air conditioners, four refrigerators, a large electric water heater and several microwave ovens. His swimming pool has two filters, both about 1,200 watts each as well as a 1,000 watt pump for a jacuzzi. He also has two well water pumps and MANY lights. He is a former British electrician and has no choice because three phase is not available out in the boonies.

[Khonwan]

I would guess that single phase is enough for MOST houses. If you have equipment that needs three phase that would be a different story. I base this on the fact that a friend of mine has a large villa. He has single phase. He has three fairly large air conditioners, four refrigerators, a large electric water heater and several microwave ovens. His swimming pool has two filters, both about 1,200 watts each as well as a 1,000 watt pump for a jacuzzi. He also has two well water pumps and MANY lights. He is a former British electrician and has no choice because three phase is not available out in the boonies.

Does he have his own transformer?

[elkangorito]

I would guess that single phase is enough for MOST houses. If you have equipment that needs three phase that would be a different story. I base this on the fact that a friend of mine has a large villa. He has single phase. He has three fairly large air conditioners, four refrigerators, a large electric water heater and several microwave ovens. His swimming pool has two filters, both about 1,200 watts each as well as a 1,000 watt pump for a jacuzzi. He also has two well water pumps and MANY lights. He is a former British electrician and has no choice because three phase is not available out in the boonies.

A lot of people here in Thailand end up confused about the size of their electrical supply, I guess mainly due to the lack of information/service by the Thai energy authorities.

Unless you intend to use lots of electric motors (each 2kW+), have a 2 or 3 story mansion with 4 bathrooms, a bloody great kitchen & shitloads of hot water, there is generally no need for a 3 phase supply (excluding equipment that requires 3 phase, as you said). To cover your bum & to avoid buggerising around in the future, an 80 amp single phase supply is ample for a 'normal' abode. Besides, 3 phase service will not serve you well unless it is distributed appropriately throughout the installation.

[elkangorito]

Okay, I'm in the early stages of buiding a house. I have the plans drawn but haven't had a chance

to calculate the electric needed; figured the builder would know but Tit and I want more than

a "guess". I have talked to him briefly about the power and the house will be wired with

a ground wire and not just the 2-wire system. That's as far as I got on the subject of the power

needs.

I guess the place to start would be to list the electric draws and let those with much more

experience take a crack at it.

Note: I drew the plans up using feet and converted to meters for the builder. I'm listing feet here.

Also, I plan on having a diesel generater for the few occasions when the power is out or 'diminished'

as happens here.

a/c units = 5 total.

(1) bedroom 12' X 11'

(2) bedroom 12' X 11'

(3) master bedroom 16' X 15'

(4) home theater 16' X 13'

(5) family room 22'' X 17'

3 on-demand water heaters 6kw each (the box-thingys in shower)

8 ceiling fans

1 clothes washer

1 on-demand water pump (sufficient for single-story house)

kitchen with standard stuff: fridge, hood over gas range

figure 20 double-socket outlets

standard amount of lights in each room

Don't think I've missed any major power draws; just looking for a "rough" estimate of

what I need. I hope I can go with a single phase set-up.

BTW, what is the largest service panel I can get here assuming single phase?

I know very little about electricity so if I said someone wrong it's not because I'm

stupid it's because I'm ignorant.

Based on your supplied info;

Legend; GPO - General Purpose Outlet (power point). SGPO - single general purpose outlet (1 x plug point per fitting). DGPO - double general purpose outlet (2 x plug fittings per outlets).

RCD/CB - combination earth leakage device with circuit breaker rated at 30mA 20mS, not adjustable, installed into the MDB- -. MDB - Main Distribution Board (breaker box). 2C+E - 2 core and earth PVC/PVC cable rated at 300 volts, 70 degrees C.

Assumptions.

- all a/c units are single phase <10 amps.

- all lighting will be either fluorescent or incandescent, not exceeding 60 watts total per light fitting.

- washing machine is the 'plug-in' type.

- water pump is the 'plug-in' type.

- no GPO's installed in any bathroom.

- no external (outside) GPO's, except for pump.

- all electrical equipment is single phase.

- you are not in a rural area.

Building Construction scope.

3 x bedrooms, 1 x theatre room, 1 x family room, 3 x bathrooms, 1 x laundry, 1 x kitchen.

Maximum Demand calculation.

Power.

2 x small bedrooms - 2 x SGPO's + 1 x a/c per bedroom.

1 x master bedroom - 4 x SGPO's + 1 x a/c.

1 x family room - 4 x SGPO's + 1 x a/c.

1 x home theatre room - 4 x SGPO's + 1 x a/c.

1 x laundry - 1 x DGPO.

1 x kitchen - 3 x DGPO's, 2 x SGPO's (allowance for an extra 10 amp allowance - AS/NZS 3000:2000 Table C, load group C).

1 x pump - 1 x SGPO.

Total estimated GPO load - 25 amps.

Water Heaters.

3 x 6kW instantaneous hot water service - 33.3% of total load - = 33.3% of 18kW = 27 Amps.

Total estimated water heater load - 27 amps.

Lighting.

2 x small bedrooms - 1 x light fitting each.

1 x master bedroom - 2 x light fittings.

1 x family room - 2 x light fittings.

1 x theatre room - 4 x light fittings.

1 x laundry - 1 x light fitting.

1 x kitchen - 2 x light fittings.

3 x bathrooms - 1 x light fitting each.

Outside lighting - 2 x light fittings.

8 x ceiling fans (permanently fixed ceiling fans are classified as light fittings as long as each fan does not exceed 150 Watts.

Total estimated lighting load - 5 amps.

Total Maximum Demand = power+lighting+water heaters=57 amps.

Total Maximum Demand plus allowance for a 20% future increase in load = 68 amps.

3 phase supply not required.

Minimum cable sizes & corresponding maximum RCD/CB sizes.

Power circuits - 2.5mm squared 2C+E, 20 amp RCD/CB.

Lighting circuits - 1.5mm squared 2C+E, 15 amp RCD/CB.

Water heaters - 6mm squared 2C+E, 30/32 amp RCD/CB.

KWH Meter (single phase).

Opt for a 100 amp (maximum current) meter because to my knowledge, the next lowest maximum size is 60 amps.

Circuit distribution.

All bedrooms placed on 1 x 20 amp RCD/CB (power circuit).

Family room, theatre & laundry placed on 1 x 20 amp RCD/CB (power circuit).

Kitchen placed on 1 x 20 amp RCD/CB (power circuit).

Each water heater has its own 30/32 amp RCD/CB.

All lighting placed on 1 x 15 amp CB (not earth leakage, although this decision is up to your discretion).

Notes.

- Main Circuit Breaker should not exceed 80 amps & should not be earth leakage.

- All RCD/CB's & CB's should have a minimum Fault Current Interrupt Capacity of 6kA (6000 amps).

- The M.E.N. system should be employed.

- I suggest the purchase of a minimum 30 pole Main Distribution Board (breaker box).

- I suggest using Square D, Merlin Gerin or Clipsal products.

[chownah]

Why should the main breaker be limited to 80 amps....seems to me that bigger would not cause a problem?...would it?...and if so what problem?

Chownah

[Crossy]

Elkangorito. Would a split-service consumer unit using a single ELCB not provide sufficient protection for the power circuits and water heaters at a lower cost than individual ELCBs for each circuit?

I think Thai electricians would stand a better chance of hooking it up correctly

[elkangorito]

Why should the main breaker be limited to 80 amps....seems to me that bigger would not cause a problem?...would it?...and if so what problem?

Chownah

Since I believe that the KWH meter to be used should be 100 amps & since these KWH meters do not have built-in overcurrent protection, the only thing that will prevent damage to the KWH meter is the MCB (Main Circuit Breaker). The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. In most installations (not in Thailand), the energy authority protects their KWH meter with an HRC fuse, aka the 'consumers fuse' or the 'service fuse'. This fuse is located before the KWH meter & is usually to BS 88 or BS 1361 standard. Its job is to protect the consumers mains from overload & to limit the fault current to the domestic installation. These fuses are normally rated the same (or slightly less) as the current carrying capacity as the consumers mains.

Elkangorito. Would a split-service consumer unit using a single ELCB not provide sufficient protection for the power circuits and water heaters at a lower cost than individual ELCBs for each circuit?

I think Thai electricians would stand a better chance of hooking it up correctly

You're probably right Crossy but in any case, I think the kitchen should have its own dedicated RCD/CB. Of course, all the other circuits could be protected by another RCD/CB. As you know, the only potential problem is nuisance tripping as equipment gets older.

Do you know how many pole spaces an RCD/CB uses in a DB? Is it 2 or 2.5? I forget.

[Crossy]

Do you know how many pole spaces an RCD/CB uses in a DB? Is it 2 or 2.5? I forget.

The Square-D Multi-9 Series DPN-N VIGI module (combined MCB and RCD) are 36mm wide (two 18mm pole spaces).

IIRC older units were 45mm (2.5 pole spaces).

Edited March 21, 2007 by Crossy

[Gary A]

I would guess that single phase is enough for MOST houses. If you have equipment that needs three phase that would be a different story. I base this on the fact that a friend of mine has a large villa. He has single phase. He has three fairly large air conditioners, four refrigerators, a large electric water heater and several microwave ovens. His swimming pool has two filters, both about 1,200 watts each as well as a 1,000 watt pump for a jacuzzi. He also has two well water pumps and MANY lights. He is a former British electrician and has no choice because three phase is not available out in the boonies.

Does he have his own transformer?

Yes the transformer belongs to him. I forgot how much he paid for it but it WAS expensive.

[chownah]

Why should the main breaker be limited to 80 amps....seems to me that bigger would not cause a problem?...would it?...and if so what problem?

Chownah

Since I believe that the KWH meter to be used should be 100 amps & since these KWH meters do not have built-in overcurrent protection, the only thing that will prevent damage to the KWH meter is the MCB (Main Circuit Breaker). The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. In most installations (not in Thailand), the energy authority protects their KWH meter with an HRC fuse, aka the 'consumers fuse' or the 'service fuse'. This fuse is located before the KWH meter & is usually to BS 88 or BS 1361 standard. Its job is to protect the consumers mains from overload & to limit the fault current to the domestic installation. These fuses are normally rated the same (or slightly less) as the current carrying capacity as the consumers mains.

It seems that a 100 amp main circuit breaker would be the right size to protect the KWH meter since they are both 100 amp rated....so I'm still not seeing why you indicated that 80 amps is the max main circuit breaker to be used....what problem does the 100 amp main circuit breaker cause...I still don't get it. In your post you said " The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. "...I can't tell if you are saying that a 100 amp beaker is not good because of the 100 amp meter rating or if you are saying he onliy needs 80 amps so a 100 amp breaker is not necessary. When I got my service (with a 100 amp meter) I was told that a 100 amp main circuit breaker was the largest I should use....and that's what I've got...so I'm trying to anticipate what problem this may cause. The advantage of the 100 amp breaker is more room for future build out compared to an 80 amp breaker.

Edited March 21, 2007 by chownah

[LoveDaBlues]

Okay, I'm in the early stages of buiding a house. I have the plans drawn but haven't had a chance

to calculate the electric needed; figured the builder would know but Tit and I want more than

a "guess". I have talked to him briefly about the power and the house will be wired with

a ground wire and not just the 2-wire system. That's as far as I got on the subject of the power

needs.

I guess the place to start would be to list the electric draws and let those with much more

experience take a crack at it.

Note: I drew the plans up using feet and converted to meters for the builder. I'm listing feet here.

Also, I plan on having a diesel generater for the few occasions when the power is out or 'diminished'

as happens here.

a/c units = 5 total.

(1) bedroom 12' X 11'

(2) bedroom 12' X 11'

(3) master bedroom 16' X 15'

(4) home theater 16' X 13'

(5) family room 22'' X 17'

3 on-demand water heaters 6kw each (the box-thingys in shower)

8 ceiling fans

1 clothes washer

1 on-demand water pump (sufficient for single-story house)

kitchen with standard stuff: fridge, hood over gas range

figure 20 double-socket outlets

standard amount of lights in each room

Don't think I've missed any major power draws; just looking for a "rough" estimate of

what I need. I hope I can go with a single phase set-up.

BTW, what is the largest service panel I can get here assuming single phase?

I know very little about electricity so if I said someone wrong it's not because I'm

stupid it's because I'm ignorant.

Based on your supplied info;

Legend; GPO - General Purpose Outlet (power point). SGPO - single general purpose outlet (1 x plug point per fitting). DGPO - double general purpose outlet (2 x plug fittings per outlets).

RCD/CB - combination earth leakage device with circuit breaker rated at 30mA 20mS, not adjustable, installed into the MDB- -. MDB - Main Distribution Board (breaker box). 2C+E - 2 core and earth PVC/PVC cable rated at 300 volts, 70 degrees C.

Assumptions.

- all a/c units are single phase <10 amps.

- all lighting will be either fluorescent or incandescent, not exceeding 60 watts total per light fitting.

- washing machine is the 'plug-in' type.

- water pump is the 'plug-in' type.

- no GPO's installed in any bathroom.

- no external (outside) GPO's, except for pump.

- all electrical equipment is single phase.

- you are not in a rural area.

Building Construction scope.

3 x bedrooms, 1 x theatre room, 1 x family room, 3 x bathrooms, 1 x laundry, 1 x kitchen.

Maximum Demand calculation.

Power.

2 x small bedrooms - 2 x SGPO's + 1 x a/c per bedroom.

1 x master bedroom - 4 x SGPO's + 1 x a/c.

1 x family room - 4 x SGPO's + 1 x a/c.

1 x home theatre room - 4 x SGPO's + 1 x a/c.

1 x laundry - 1 x DGPO.

1 x kitchen - 3 x DGPO's, 2 x SGPO's (allowance for an extra 10 amp allowance - AS/NZS 3000:2000 Table C, load group C).

1 x pump - 1 x SGPO.

Total estimated GPO load - 25 amps.

Water Heaters.

3 x 6kW instantaneous hot water service - 33.3% of total load - = 33.3% of 18kW = 27 Amps.

Total estimated water heater load - 27 amps.

Lighting.

2 x small bedrooms - 1 x light fitting each.

1 x master bedroom - 2 x light fittings.

1 x family room - 2 x light fittings.

1 x theatre room - 4 x light fittings.

1 x laundry - 1 x light fitting.

1 x kitchen - 2 x light fittings.

3 x bathrooms - 1 x light fitting each.

Outside lighting - 2 x light fittings.

8 x ceiling fans (permanently fixed ceiling fans are classified as light fittings as long as each fan does not exceed 150 Watts.

Total estimated lighting load - 5 amps.

Total Maximum Demand = power+lighting+water heaters=57 amps.

Total Maximum Demand plus allowance for a 20% future increase in load = 68 amps.

3 phase supply not required.

Minimum cable sizes & corresponding maximum RCD/CB sizes.

Power circuits - 2.5mm squared 2C+E, 20 amp RCD/CB.

Lighting circuits - 1.5mm squared 2C+E, 15 amp RCD/CB.

Water heaters - 6mm squared 2C+E, 30/32 amp RCD/CB.

KWH Meter (single phase).

Opt for a 100 amp (maximum current) meter because to my knowledge, the next lowest maximum size is 60 amps.

Circuit distribution.

All bedrooms placed on 1 x 20 amp RCD/CB (power circuit).

Family room, theatre & laundry placed on 1 x 20 amp RCD/CB (power circuit).

Kitchen placed on 1 x 20 amp RCD/CB (power circuit).

Each water heater has its own 30/32 amp RCD/CB.

All lighting placed on 1 x 15 amp CB (not earth leakage, although this decision is up to your discretion).

Notes.

- Main Circuit Breaker should not exceed 80 amps & should not be earth leakage.

- All RCD/CB's & CB's should have a minimum Fault Current Interrupt Capacity of 6kA (6000 amps).

- The M.E.N. system should be employed.

- I suggest the purchase of a minimum 30 pole Main Distribution Board (breaker box).

- I suggest using Square D, Merlin Gerin or Clipsal products.

elk, thanks for this great reply. Could you tell me what this: M.E.N. stands for?

Also, I'm not sure what "30 pole" means. Does this have something to do with the number of slots in the

breaker box for breakers? I'm guessing 15 slots as 30 seems waaaaaay to many.

I read your reply carefully and pretty much know what you've advised; thanks again.

[Crossy]

elk, thanks for this great reply. Could you tell me what this: M.E.N. stands for?

Also, I'm not sure what "30 pole" means. Does this have something to do with the number of slots in the

breaker box for breakers? I'm guessing 15 slots as 30 seems waaaaaay to many.

Elkangorito is always good for accurate information

You need a 30 pole (slot) box because the combined ELCB/MCB units Elk is suggesting for some circuits take two slots each. They offer the advantage of individual ground protection for each circuit, more expensive but less hassle from nuisance trips taking out your freezer whilst you're away for a week.

MEN - is Multiple Earthed Neutral sometimes called PME (Protective Multiple Earthing). It's a standard for new installations in Thailand, your electrician will know (promise). Look for a connection between the ground bar and incoming neutral line.

[LoveDaBlues]

elk, thanks for this great reply. Could you tell me what this: M.E.N. stands for?

Also, I'm not sure what "30 pole" means. Does this have something to do with the number of slots in the

breaker box for breakers? I'm guessing 15 slots as 30 seems waaaaaay to many.

Elkangorito is always good for accurate information

You need a 30 pole (slot) box because the combined ELCB/MCB units Elk is suggesting for some circuits take two slots each. They offer the advantage of individual ground protection for each circuit, more expensive but less hassle from nuisance trips taking out your freezer whilst you're away for a week.

MEN - is Multiple Earthed Neutral sometimes called PME (Protective Multiple Earthing). It's a standard for new installations in Thailand, your electrician will know (promise). Look for a connection between the ground bar and incoming neutral line.

Cossy, thanks for the clarification.

[Gary A]

I just had a look at the electric bill from my friend's villa. 1456 KWH and the amount is 5585.28 baht. Choked me up some.

[elkangorito]

Why should the main breaker be limited to 80 amps....seems to me that bigger would not cause a problem?...would it?...and if so what problem?

Chownah

Since I believe that the KWH meter to be used should be 100 amps & since these KWH meters do not have built-in overcurrent protection, the only thing that will prevent damage to the KWH meter is the MCB (Main Circuit Breaker). The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. In most installations (not in Thailand), the energy authority protects their KWH meter with an HRC fuse, aka the 'consumers fuse' or the 'service fuse'. This fuse is located before the KWH meter & is usually to BS 88 or BS 1361 standard. Its job is to protect the consumers mains from overload & to limit the fault current to the domestic installation. These fuses are normally rated the same (or slightly less) as the current carrying capacity as the consumers mains.

It seems that a 100 amp main circuit breaker would be the right size to protect the KWH meter since they are both 100 amp rated....so I'm still not seeing why you indicated that 80 amps is the max main circuit breaker to be used....what problem does the 100 amp main circuit breaker cause...I still don't get it. In your post you said " The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. "...I can't tell if you are saying that a 100 amp beaker is not good because of the 100 amp meter rating or if you are saying he onliy needs 80 amps so a 100 amp breaker is not necessary. When I got my service (with a 100 amp meter) I was told that a 100 amp main circuit breaker was the largest I should use....and that's what I've got...so I'm trying to anticipate what problem this may cause. The advantage of the 100 amp breaker is more room for future build out compared to an 80 amp breaker.

My main concern is protecting the meter. If the current coils are damaged (due to overload), the meter may read incorrectly or fail, which may lead to bigger power bills. This is an inconvenience either way you look at it.

The accuracy of Thermal Magnetic circuit breakers is affected by ambient temperature. Will the breaker trip at 95 Amps or 105 Amps? I prefer to err on the safe side rather than to gamble on the accuracy of a protective device. Another option is to use a Hydraulic Magnetic CB. They are quite accurate & are not affected by ambient temperature but are difficult to source in Thailand. They are also physically bigger & more expensive than a Thermal Magnetic CB.

Also, this is why an HRC Service fuse is used. It allows you to have whatever size Main Switch you want. It also allows you to choose either an automatic CB or a non-automatic CB as a Main Switch. A non-auto CB is simply a switch & therefore does not have any trip devices within it. This way, if your consumer mains are upgraded as a result of an increased demand, the only thing you'll need to do is change the size of the fuse, which is a very cheap option.

A 100 Amp CB protecting a device rated at 100 Amps offers no margin for error.

I think that from now on, I will be strongly suggesting the use of Service Fuses in all installations. This will solve many problems.

[chownah]

Why should the main breaker be limited to 80 amps....seems to me that bigger would not cause a problem?...would it?...and if so what problem?

Chownah

Since I believe that the KWH meter to be used should be 100 amps & since these KWH meters do not have built-in overcurrent protection, the only thing that will prevent damage to the KWH meter is the MCB (Main Circuit Breaker). The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. In most installations (not in Thailand), the energy authority protects their KWH meter with an HRC fuse, aka the 'consumers fuse' or the 'service fuse'. This fuse is located before the KWH meter & is usually to BS 88 or BS 1361 standard. Its job is to protect the consumers mains from overload & to limit the fault current to the domestic installation. These fuses are normally rated the same (or slightly less) as the current carrying capacity as the consumers mains.

It seems that a 100 amp main circuit breaker would be the right size to protect the KWH meter since they are both 100 amp rated....so I'm still not seeing why you indicated that 80 amps is the max main circuit breaker to be used....what problem does the 100 amp main circuit breaker cause...I still don't get it. In your post you said " The next size CB up from 80 amps is 100 amps, which in not a good selection for this case. His max demand is less than 80 amps. "...I can't tell if you are saying that a 100 amp beaker is not good because of the 100 amp meter rating or if you are saying he onliy needs 80 amps so a 100 amp breaker is not necessary. When I got my service (with a 100 amp meter) I was told that a 100 amp main circuit breaker was the largest I should use....and that's what I've got...so I'm trying to anticipate what problem this may cause. The advantage of the 100 amp breaker is more room for future build out compared to an 80 amp breaker.

My main concern is protecting the meter. If the current coils are damaged (due to overload), the meter may read incorrectly or fail, which may lead to bigger power bills. This is an inconvenience either way you look at it.

The accuracy of Thermal Magnetic circuit breakers is affected by ambient temperature. Will the breaker trip at 95 Amps or 105 Amps? I prefer to err on the safe side rather than to gamble on the accuracy of a protective device. Another option is to use a Hydraulic Magnetic CB. They are quite accurate & are not affected by ambient temperature but are difficult to source in Thailand. They are also physically bigger & more expensive than a Thermal Magnetic CB.

Also, this is why an HRC Service fuse is used. It allows you to have whatever size Main Switch you want. It also allows you to choose either an automatic CB or a non-automatic CB as a Main Switch. A non-auto CB is simply a switch & therefore does not have any trip devices within it. This way, if your consumer mains are upgraded as a result of an increased demand, the only thing you'll need to do is change the size of the fuse, which is a very cheap option.

A 100 Amp CB protecting a device rated at 100 Amps offers no margin for error.

I think that from now on, I will be strongly suggesting the use of Service Fuses in all installations. This will solve many problems.

Thanks for the clarification. I take it that this is your gut feeling and is not based on any codes or manufacturer's specs. Could it be that a 100 Amp meter is rated at 100 Amps meaning that it is compatible with a 100 Amp main breaker?....that seems to be what I was told. This could mean that the meter could actually take more than 100 Amps but its rating contains a safety factor. If you think about it it would not make sense to rate a meter at 100 Amps if that was its "failure" current....it would seem to make sense that there would be some safety factor in the rating. Has it been positively determined yet exactly what the 100 Amp rating means for a kwh meter?