ok..let me ask my electrician..but I belive its 16mm

16mm2 is the standard use right? Now I see many only use 10mm2.

25mm2 will be superb Can take up 80Amps per phase load no problem

Yes. 16mm is actually standard size to be used for 3 phased. if we don't really exceed 60A i don't see the need of 3 phased. can just used single phase with 25mm 2 core to cut cost.

25mm amour cable running underground doesn't cut cost. That cost a lot.

Do you really need 3 phase? single phase (60A incoming) can run 6 X 1.5HP AC (5Ax6) simultaneously with a lot of spares. Last time my house i did rewires for 3 phases ready (originally came with 2 core 16mm and i added another 2 core 25mm from incoming to the db to make it 3 phase ready, but i ended using single phase for nearly 3 yrs now nvr had an issue or tripping. can check what i did at my tread.

Hmm, last time when i did my home the 4 core 16mm price is the same as 25mm two core armored steel. I did mine around 25Meters from incoming to DB Cost less than RM700 if i m not mistaken.

Invest one time can last many years.

hmm donno lar..just thought of getting it done once and for all.

i will be installing

4x1hp
1x1.5hp
1x2.5hp

and 3 water heater

that said not all will run at the same time. maybe max 50% load of the above

you can do like me, get electrician to pull additional 4 core wires for 3 phase ready, not necessary you need to apply with tnb straight for 3 phase. as i say for single phase shall suffice if you are loading 50% as per said items, get TNB to change incoming fuse to 100A, and at the DB you can used 63A units. if you are running 3x1 HP + 2xWH simultaneously will not cause problems, at max you are pulling 12A+30A for those items.

understand what you are doing. but i am also installing the TNB sellback thingy. the seda thing. so i am not sure if it will affect the installation. any idea?

i have no idea about the circuitry of seda/solar, any one doing this can share here as well. can learn

The price the runner will let you know.
Best is get your appointed wireman that have contact to the runner.

If using single phase, got 30mm also I'll get it.
If using 3 phase(provided wiring done right with proper load balancing), then 16mm also will be enough.
Some wireman will still use a single phase even we got a 3 phase supply.
The only advantage on 3 phase wiring is load balancing, so the wires won't be subjected to handle high loads.

Getting Seda? Want to sell back to TNB?
What is the goal you want? If invest to gain money, then you may think again.
I have 2 friends installed this, 1 installed long time ago and his ROI are 7%, another is lower at 3-4%
The rate is getting lower and lower now. So for cooling your house, then go ahead, if trying to make money from it, sorry, wrong tools.
After installing this solar panels(on the right direction to harvest sunlight), you will have a cooler house, your air cond cost also can come down.

why the difference? not enough sunlight? well when i went to it was told coould generate RM600-Rm750 per month so i went in. heard also payment from TNB not regular. anyway the cooling part is an extra for me...

On a 4KW system or higher rated?
The rate are dropping every year.

4kw. yeah rates are dropping with each opening. i got the latest one... RM1.2837/kWh

Now still can get rm600-700? That's the 5-6 years back price
Better check it properly. Still as said before, cooling down your house will bring down your electric bill also.

Due to sunlight being absorb by the solar panel?

Yes, that's right. Or can say you got additional layer of roof.