at my old house, all single phase. Every few weeks electricity will down coz there are 2 houses belonging to a big family...i think like 3-4 brother sister and their families staying together. One day TNB guy come when no electricity...he was very angry and want to see our meter. I pointed him down the road

Actually the question of 3 phase or single phase is really up to the amount of current (Amps) drawn.

3 Phase is a power distribution method to save cost on power lines and distribution copper cables. So for industrial and high power usage businesses like restaurants, etc, 3 phase is most efficient and cheaper to implement than single phase for the same Amps or current draw.

Each incoming is usually still 60A but at 120degree phase apart. At the DB board inside the house, the 3 phase incoming is distributed to all the different circuits to balance the load as best as possible. All equipment in our homes are single phase. Even water pumps in our homes are single phase since the power is abt 1HP.

Actually 60A single phase is quite alot of power for a house. This is steady load. Usually it is hard to exceed this unless there is many aircons, water heaters and pumps.

The big energy devices generally in increasing order: water pump, aircon compressors (1-2HP), water tank heaters (50l above), ovens. Instant heaters and small tank heaters are not really big power consumers.

Invertor aircons do help in smoothening the power draw when starting up and when used in multi room systems. Otherwise, if they are full on all the time, power load is the same as full on non-invertor aircon.

Here is some info:

http://en.wikipedia.org/wiki/3_phase_power
http://www.allaboutcircuits.com/vol_2/chpt_10/2.html

Cheers!

great info

That is why know your house usage, max concurrent drawn will be best. Not always renovation must change to 3 phase.

It depends on Amp drawn.
Not about few electrical items.

A single phase can load up about 50-60A.

So you can count the electrical item need for the Amp.

A water heater (depends on type installed), can draw 1000-3000W, which translate about (if use 3000W) 3000/240v = 12.5A
So for 2 3000W water heater can consume 25A already.

1HP = 0.75KW , which require at least 3.125A.
For 5 x 1Hp require about 16A already.

If using 1.5Hp x 5 = 23.44A,

Both added together 1.5Hp + 3 x 3000KW and if using simultaneously means about 50A, not yet counting refrigerator, washing machine, and others.

Water heater/heating element, and those appliance with motor, generally are the major consumption of the electricity, so people generally target on those to count.
Lighting like a 36W light tube consume 36/240v = 0.15A only, so again can count how many Amp needed.

Can always count on your own. Very simple calculation only.

Generally if the house needs more than 50A, generally advisable got for 3 phase.

3 phase incoming doesn't mean we use 3 phase, all out household/socket is using single phase only, just you draw the current from different phase.
Just like A aircond using one phase, while B water heater using another phase, while socket using another phase.

This post has been edited by cherroy: Nov 4 2012, 06:14 PM

I heard if change from single phase->3-phase need RM2-3K for TNB. is that true?

I hav this plan also single to 3 phase wiring

I check with my contractor,
if the use max 5 aircon, don't need to switch to 3 phase, as long as those aircon not ON at the same time.
Means you can switch on living room aircon first then go upstair switch on the rest of aircon one by one, then is OK.

This post has been edited by sovietmah: Nov 16 2012, 09:44 AM

i have around 8 HP total A/C on single phase on at the same time. no problem at all - but i use inverter A/C.

it's not the quantity but the total peak load. all the other statements are blanket statements and dont give you a real insight. they are "guesstimates".

OK noted.
then I dont want waste too much money to change to 3-phase.

its probably best you check what appliances you intend to use and how. then you can assess your maximum load and choose accordingly. with today's electrical appliances you use much less power in total and more importantly peak loads are lower (remember the old aircons with a seperate starter point, the start-up load was too high so they couldnt be used with a normal 13 Amp plug, now even a 2 HP inverter doesnt have a problem with a 13 Amp plug). I think the wisdom 4 (or whatever) aircons or more = 3 phase wiring comes from the old old high start up loads.

i can even run all a/cs, my fridges, pcs, etc. and on my oven to bake a cake and 1 phase is still fine.

True true.
the electric appliance condition also affect the situation.
I planned to install 5 inverter aircon, 3 heater, 1 fridge and usual power socket.

the heaters might be an issue. what heaters precisely? i have "traded-in" the good old electric heaters with a whole house gas-water-heater from rinnai.

some of the heaters suck over 3000 W and they have huge peak loads.

I checked with my contractor(very very close friend with me) he die die also don't wan to help me to convert 3phase. 3 persons only staying in a hse, why waste $$. But I was thinking, to add fuse box & standby for future use.

Why you want to waste the money to convert something that not neccessary?

Don't be so good lah to TNB.

Same situation, I want to pay my contractor to change to 3-phase, then my contractor keep stop me.

Look like me not going to invest on 3-phase

worst comes to worst move to factory building...definitely 3 phase

Why need 3p? running concurrent 3 water heater + 3 a/c + fridge? or have 300 units of lights lighting everyday?

I don't understand why people keep on thinking want to pay more for the bill. Are they really rich to think use as much electricity as possible?

If my bill over rm100, Gigi sudah sakit.