What?

I think you looking into burning your house.

Like i comment before, changing fuse is simple, can even put in 200Amp if there is one available, but can your wire handle the load?

One heater Max load is 15Amps, you switch on 15amps x 3 = 45amps,

1HP ~ 4Amps, 3.5hp = 14 Amps

You do the math

This post has been edited by weikee: Dec 20 2016, 03:19 PM

so bro, what's your recommendation for my house situation?

Option 1:
Ask wireman check the thickness of wires used, and use the correct recommended fused for the thickness wires you have.

Option 2:
Change the the wires that support 100Amps as you use 100Amps fuse.

What you earlier did was having a car that can run 100MPH, but the road was earlier tested on 40MPH. You either change the car to suite the road, or change the road to suite the car. Is your option.

Kawan, when mention "wireman to check the wires thickness", the qualified wireman will know what to do lah. Not checking the wire insulator thickness.

actually not an expert in electrical, so correct me if i am wrong...actually if i change the cutoff fuse to 100A, RSD to 100A and DP Insulator to 100A, isit it means that i change this for the purpose if on the same times if i use my electrical appliance, total combines can tahan until 100A. why actually still need to check the wire. each individual wire already protected by MCB (20A) where each individual wire cannot exceed 20A, if exceed will cause trip in MCB. actually i did plan upgrade for 1 MCB to maybe 40A (coz my water heater and aircon sharing wire by looling). only need to check this wire whether can tahan 40A or not rite?


or actually bro here mean need to check cable from tnb box to DB box only bcoz maybe the wire from tnb meter to DB box last time not support for 100A electricity? not the whole house wiring rite?

and one more things, i check thru internet, actually single phase max can support until 100A based on internatioanl standard. isit because of TNB we only can be max 63A?


sorry if my question look dumb coz i am not expert in electical, so hope all sifu here can enlighten me.

actually already pay deposit to that electrician (told me need it to buy electical part) and he will come to install it on saturday, if really got problem, i think i need to consult another electrician. actually i already call them to issue my worry, he just say no problem one and my wiring can support blah blah....not an expert in electical, so not argue with him a lot coz that electrician a little cocky one.....


thanks....

This post has been edited by cyberkoh88: Dec 22 2016, 07:10 PM

You're right..

A HRC fuse protects the immediate wiring subcircuit..

Based on this logic..

100A single phase requires wire size to be 2x25mm2 copper cable or bigger for Live & Neutral .. means from 100A HRC fuse to TNB Kwh meter to 100A Distribution Board (DB)..

So this means your inside your DB must have a 100A Double pole (DP) to 100A RCD (to outgoing SP mcb Live busbar and to Neutral Bar) all still using 25mm2 wire ..

The only problem to this is the normal wire size that can fit inside a residential DB is only 10mm2.. which is only rated to 40A

If you know what your wireman is doing and he is indeed replacing the wire it is all good..

I am saying it is very hard and almost impossible to fit a 25mm2 pvc copper wire within a residential DB and I think your wireman is taking you for a fool..

Another thing is the combined (maximum demand) load which can trip a 40A mcb will not blow a 100A HRC fuse..

What usually happens if a fault happens is a high fault inrush current(usually from AC motors) will melt fuse the 40A mcb contacts making it unable to trip heat up the 10mm2 copper cable and start to burn ..

This fault current will not trip a 100A HRC fuse (which is a slow thermal response high rupturing capacity type and not a magnetic type tripping device)..

A fuse blows open and mcb (miniature circuit breaker) magnetically trips (and a bimetallic thermal trip but the primary trip function is magnetic)..

The decision is yours to make but if you do it wrong it is a safety issue ..

Edit * If you refer to the Suruhanjaya Tenaga tables for current carrying capacity the minimum cable size for 100A (enclosed in conduit) is 35mm2..

You must tighten the cables to make good contact if you know you have high loads or the connection points will heat up, start to arc and loosen in time..

This post has been edited by Richard: Dec 23 2016, 12:41 AM

Any qualified wireman will always check the correct wires to the fused, it can have thick wires (thick cores for the nit picking) lower rated fused, but not vice-versa.

<layman>
In any house, there are basic 3 protection, TNB Wires to Meter will have the incoming fuse, from Meter to DB box to distribution will have Main fuse and ELCB/RCD, than MCBs for individual circuit. All combined current will sum into ELCB and Main fused, than flow to the incoming fuse.

So few things to check
- Is the wires to the meter able handle 100Amps?
- Is the meter able to handle 100Amps?
- Is the Live and Neutral wires from Meter to DB Box able to handle 100Amps?
- Is the DB Box busbar able to handle 100Amps?

So if all the 4 able not able to handle 100Amps, there is 4 possibility of location to start a BBQ.

100A needs to have the correct current carrying capacity cable size..

If you go by Suruhanjaya Tenaga guidelines installation in conduit, it is 2x35mm2 copper conductor for live and neutral..

The problem is the standard cable size at the cutout fuse and Neutral link is 2x25mm2 or 2x16mm2 which means you can only put in a 60A/40A rated fuse..

If you want 100A single phase you need to pull a new 2x35mm2 copper cable from the mains to the cutout fuse , neutral link, kWH meter and DB to fully comply to ST guidelines..

Which is why it is normal practice to bring in another phase wire (25/16 mm2 copper) to cater for the additional load..

ok?

This post has been edited by Richard: Dec 23 2016, 10:42 AM

You must have been dropped on your head as a baby or your parents are siblings..

Can you read what I typed?

Edit * Is there some sort of brain drain going on in the west? Why is it this guy still commenting on posts he obviously cannot understand..

This post has been edited by Richard: Dec 23 2016, 10:49 AM

Hi.

I would like to ask. Based on today's standard. How much is the average cost to change from single phase to 3 phases?

I'm planning for my house renovation. We planned to rewired the entire house power cable anyway.

After consult with all sifu here,decided to change cutout fuse to 63A, RCD change to 63A to match My current DP insulator 63A, MCB decided not to upgrade to bigger amp,decided to rewiring my aircon point to nearest power socket (looping) instead of sharing with current water heater point. Thanks for all the sifu advise here,appreciated.

This post has been edited by cyberkoh88: Dec 24 2016, 09:44 AM

Cannot just upgrade MCB to bigger amp, that also looking for worse trouble. Normal house wiring is 2.5mm2 for a/c or water heater, and usually it will use MCB 20amps as cut off, if you increase to anything larger the wire will burned before even the fuse blow.

Have you confirm the nearest socket are not use for other things? It could be shared by another room. Best is trip the MCB for the socket and test what else are affected.

If rewiring, put a 4mm wire. Anything you want to rewiring.

It is for your future expansion and saving.

Hehe, like my house after renovating, the most things I have is independent socket. All with individual mcb, and independent db box breaker for ground and first floor.

When have a chance to upgrade, why not make some different.

Not cost that must. But have more benifit.

Hi,

looking to buy 25mm 4 core sva (armoured cable) (mega cabel recommend by fren)...looking to build 2nd db at the back of house.

can recommend seller around Shah Alam / Subang / PJ area?

Thank you

This post has been edited by billyboy: Feb 22 2017, 09:20 AM

Google up electrical shops and your area name..

Ask for 4core/25mm2 (cross sectional area of the cu conductor) swa (steel wire armoured) underground cable..

If you're buying the material for your wireman you will need the correct size cable lugs, cable gland and some pvc wire tape so make sure to get those at the same time..

appreciate it Richard.

getting quotes of about RM35 to RM50 / m for the 25mm 4c SVA....not cheap....but for peace of mind [note: subang house burnt down a few weeks ago suspect due to electrical issues] and since i don't intend to move house....

noted on cable lugs and glands too...will need to learn....thanks for point the right direction...

Hello, my house have 6 AC (1 x 1.5hp, 3 x 1hp, 2 x 2hp) and 4 water heater with pump. Normally it is max to 4 AC open in sleep time. Am I need to change from single phase to 3 phases?