My neighbour house almost on fire last time due to wire melt while using some appliances , i think microwave.

Since this is very old house on taman area.. very long time ago
Wiring also start aging too

Guys, can suggest what wire to use that good handling appliances like aircond, hair dryer, washing machine, water heater etc

I want to adviced those nice folks on this wiring issue.. but i no idea to say

Plz help

Also DB box component like RCD, MCB can fail over time so for those >30 years already time to change lah. If planned right, medium (28 way) full DB box incl metal box should be 500-600 parts costing with ABB stuff. Hager also good but their RCD mahal sikit, so I usually do ABB.

If you want to do the work yourself, then I suggest you buy the wires by the roll, and not try to buy the exact length of cables you need. If there is extra cable, then just accept it as a loss and sell the extra to electricians, or to recycle centre.

You don't have to buy all the cables at once; buy 14 rolls*, use, and continue buying as you run out. It just means you have to make more trips to the shop/Sh.pee/Laz.da, but your excess wires will be minimum at the end.

You can try and estimate if you can save money as compared to hiring an electrician. NOTE : This is not a price quote.
First socket point = RM 150
Loop additional socket point from the first one = RM 100
First light point = RM 100
Loop additional lighting point from the first point = RM 70
Fan point = RM 100
Water heater point = RM 300
Air cond point = RM 200
Door bell point = RM 200
Auto gate = RM 450
Change DB = RM 1500
Take into account what your time is worth, and if you have the skills, manpower, and equipment, to take on this job yourself, and decide if it is worth it to you.

* _{1.5 mm² = 1 x red, 1 x yellow, 1 x blue, 2 x black, 2 x green = 7 rolls. Add the same colours for 2.5 mm² wire for a total of 14 rolls}

As I have always said, the low-class customer always looks at price first. Even the "YouTube famous" Malaysian solar installer says the same, and gives pointers on how to spot them.

What makes you think a qualified, competent electrician won't be using proper materials and proper installation procedures to complete their contract?

That is the flaw in your conclusion. You are confusing your opinion on being a cheapskate with reality. Quality customers actually look at quality-of-job first, price second. Even if funds are short, they will try to stretch, because quality, both for materials and installation, is worth paying for in the long run.

But anyway, it is a free market, and you are free to think the "bawah pokok electrician" is great, if that is what fulfills your needs.