Maximum Demand Calculation For Hua Hin House

[stgrhe]

I and my wife are building a house i Hua Hin and help with a Maximum Demand Calculation would be highly appreciated.

GENERAL

The main meter will be 30/100 and the supply 3 phase. All appliances will be single phase and no plans exist for future 3 phase equipment. The power outlets in the living room area will among others be used for a 50" LED TV, DVD, pre-amplifier, five channel power amplifier (5 x 200W) and an active sub-woofer (1kW). A 1kW movable vacuum cleaner exists too.

LOUNGE / DINING / HALL

18 Down-lights (12W Low Energy)

20 Indirect Lights (18W Fluorescent)

12 Power Outlets (DGPO)

1 Alarm System

3 Ceiling Fans

KITCHEN

4 Down-lights (12W Low Energy)

3 Ceiling Lights (12 W Low Energy)

4 Power Outlets (DGPO) [Toaster & Coffee Machine]

1 Fridge/Freezer (SGPO) 1,430W

1 Hood 290W

1 Hob 6,600W

1 Oven 3,600W

1 Microwave Oven (SGPO) 1,220W

1 Dish Washer (SGPO) 2,300W

1 Water Purifier (SGPO) 100W

MASTER BEDROOM

9 Down-lights (12W Low Energy)

10 Indirect Lights (18W Fluorescent)

8 Power Outlets (DGPO)

1 Ceiling Fan

MASTER BEDROOM - WALK-IN CLOSET

2 Down-lights (12W Low Energy)

1 Power Outlets (DGPO)

MASTER BEDROOM - BATH

2 Down-lights (12W Low Energy)

2 Power Outlets (DGPO)

1 Extraction Fan

OFFICE

10 Down-lights (12W Low Energy)

8 Indirect Lights (18W Fluorescent)

10 Power Outlets (DGPO)

1 Ceiling Fan

INDOOR STORE

2 Down-lights (12W Low Energy)

2 Power Outlets (DGPO)

SECOND BEDROOM

9 Down-lights (12W Low Energy)

8 Indirect Lights (18W Fluorescent)

8 Power Outlets (DGPO)

1 Ceiling Fan

SECOND BEDROOM - WALK-IN CLOSET

1 Down-lights (12W Low Energy)

1 Power Outlets (DGPO)

SECOND BEDROOM - BATH

2 Down-lights (12W Low Energy)

2 Power Outlets (DGPO)

1 Extraction Fan

GUEST TOILETTE / POWDER ROOM

2 Down-lights (12W Low Energy)

2 Power Outlets (DGPO)

1 Extraction Fan

MAIN HOUSE - OUTDOOR

6 Wall-Mounted Lights – Front (12W Low Energy)

4 Wall-Mounted Lights – Terrace (12W Low Energy)

1 Power Outlet (DGPO) – Front

2 Power Outlets (DGPO) – Terrace

4 Pond Lights

1 Pond Pump

AIR CONDITIONING UNITS

1 Air conditioning Lounge/Dining/Hall 52,000 BTU (Inverter)

1 Air conditioning Office 18,000 BTU (Inverter)

1 Air conditioning Master Bedroom 24,000 BTU (Inverter)

1 Air conditioning Second Bedroom 24,000 BTU (Inverter)

WATER BOILERS

1 Main Water Boiler (For Main House's Bathrooms) 150 litres 1,800W

1 Kitchen Water Boiler 30 litres 1,800W

OTHER OUTDOOR APPLIANCES

1 Electrically Operated Main Gate

7 Terrace Floor Lights (12W Low Energy)

3 Terrace Ceiling Fans

2 Swimming Pool Lights

8 Flood Lights engaged by Alarm System (100W)

GUEST HOUSE - INDOOR

8 Down-lights (12W Low Energy)

6 Indirect Lights (18W Fluorescent)

12 Power Outlets (DGPO)

1 Ceiling Fan

GUEST HOUSE - OUTDOOR

1 Wall-Mounted Light

1 Power Outlet (DGPO)

1 Air conditioning Unit 18,000 BTU (Inverter)

1 Water Boiler (30 litres) 1,800W

GUEST HOUSE - BATH

2 Down-lights (12W Low Energy)

2 Power Outlets (DGPO)

1 Extraction Fan

LAUNDRY ROOM

2 Down-lights (12W Low Energy)

2 Power Outlet (DGPO) (excluding WM & Dryer)

1 Washing Machine (SGPO) 2,300W

1 Dryer (SGPO) 2,100W

OUTDOOR STORE ROOM

2 Down-lights (12W Low Energy)

1 Power Outlet (DGPO)

CARPORT

5 Down-lights (12W Low Energy)

1 Power Outlet (DGPO)

PUMP ROOM - INDOOR

1 Fluorescent Light (18W Fluorescent)

1 Power Outlet (DGPO)

1 Main Water Pump 920W

1 Irrigation (Sprinkler) Water Pump 920W

1 Water Filter

POOL EQUIPMENT ROOM - INDOOR

1 Fluorescent Light (18W Fluorescent)

1 Power Outlet (DGPO)

1 Swimming Pool Pump 1,000W

1 Swimming Pool Hydroxinator (MagnaPool Generator) 400W

PUMP ROOMS - OUTDOOR

1 Wall-Mounted Light (12W Low Energy)

1 Power Outlet (DGPO)

[tominchaam]

As you and your wife are building the house what about asking her?

[stgrhe]

As you and your wife are building the house what about asking her?

I suppose the big boys have been bad to you today. Life must be really bad to you poor little man.

[Rimmer]

How can a polite request for a power estimate go off the rails so quickly?

Pay no attention stgrhe I am sure Crossy will be along shortly.

[stgrhe]

How can a polite request for a power estimate go off the rails so quickly?

Pay no attention stgrhe I am sure Crossy will be along shortly.

I really do not Rimmer and as a matter of fact I do not understand some of the blokes here. Thai Visa is a tremendously good forum with so many helpful and knowledgeable members, who sometimes go to extreme to help fellow members. Yet there are others who never contribute anything but only try to be funny on other member's expense. I suppose these guys are in complete disharmony with themselves and have such a strong need to show off so they can forget their miserable lives.

[elkangorito]

Hi stgrhe.

Your MD works out to be about 95 amps, which is close enough to be called 100 amps.

I should have the phase load balance completed by the end of this week.

[stgrhe]

Hi stgrhe.

Your MD works out to be about 95 amps, which is close enough to be called 100 amps.

I should have the phase load balance completed by the end of this week.

Thanks for your help mate. I shall be looking forward to see your recommendations.

[david96]

You should contact the PEA and obtain their conditions of supply and if they can connect a

3 phase supply to your premises and if their distribution transformer can handle the extra load.

http://www.pea.co.th/th/eng/page.php?name=FeeRates

[stgrhe]

You should contact the PEA and obtain their conditions of supply and if they can connect a

3 phase supply to your premises and if their distribution transformer can handle the extra load.

http://www.pea.co.th/th/eng/page.php?name=FeeRates

Thanks for the advice but it is already taken care of by the developer. The three phase line and a new transformer have been ordered and is due to be installed next month.

[stgrhe]

Hi stgrhe.

Your MD works out to be about 95 amps, which is close enough to be called 100 amps.

I should have the phase load balance completed by the end of this week.

Thanks for your help mate. I shall be looking forward to see your recommendations.

I might have forgotten to mention that the circuits will be split types and not with a loop, like they were using for my house in Sydney back in the 80s.

[elkangorito]

A quick question stgrhe...you say "indirect lighting". What does this mean? Is it a light that is plugged into a GPO or something different?

[PeaceBlondie]

Let's give el kangorito a star rating.

[Crossy]

A quick question stgrhe...you say "indirect lighting". What does this mean? Is it a light that is plugged into a GPO or something different?

Elk:-

http://www.schorsch.com/kbase/glossary/i_lighting.html

[stgrhe]

A quick question stgrhe...you say "indirect lighting". What does this mean? Is it a light that is plugged into a GPO or something different?

In some of the rooms the ceilings will be partly risen, squarish kind of boxes if you like, with hidden shelves which will be fitted with fluorescent light tubes. These light sources will give the applicable rooms indirect lights. Hence, some ceilings will fitted with two kinds of light sources of which the down-lights (direct light source) will be the other.

I hope this explains what I mean.

Edited. Sorry, elk, I forgot to answer your question whether these light sources are GPO or not and they are not as they are fixed installations.

Edited November 25, 2009 by stgrhe

[elkangorito]

Thanks stgrhe. I asked because I wasn't sure of what your interpretation of "indirect lighting" was. I have met some people who seem to think it is other than that mentioned in the link Crossy posted e.g. a plug in bedside lamp.

[david96]

Thanks stgrhe. I asked because I wasn't sure of what your interpretation of "indirect lighting" was. I have met some people who seem to think it is other than that mentioned in the link Crossy posted e.g. a plug in bedside lamp.

Also known as pelmet lighting, the light source is not directly visible eg a 1 x36W batten flouor but one can not see the light directly.

[Tracer Round]

"I suppose these guys are in complete disharmony with themselves and have such a strong need to show off so they can forget their miserable lives."

I'm sorry, but this comment really rankles. In every conversation with various people -- be it in a pub or club or online -- you will find those who throw out non sequitors or make off-the-cuff attempts (sometimes successful) at humor (however dry). Maybe he's taking a potshot at you, who knows?

The guy says to ask your wife...and you reply by saying he has a miserable life, has a need to show off and is in complete disharmony with himself (whatever that means, I'm not a psychologist).

Instead of blasting what you perceive as a heckler, you might try to grin and either ignore him, or use your craftiness to reply in such a way as to pass over him without trying to defame him.

Personally, I enjoy these oddball comments; they add spice and don't railroad the threads. Cut these guys some slack.

Conversation in a pub with several people around the bar:

A: "I need to find out the maximum demand for the electric system for the house I am building. Hopefully someone can do the assessment for free. Here is the list of all the lights and aircons and whatnot."

B: "Wow! A pond and a swimming pool and a guest house...what a mansion! That'll be some house. Maybe your wife knows someone locally who can figure out that demand thing for you."

A: "Excuse me, you poor little man. Did I ask for your show-off remarks? If you have nothing to contribute to actually helping me find out the maximum demand for the house then I suggest you take your miserable life and go spread disharmony elsewhere."

[elkangorito]

stgrhe, emails sent regarding Square D catalogs.

Your requirements are a little more than usually required & as such, may take me some time to complete.

For the purposes of updating this thread, your MD calc now stands at about 130 amps. As discussed, this is above & beyond the normal "domestic" limit but by limiting your maximum current, it can be brought down to 100 amps without detrimental effects. If you went ahead with a supply greater than 100 amps, CT's (current transformers) would be needed to "meter" your supply...a more expensive arrangement.

This week, I will identify the cicuit breaker arrangement for your Main Distribution Board (MDB). This will allow me to estimate the size DB (distribution board) you need. Also, the extra equipment you require will need to be in a seperate DB (mounted next to your MDB). Cutouts will be required in this extra DB to accommodate such things as a voltmeter & a selector switch.

I will be quoting Square D products since I have the basic catalog & price list. I propose using single pole RCBO's.

At the moment, it looks like your MDB will be at least 30 poles but I will give you the final result later this week.

[stgrhe]

stgrhe, emails sent regarding Square D catalogs.

Elk, thank you so much for the catalogs.

For the purposes of updating this thread, your MD calc now stands at about 130 amps. As discussed, this is above & beyond the normal "domestic" limit but by limiting your maximum current, it can be brought down to 100 amps without detrimental effects. If you went ahead with a supply greater than 100 amps, CT's (current transformers) would be needed to "meter" your supply...a more expensive arrangement.

I appreciate what you are doing and am very grateful for your advice and support. I do understand the 'dilemma' with regards to the excess current and will thus cancel my first idea of using ABB Tmax circuit breaker with electronic limiting circuit and opt for a less sophisticated solution for the sake of reliability.

This week, I will identify the cicuit breaker arrangement for your Main Distribution Board (MDB). This will allow me to estimate the size DB (distribution board) you need. Also, the extra equipment you require will need to be in a seperate DB (mounted next to your MDB). Cutouts will be required in this extra DB to accommodate such things as a voltmeter & a selector switch.

I shall await your suggestions with great interest.

With regards to the main circuit breaker I wonder whether it is a better idea to keep that unit in a separate box altogether and add HRF's? When looking at the Square D catalog it looks like there is no space for HRF's in their DB's and since the main power line will be under ground in PVC conduits I suppose one should add HRF's as the insulation is probably insufficient compared to Western standards.

I will be quoting Square D products since I have the basic catalog & price list. I propose using single pole RCBO's.

Will a single pole RCBO really be as good as a 1L+N pole RCBO? I taught it would always be a better solution to cut-off both the live and the neutral and not just the live?

[stgrhe]

To reduce the power consumption slightly I have agreed with the builder to delete the dedicated hot water boiler from the kitchen and instead connect the kitchen's hot water to the main hot water boiler. The will delete 1.8 kW from the power consumption.

[Naam]

To reduce the power consumption slightly I have agreed with the builder to delete the dedicated hot water boiler from the kitchen and instead connect the kitchen's hot water to the main hot water boiler. The will delete 1.8 kW from the power consumption.

you are in good hands with ElKangorito BUT i doubt that the 52,000 btu unit is single phase and i strongly doubt that you need a 52k unit. please reconsider, plan smaller units instead, have a better airflow and save energy by using only the capacity you need.

[stgrhe]

you are in good hands with ElKangorito BUT i doubt that the 52,000 btu unit is single phase and i strongly doubt that you need a 52k unit. please reconsider, plan smaller units instead, have a better airflow and save energy by using only the capacity you need.

Yes, he is very good and indeed a true gentleman, I take of my hat and bow.

I know something is not right with the A/C and I have therefore asked another company to estimate the need in the applicable area. The 52,000 BTU figure was actually suggested by an engineer from Siam-Daikin in Bangkok after I had given him all relevant parameters and a layout of the house. Sadly he wouldn't reveal the formula he used. I am not a fully novice in this department but my knowledge is very dated and I simply do not remember how to carry out the calculation properly. My intuition tells me that something around 36,000 BTU or even less is probably more realistic.

I remember though that volume, insulation types (U-values), outdoor temperature and humidity, number of sunny hours per day, window sizes, glass thickness (single / double / triple), direction North / South etc. all matters but not their relation to one another.

[david96]

Schneider Multi 9 C60/120 range. Square D is now Schneider.

Here is their website in Thailand.

http://www.schneider-electric.co.th/sites/...function_id=108

[stgrhe]

Schneider Multi 9 C60/120 range. Square D is now Schneider.

Here is their website in Thailand.

http://www.schneider-electric.co.th/sites/...function_id=108

Thanks David! Elkangorito has promised to chose a suitable circuit breaker for me so I will await his recommendations as there are so variables that I do not fully understand.

[katabeachbum]

Schneider Multi 9 C60/120 range. Square D is now Schneider.

Here is their website in Thailand.

http://www.schneider-electric.co.th/sites/...function_id=108

Thanks David! Elkangorito has promised to chose a suitable circuit breaker for me so I will await his recommendations as there are so variables that I do not fully understand.

samsib/roy in 3 phase/4 wires is an extreme powersupply for a villa, and as listed your peak power will never be close to the limit. But if this is supplied to you, there is no need to choose smaller supply/meter. You could manage with 30/100 in onephase or 15/45 in 3phase/4wires.

For aircons I would choose several smaller units rather than few large ones. Better flow, and still have aircon if one fails for a couple of days.

[stgrhe]

samsib/roy in 3 phase/4 wires is an extreme powersupply for a villa, and as listed your peak power will never be close to the limit. But if this is supplied to you, there is no need to choose smaller supply/meter. You could manage with 30/100 in onephase or 15/45 in 3phase/4wires.

The supply will be 380V 3-phase Y-coupling and the meter rated 30/100 and that is what I have in the contract with the developer. At the moment there is only a smaller single phase transformer but the new one has been ordered from PEA and is expected to be installed within the end of the year.

For aircons I would choose several smaller units rather than few large ones. Better flow, and still have aircon if one fails for a couple of days.

There are a few points with regards the A/C that need be considered. First, the costs for the A/C is not mine as it is part of the developers undertakings and they are limited by number rather than by cost. Hence, should I wish to add more units than what is specified that will be my cost. Secondly, the A/C systems should be inverter multi-flex systems with the indoor units concealed above the ceilings and the outdoor units connected to one or more indoor units depending on the requirement. Also, I have preference for R410A because R22 will be forbidden from year 2015. I do not like the ugly wall-mounted or cassette type units.

At first I was looking at Daikin but I am not too happy with the way they acted and I have therefore also been in touch with Misubishi Electric and they have promised to do a proper calculation for me.

The largest local A/C shop here in Hua Hin do as most Thais are doing, calculating the need by using the floor space only and that would not do.

[katabeachbum]

samsib/roy in 3 phase/4 wires is an extreme powersupply for a villa, and as listed your peak power will never be close to the limit. But if this is supplied to you, there is no need to choose smaller supply/meter. You could manage with 30/100 in onephase or 15/45 in 3phase/4wires.

The supply will be 380V 3-phase Y-coupling and the meter rated 30/100 and that is what I have in the contract with the developer. At the moment there is only a smaller single phase transformer but the new one has been ordered from PEA and is expected to be installed within the end of the year.

For aircons I would choose several smaller units rather than few large ones. Better flow, and still have aircon if one fails for a couple of days.

There are a few points with regards the A/C that need be considered. First, the costs for the A/C is not mine as it is part of the developers undertakings and they are limited by number rather than by cost. Hence, should I wish to add more units than what is specified that will be my cost. Secondly, the A/C systems should be inverter multi-flex systems with the indoor units concealed above the ceilings and the outdoor units connected to one or more indoor units depending on the requirement. Also, I have preference for R410A because R22 will be forbidden from year 2015. I do not like the ugly wall-mounted or cassette type units.

At first I was looking at Daikin but I am not too happy with the way they acted and I have therefore also been in touch with Misubishi Electric and they have promised to do a proper calculation for me.

The largest local A/C shop here in Hua Hin do as most Thais are doing, calculating the need by using the floor space only and that would not do.

yepp, 3phase/4 wires is 380volt in 3phase. 30/100 amp you could run a small hotel.

I m not a fan of aircons concealed in ceiling. Expensive, difficult to service and clean, the smallest leak damage ceiling and often noisy. I do prefer the casette on wall type even if they are ugly.

So far I havent found a decent aircon shop in Hua Hin. Sloppy service. Need 2 more casette type next week, and probably will get them at Home Pro. Is there anyone in Hua Hin who can service R410A?

Mitsubish has a great inverter system with several indoor units on one compressor. Seen it imported from Singapore at a price, but not seen it sold yet in LOS

Edited December 2, 2009 by katabeachbum

[david96]

Schneider Multi 9 C60/120 range. Square D is now Schneider.

Here is their website in Thailand.

http://www.schneider-electric.co.th/sites/...function_id=108

Thanks David! Elkangorito has promised to chose a suitable circuit breaker for me so I will await his recommendations as there are so variables that I do not fully understand.

samsib/roy in 3 phase/4 wires is an extreme powersupply for a villa, and as listed your peak power will never be close to the limit. But if this is supplied to you, there is no need to choose smaller supply/meter. You could manage with 30/100 in onephase or 15/45 in 3phase/4wires.

For aircons I would choose several smaller units rather than few large ones. Better flow, and still have aircon if one fails for a couple of days.

With MD calculations one may regard the actual use of electrical equipment in a single residential electrical installation.

No MD needs to be over 100A for a single phase, 50A per phase for two phase supply ( 2 phases of a 3 phase system + N ) and 32A for a 3 phase supply in a residential environment.

The actual average peak load in amps over any given period will probably not exceed 50% of the MD in practice. Note diversity within an installation.

Airconditioning will certainly increase your load demand, depending on how many aircons one has running at one time. 100% of them or perhaps only 40%( 2 out of five).

One may limit the MD by the installation of a MCB (eg. as the main switch of the installation) but note you may never reach your calculated MD in practice.

To give an example of actual load conditions in practice.

My MD is 40A. Max load in practice would not exceed 16A. Meter 10/60A 16sqmm single phase twin TPS cable, electricity distributors aerial sevice conductors flat twin single insulated pvc 10sqmm and a 100A HRC fuse on the electricity distributors pole.

Load 16 lights and ceiling fans, 15 twin socket outlets,1 HWS off peak 1.8kW, 1 oven and 4 plate cooktop 9.6kW. 1 x airconditioner (5.0A) on one of the power circuits.

MSB consists of 1 x single pole main switch 80A, 1 x 4 pole 40A RCD and 6 x single pole 3kA MCBs.

Note the size of the consumers mains and service fuse. Metering is this case is on the load side of the main switch on the consumers main switchboard.

So if one installed 2 x 15A socket outlets for two airconditioners the max demand would increase by 25A. In this case the consumers mains are unenclosed in air which gives them a rating of 80A for 16sqmm and they have a route length of about 15M

But would one run 2 aircons both at once? Unlikely, just one or the other, and my actual load would rise to about 28A.

This particular installation is in NE Australia, but the same principles apply in Thailand.

And yes smaller aircons, split systems type would give better versatility.

[stgrhe]

With MD calculations one may regard the actual use of electrical equipment in a single residential electrical installation.

No MD needs to be over 100A for a single phase, 50A per phase for two phase supply ( 2 phases of a 3 phase system + N ) and 32A for a 3 phase supply in a residential environment.

The actual average peak load in amps over any given period will probably not exceed 50% of the MD in practice. Note diversity within an installation.

Airconditioning will certainly increase your load demand, depending on how many aircons one has running at one time. 100% of them or perhaps only 40%( 2 out of five).

One may limit the MD by the installation of a MCB (eg. as the main switch of the installation) but note you may never reach your calculated MD in practice.

To give an example of actual load conditions in practice.

My MD is 40A. Max load in practice would not exceed 16A. Meter 10/60A 16sqmm single phase twin TPS cable, electricity distributors aerial sevice conductors flat twin single insulated pvc 10sqmm and a 100A HRC fuse on the electricity distributors pole.

Load 16 lights and ceiling fans, 15 twin socket outlets,1 HWS off peak 1.8kW, 1 oven and 4 plate cooktop 9.6kW. 1 x airconditioner (5.0A) on one of the power circuits.

MSB consists of 1 x single pole main switch 80A, 1 x 4 pole 40A RCD and 6 x single pole 3kA MCBs.

Note the size of the consumers mains and service fuse. Metering is this case is on the load side of the main switch on the consumers main switchboard.

So if one installed 2 x 15A socket outlets for two airconditioners the max demand would increase by 25A. In this case the consumers mains are unenclosed in air which gives them a rating of 80A for 16sqmm and they have a route length of about 15M

But would one run 2 aircons both at once? Unlikely, just one or the other, and my actual load would rise to about 28A.

This particular installation is in NE Australia, but the same principles apply in Thailand.

And yes smaller aircons, split systems type would give better versatility.

Thanks for your comments David. All professional advice are most welcome and highly appreciated.

With regards to the matter of MD calculations I assume one can do that using two different methods; one, using the max rated power for all equipment installed and assuming they are all running at full blast and using a percentage, e.g. 50%, of that max load; or two, using a formula depending on the numbers and type of units connected. The latter is what Elgangorito is using and he has kindly promised to do the calculations for me using, what I believe, an Australian rule of thumb.

Before proceeding I shall thus wait for Elkangorito's recommendations.

[david96]

With MD calculations one may regard the actual use of electrical equipment in a single residential electrical installation.

No MD needs to be over 100A for a single phase, 50A per phase for two phase supply ( 2 phases of a 3 phase system + N ) and 32A for a 3 phase supply in a residential environment.

The actual average peak load in amps over any given period will probably not exceed 50% of the MD in practice. Note diversity within an installation.

Airconditioning will certainly increase your load demand, depending on how many aircons one has running at one time. 100% of them or perhaps only 40%( 2 out of five).

One may limit the MD by the installation of a MCB (eg. as the main switch of the installation) but note you may never reach your calculated MD in practice.

To give an example of actual load conditions in practice.

My MD is 40A. Max load in practice would not exceed 16A. Meter 10/60A 16sqmm single phase twin TPS cable, electricity distributors aerial sevice conductors flat twin single insulated pvc 10sqmm and a 100A HRC fuse on the electricity distributors pole.

Load 16 lights and ceiling fans, 15 twin socket outlets,1 HWS off peak 1.8kW, 1 oven and 4 plate cooktop 9.6kW. 1 x airconditioner (5.0A) on one of the power circuits.

MSB consists of 1 x single pole main switch 80A, 1 x 4 pole 40A RCD and 6 x single pole 3kA MCBs.

Note the size of the consumers mains and service fuse. Metering is this case is on the load side of the main switch on the consumers main switchboard.

So if one installed 2 x 15A socket outlets for two airconditioners the max demand would increase by 25A. In this case the consumers mains are unenclosed in air which gives them a rating of 80A for 16sqmm and they have a route length of about 15M

But would one run 2 aircons both at once? Unlikely, just one or the other, and my actual load would rise to about 28A.

This particular installation is in NE Australia, but the same principles apply in Thailand.

And yes smaller aircons, split systems type would give better versatility.

Thanks for your comments David. All professional advice are most welcome and highly appreciated.

With regards to the matter of MD calculations I assume one can do that using two different methods; one, using the max rated power for all equipment installed and assuming they are all running at full blast and using a percentage, e.g. 50%, of that max load; or two, using a formula depending on the numbers and type of units connected. The latter is what Elgangorito is using and he has kindly promised to do the calculations for me using, what I believe, an Australian rule of thumb.

Before proceeding I shall thus wait for Elkangorito's recommendations.

I use the same formula as in AS3000/2007 for calculating max demand. Due to diversity in an electrical installation

the average peak load is far lower because one is not using all his connected load at once. The Max demand does not change only your actual peak load. In Australia one always tries to keep the max demand down to a minimum

that will still comply with AS3000 and with the electricity distributors own requirements. Max demand determines your size of consumers mains.