Electrical for a brand new house build - questions

[Petey303]

I am working on my electrical connection for my house build. What I have gathered from reading around the forum:

• Electric connection - 30/100 amp 3 phase
• Must be grounded

 

I want to have a power plan including Generator and UPS for outages. I know they don't happen much, but I want to ability to run part of the house. So I want to wire the house to be able to have a UPS cut in and just power the electronics, lights, and refrigerators/freezer (maybe pick one or two outlets that stay on).

 

How do I specify this in the drawings? 

What are the common Thai pitfalls I should be aware of?

 

Thanks for any help!

 

[KhunKenAP]

Don't forget solar panels and wind if you have the space.

 

Biggest problem will be find a qualified electrician. Ask them what the ground does and how they would hook it up. If they can't answer, move on.

[Crossy]

How big is your home? Have you done a prospective load estimate? (do you need such a big supply?)

 

If you are outside the major conurbations you are not going to get a 30/100 3-phase without paying $$$ for your own transformer.

 

Task A. Would be a block-diagram of what you want to do.

 

You would have three supplies:- 

• Vital (supplied by your UPS or hybrid solar)
• Essential (from your genset)
• Domestic (goes off with the mains) 

Then define what you want on each supply (e.g. water heaters would be "Domestic").

 

That will allow you to size the genset and UPS.

 

[Petey303]

The house is 360 m2.

 

I like the three zones, I will specify that for the builder. 

 

What do they use to switch over from UPS/Generator? I want the house to run on mains all the time. I "switch in" the UPS or Generator when there is a problem. I did not want to have a UPS in pass through powering the house all the time. And I may only have a generator (no big UPS) and use a small UPS internal on the critical electronics (Internet/WiFi/Cameras).

 

[sometimewoodworker]

2 hours ago, Petey303 said:

The house is 360 m2.

 

I like the three zones, I will specify that for the builder. 

You can have as many zones as you like. The size of the house says little about the electrical equipment you will want. 3 phase can be good or totally over the top depending on what you want to power.

it may not even be an option.

[bankruatsteve]

3 hours ago, Petey303 said:

And I may only have a generator (no big UPS) and use a small UPS internal on the critical electronics (Internet/WiFi/Cameras).

That would be best IMO.  You will need a load estimate to properly size the generator.  3-phase is problematic for genset switch-over.  Unless you have a LOT of aircons and 2-3 swimming pools, it's really not likely you will need 100 amp 3-phase.  Again, you really need to estimate what kind of equipment you will need to power with long term possibility before locking in on phase requirement.  As mentioned you could have a CU per as many zones as you like and still use single phase entrance.

[thaibeachlovers]

While it's not exactly what you wanted to know, take the number of power outlets you plan for and double the number. Most of us never have enough power outlets once we buy all the electrical junk toys we want.

[jojothai]

8 minutes ago, bankruatsteve said:

 it's really not likely you will need 100 amp 3-phase. ..

.

  As mentioned you could have a CU per as many zones as you like and still use single phase entrance.

Yes, why would 3 phase be necessary, it brings you other potential problems of having the three separate supply zones.

If i am interpreting what crossy said was suggesting is three different types of supply categories that i presume could be in each zone.

If so, i think you need to be careful working out how many boards and circuits you will need for safety if using 3 phase. 

Somebody else may understand this better to add comment.

[jojothai]

When i built my new house in the sticks, i reckoned that i may need up to 100 amp later. If so i would have to get my own transformer and may have had to use 3 phase.

I designed the circuits for 3 phase zones to be available if necessary, But connected existing supply single phase 15/45.

This has not been a problem, power usage has not been as much as expected, so i have not needed to upgrade.

Mind you i only have about 120m2 floor area, 2 big bedrooms and 2 smaller bedrooms. You have much more. I find we dont have to use much aircon. Your house design influences that.

Edited August 20, 2020 by jojothai
Add detail

[Crossy]

@Petey303 do you have an outline floor plan you can share? We can then do a quick and dirty prospective load calculation. 

 

I suspect you're going to be looking at a 15/45 3-phase supply which should mean you won't need your own transformer.

 

I agree with the idea of individual small UPS's for critical stuff (that's what we are doing) and 3-phase 10 kVA diesel "silent" genset with a fully automatic transfer switch / starter. Even if you don't get the genset immediately arranging for the transfer switch and wiring is much easier from new rather than retro-fitting later.

 

Our home is 360m² but most of the space is naturally ventilated, our aircon is a total of 54,000 BTU but only about 50% of that is ever running together. We manage on a 15/45 single-phase supply, 50A incoming breaker has never opened on overload although my power-logger says it's come close.

 

We also have 5.8kW of grid-tie solar on the car-port which provides about 50% of our energy usage.

 

EDIT The killer consumers are on-demand water heaters (6kW is about 27A), if you go for storage (tank) type heaters you will be able to get away with a much smaller supply. Solar water heating is of course excellent. Gas heaters are also a good option.

[sometimewoodworker]

2 hours ago, thaibeachlovers said:

While it's not exactly what you wanted to know, take the number of power outlets you plan for and double the number. Most of us never have enough power outlets once we buy all the electrical junk toys we want.

Like this? ???? 

Edited August 20, 2020 by sometimewoodworker

[Petey303]

19 hours ago, Crossy said:

do you have an outline floor plan you can share? We can then do a quick and dirty prospective load calculation. 

Attached

 

19 hours ago, Crossy said:

I agree with the idea of individual small UPS's for critical stuff (that's what we are doing) and 3-phase 10 kVA diesel "silent" genset with a fully automatic transfer switch / starter. Even if you don't get the genset immediately arranging for the transfer switch and wiring is much easier from new rather than retro-fitting later.

Yes, this is what I want to do.

 

19 hours ago, Crossy said:

We also have 5.8kW of grid-tie solar on the car-port which provides about 50% of our energy usage.

 

Yes, interested in putting solar in as well.

 

19 hours ago, Crossy said:

The killer consumers are on-demand water heaters (6kW is about 27A), if you go for storage (tank) type heaters you will be able to get away with a much smaller supply. Solar water heating is of course excellent. Gas heaters are also a good option.

We are doing an electric heater tank in the attic for the whole house.

 

Question for you Crossy - do you have central AC? I am going with inverter room style AC units. Seemed like a good choice since the house is giant and may not be fully populated at times. Why did you go central air? And does that mean you have ducts?

 

FloorPlanForHouse_20200816.pdf

[Crossy]

1 minute ago, Petey303 said:

Question for you Crossy - do you have central AC? I am going with inverter room style AC units. Seemed like a good choice since the house is giant and may not be fully populated at times. Why did you go central air? And does that mean you have ducts?

 

We have individual split units like pretty well everyone. Our home design doesn't lend itself to central anyway.

 

I'll peruse your layouts once I escape from the office, the Boss called a meeting on a Friday afternoon, again ????

 

 

 

 

[Crossy]

36 minutes ago, Petey303 said:

I am going with inverter room style AC units.

 

Have you sized your aircon units? If you tell us what you intend having I can check the power consumption.

[Crossy]

Sorry, another question or two:-

• Cooking electric or gas? Giant US style range or something simpler?
• Pool?
• Man-cave with power tools?
• Well pump?

[Crossy]

OK a quick and dirty load assessment:-

 

Downstairs

2x24000 BTU A/C + 1x9000 BTU => 5,700W => 26A

Upstairs

3x9000 BTU A/C + 1x12000 BTU = 3,900W => 18A

 

Water heater (big tank) = 6,000W => 27A

 

General lighting (LED) 500W => 3A

General Power 2500W => 11A

 

Total assuming upstairs and downstairs A/C is not running together would give a peak of 30A per phase. Easily within the capabiltiy of a 15/45 3-phase.

 

In reality you probably won't get anywhere near that. So an electric cooktop and oven would be OK too.

 

[Petey303]

16 hours ago, Crossy said:

 

Have you sized your aircon units? If you tell us what you intend having I can check the power consumption.

I have not yet. I do not know what is involved, is this something the builder prepares, or do I do this?

 

[Petey303]

16 hours ago, Crossy said:

Sorry, another question or two:-

• Cooking electric or gas? Giant US style range or something simpler?
• Pool?
• Man-cave with power tools?
• Well pump?

Electric Range in the inside kitchen, Gas outside

No Pool, but would like the option one day

Yes, man cave with power tools (see the room behind the garage)

No well pump

[Crossy]

1 minute ago, Petey303 said:

I have not yet. I do not know what is involved, is this something the builder prepares, or do I do this?

 

Your aircon installer would be able to size the units for you.

 

The easy guesstimate solution used by most installers here is 600-700 BTU per m² of room floor area, that's what I used in my load calculation in post 16.

[Petey303]

12 hours ago, Crossy said:

OK a quick and dirty load assessment:-

 

Downstairs

2x24000 BTU A/C + 1x9000 BTU => 5,700W => 26A

Upstairs

3x9000 BTU A/C + 1x12000 BTU = 3,900W => 18A

 

Water heater (big tank) = 6,000W => 27A

 

General lighting (LED) 500W => 3A

General Power 2500W => 11A

 

Total assuming upstairs and downstairs A/C is not running together would give a peak of 30A per phase. Easily within the capabiltiy of a 15/45 3-phase.

 

In reality you probably won't get anywhere near that. So an electric cooktop and oven would be OK too.

 

Thanks Crossy. So if I started with 15/45 3-phase, could I move to 30/100 later? Sounds like that may be an option, wanted to clarify. 

 

Thanks again for all the help! Would love to show you the house sometime when we are done ????

[Crossy]

Just now, Petey303 said:

Thanks Crossy. So if I started with 15/45 3-phase, could I move to 30/100 later? Sounds like that may be an option, wanted to clarify. 

Thanks again for all the help! Would love to show you the house sometime when we are done ????

 

Make sure your sparks sizes the wiring from the street to your home for a 100A supply then if you need to you can upgrade the meter without loads of messing around.

 

Why not start a thread in the housing forum with you construction progress, photos, disasters?

 

[Petey303]

1 minute ago, Crossy said:

Why not start a thread in the housing forum with you construction progress, photos, disasters?

 

I already have one going, I am on installment 5 already ????  ????

 

[crazykopite]

That’s going to Cost you a lot of money maybe you should look at the cost of Solar and use low voltage lighting and inverter air conditioning / refrigeration if you go down this road you don’t have to worry about electricity costs or outages or no electric if PEA decide to switch the electric off from 8 till 5 . Solar power had decreased over the last few years . If you want to save on costs ship your items direct from China this is what I did my swimming pool lights were 60% cheaper than what I would pay in Thailand and touch wood 3 years on everything I shipped LV lighting , sockets , switches are all in good working order . Took 4/5 weeks to arrive but I was in no hurry as the electrics were at least two months from fitting and dont forget earthing of the set up

As an after thought do you really want to listen to a geny running why not use a couple of solar panels as an alternative 

Edited August 22, 2020 by crazykopite

[thaibeachlovers]

On 8/20/2020 at 11:10 PM, sometimewoodworker said:

Like this? ???? 

That's getting near the requirement, but could still do with a few more :-).

I prefer mine higher than the common height, which I can do as I do my own electrical work. Would be good in any Thai house likely to be flooded.

[rumak]

On 8/20/2020 at 11:46 AM, Petey303 said:

The house is 360 m2.

 

I like the three zones, I will specify that for the builder. 

 

What do they use to switch over from UPS/Generator? I want the house to run on mains all the time. I "switch in" the UPS or Generator when there is a problem. I did not want to have a UPS in pass through powering the house all the time. And I may only have a generator (no big UPS) and use a small UPS internal on the critical electronics (Internet/WiFi/Cameras).

 

My humble abode is about 100 m2 .      I guess you have a big family

[BritManToo]

On 8/20/2020 at 11:46 AM, Petey303 said:

The house is 360 m2.

 

I like the three zones, I will specify that for the builder. 

 

What do they use to switch over from UPS/Generator? I want the house to run on mains all the time. I "switch in" the UPS or Generator when there is a problem. I did not want to have a UPS in pass through powering the house all the time. And I may only have a generator (no big UPS) and use a small UPS internal on the critical electronics (Internet/WiFi/Cameras).

 

UPS switches itself in when the mains power goes off.

You can take your time switching from mains to generator while the UPS is working.

 

Happy with mine, powers my entertainment (computer, Xbox, NAS, router, fan, 65" tv) for 3-4 hours with a 100ah battery, can add more batteries for a longer backup time but at 5k a pop not really worthwhile. Some day I'll get around to mounting it in a rainproof box on the outside of the house.

 

Edited August 22, 2020 by BritManToo

[bluejets]

17 hours ago, Crossy said:

OK a quick and dirty load assessment:-

 

Downstairs

2x24000 BTU A/C + 1x9000 BTU => 5,700W => 26A

Upstairs

3x9000 BTU A/C + 1x12000 BTU = 3,900W => 18A

 

Water heater (big tank) = 6,000W => 27A

 

General lighting (LED) 500W => 3A

General Power 2500W => 11A

 

Total assuming upstairs and downstairs A/C is not running together would give a peak of 30A per phase. Easily within the capabiltiy of a 15/45 3-phase.

 

In reality you probably won't get anywhere near that. So an electric cooktop and oven would be OK too.

 

Crossy, 

Don't think there was mention of how far this bloke has to run his mains or how far he is from the nearest transformer.

           

[DUNROAMIN]

3 Phase, Overkill. Man what are you planning for, a factory out the back with heavy machinery. Single phase 60 amp, 2400W generator will almost run the whole house as back up. Install a change over switch from mains to Auxiliary. Install good quality RCBO circuit breaker hub and group your breakers per the load in each area of the house.

[Crossy]

10 minutes ago, DUNROAMIN said:

3 Phase, Overkill. Man what are you planning for, a factory out the back with heavy machinery. Single phase 60 amp, 2400W generator will almost run the whole house as back up. Install a change over switch from mains to Auxiliary. Install good quality RCBO circuit breaker hub and group your breakers per the load in each area of the house.

 

Have you checked out his floor plans? There's >96,000 BTUs worth of airconditioned space.

 

He MAY be able to get a single-phase 30-100 meter, which would support the calculated load (but probably not his electic range), depending upon where he is, but a 15-45 single-phase won't support his prospective load.

 

A 15-45 3-phase really is going to be his best bet.

[AlfHuy]

On 8/20/2020 at 6:10 PM, sometimewoodworker said:

Like this? ???? 

there is even one to pluck in your future Mercedes electric car.