If you have more than 1 water heater, and use it concurrent when all the 3 a/c is switch on you maybe hitting > 10K Watt. That will be better to use 3 Phase.

If you know know the max watt draw is < 10 K watt, you don't really need 3 phase.

Happen in my mother house once,

2 Instant water heater switch on, 3 A/C switch on, + TV + 2 fridge + other items. DB box fuse blow. Got to temporary "Kung Fu" the fuse to use while i go out buy replacement. My mom house using old school DB box all fused, no reset-able MCB.

Newer house should be able to reset.

But for my new house, will have to be careful, cause I run two independent DB Box.

Worry your pocket. TNB will be happy too.

Change 3 phase not only just do the DB box. Unless you already pre plan and have your DB box wire for future 3 Phase.

Inside your DB box, if only got 15 MCB, how you want to distribute the incoming 3 hot wires? (RYB)

Than If TNB don't allow house owner to put meter inside the house, house owner need to hack and put outside, beside the gate pillar. More work.

Actually come to think about it, i got more direct power socket than 3 phases house. I got total of 30+ socket, and 80% of it are direct to fuse box.

I got 2 DB box

Post #348
http://forum.lowyat.net/topic/1920588/+340

Got, 3HP and above A/C, and heavy duty Oven.