This is how to read them

https://www.electricaltechnology.org/2015/0...ata-rating.html

The number you see is the reading. The C in front like C20 is the type (characteristic behavior of the MCB), 20 means 20A. The 6A is for lighting and fans. The 20 one is for 3-pin socket. You can see more on how the recommended rating for different purpose in the Guideline link I provided.

So mcb uses 32a but fuse 35a?

What you mean? Illogical to put 60A fuse on the 32A main CB, right? Your main CB is only 32A?

The CM rating is the same as fuse, normally.

This is the main switch?
Pls take clear pic of whole DB box and the two largest blocks in there for better commentary.

And use the clamp meter to check the outgoing current.

attached, thanks all!


Attached thumbnail(s)

Your MCB is at third row next to RCCB and it is 63A.

Is it single storey house with one DB?

Did the power cut happen when you turn on any house appliance?

This post has been edited by juzmafia: Feb 15 2022, 02:39 PM

thanks for reply..
it is single storey built since 2015, while stayed since 2017..
only one db box here..
i only suspected due to turned on heavy load appliances at same time, as mentioned:
- dryer
- vacuuming floor/dust
- ac 2.5hp
- ac 1.0hp x2unit

Even if it is turn on at the same the MCB should trip, not the TNB fuse.

Did you check the old TNB fuse amp rating and is the new TNB fuse amp is 63A?

tbh.. i ain't sure the existing and replaced fuse is how many A
but from the pic.. confirmed it is 63A?
maybe i should buy one for standby.. how much would it cost?

Err..I thought you bought yourself..😅

Fuse amp rating is very² important, too high or too low is not good.
It protects both circuit and equipment.

Better check properly or better ask electrician to check overall.
If the old TNB fuse amp is 63A then better replace the MCB as well.

This post has been edited by juzmafia: Feb 15 2022, 03:35 PM

hmm but as u mentioned the mcb is already 63a?
then i jz need to confirm the fuse is 63a too, right?

Ya but if your old TNB fuse is 63A then during overload the MCB should trip earlier because it is the first defence for your house circuit. If MCB fail then the tnb fuse will trip(blown)

That's why if your old TNB fuse is using 63A(which i think it was) then MCB has failed to protect so better replace it. Better be safe than sorry.

..or another reason for the fuse blown is due to short-circuits happen between the TNB fuse/meter and Main DB.
Can refer this thread: https://forum.lowyat.net/topic/3973648/all

This post has been edited by juzmafia: Feb 15 2022, 05:29 PM

Ok la new place so we will rule out colonial era wiring and PPR flat which may be on 40 supply.
Most new places should be 63A supply.

Original DB came with 63A rated big blocks so it reaffirms circumstantial evidence above. If you have 40A big blocks that would be cause for concern. 63A big block should be ok as, costing wise they cost more than 40A big block equivalents and nobody would overspec..unless really clearance sale.

The TNB cutout fuse is quite slow.. If the MCBs dont trip but the fuse trip it might be a slow overload.. so happen all devices kick on at same instant. C curve MCB Imax is 5x to 10x rated.

I would like to dig whats on the 32A 3rd party additional circuit MCB.
Is that for water heater? The DB box is technically cost cutting and fails code "Electricity Regulations 1994" as NO 30mA RCD, NO 10mA RCD for water heater.

This post has been edited by ceo684: Feb 15 2022, 08:29 PM

I am having sound and a little bit of spark coming out of the Fuse Box also. Can I get my electrician to change that Fuse box only? the TNB meter seems to be fine

Before meter main fuse? that is TNB portion. call TNB to replace.

if its the DB box one AFTER the meter (homeowner part) then u replace.

This is a std fuse 63A perphase from TNB. You cannot replace it with higher Amp.

To solve it, apply for 3 phase. Each phase 63A x 3.