Hi All,

TNB currently has the 3-phase promotion. Has anyone done it before? I have few questions:

1) It stated there 'overhead line service' and 'underground cable' service. Anyone know what does that mean?
2) My guess is if I don't see 3-phase wires (those 3-colour wires) running across it, then it means only single phase right? Then I will need to do the 'underground cable' service, which only cost rm400 for 60A 3-phase wires. Kinda cheap if it is fixed at rm400 regardless of distance.
3) Does TNB actually has to dig the ground from their main switch over to our house. Does it include digging my car porch?
4) Does the new 3-phase meter come free from TNB with this promotion?
5) I am currently renovating my house, and it has 5 bedrooms. I expect to have my worst case usage of running 5x1hp aircon at night. Do I need 3 phase? How much current does modern air conds consume anyway?
6) If all I need is just rm400, might as well install the 3-phase wire and make my house 3-phase ready even though I might not be changing the DB yet. Is this a correct thinking?

Thanks!

Regards,
Lim

Hi PJusa,

Thanks for the sharing. Based on your experience, seems like I don't need 3 phase though. I checked most aircon branded specs online and they only consume 4-6A (average, not peak), while peak currents can exceed 10A. Peak currents happen when the compressor is starting to run. So using inverter will reduce those peaks and make your current consumption stable like a straight line. If all 7 non-inverter aircons turn on at the same time, the worst case peak current could be 10Ax7 = 70A, which will certainl make the ELCB trip. However, if each aircon is turned on one at a time, then it won't trip.

By the way, what does AAA mean?

Regards,
Lim

Hi Mudtrekker,

I am not an electrician but here's my opinion.

The weakest link of the entire path is the determining factor. Here, your external fuse is 32A, while internal one is 63A, that means your maximum current is still 32A. No point changing just one fuse.

Check your neighbour, what fuse is he using? If your apartment is built with 32A wires, then using 63A fuse has the risk of overloading the wires (might burn).

Fuses are meant to cut your electric supply in the event of overloading. For example, when your heater has short-circuited, huge amount of currents will flow and this will cause the ELCB to trip or the fuse to cut off.

As for #3, no idea about temperature, but as long as the fuse is not cut off, it is ok. Electric current definitely generate heat, and fuses are built to withstand currents up to their maximum.

Having said that, how many electrical appliances are you turning at the same time? 32A is quite a lot for an apartment. Normally air con these days come with just 3-5A rating. So even with 32A, you can run 6 aircons at the same time.

Maybe the fuse is too old and so it burnt and not because of hitting the max 32A? I dunno, maybe you can ask a second opinion from another electrician.

Regards,
Lim

I installed 3 phase because:

1) i have 3 heaters and 8 aircon points (now only install 7).
2) 3-phase installation cost difference is only rm1K+ only (including TNB charges), so just do it and save the headache later.

But generally u don't need 3 phase if only 4-5 aircons+3 heaters, since nowadays aircons use less electricity already. Go for inverter aircons which reduce current spikes and thus will not exceed the 60A maximum rating for 1 phase.