Hi all, i called a contractor to come to my house for renovation. my problem here is wiring.

he said my house air cond point is "not a proper point". Need to "re-pull" the new points to the main swicth outside the house (sorry as I do not know the jargon or the terms for house renovation. hope you guys understand).

So, he said need to add "new points" and the charges are base on the number of points. But, my house ady got existing points for air cond. I know air cond point is stronger current with "red colour thingy light". I know if i wanna install a air cond on my dining area, i need the point as there is non!.

But this contractor say my whole house points are "improper"and need to change everything and "re-pull to the outside main switch.

Im not sure wether what he say is correct and I just noob.
or he wanna earn more by suggesting me to change this and that?

pictures as attached and kindly enlighten me if im just noob.

Edited : add the pictures where the air cond is use last time.

This post has been edited by BboyDora: Aug 16 2022, 07:53 PM


Attached thumbnail(s)

all the points with these "red colour light"on the wall.


Attached thumbnail(s)

Option A:
- ask him to explain again to you, ask clearly and as slowly as needed for you to understand.
- write notes, draw diagrams, take pictures as your contractor explains
- it's within your right as customer/client
- if your contractor is genuine and honest when he initially tell you of these problems... he should not mind doing this
- with sufficient information... you can refine your online search better

Option B:
- seek consultation from another licensed wiring/chargeman

Usually need to pull direct to the circuit breaker so that dedicated wire aka current goes to your Aircon.

You don't want high power current being share with other appliances.

If new hse check the plan. If old hse you need good electrician to advice and check.

If hse is 3 phase then less problem.

Energy Commission - Online System: Senarai Kontraktor Berdaftar-- https://ecos.st.gov.my/ms/web/guest/senarai...ktrik-berdaftar

I dont think many electrician will register there

It's hard to tell from the picture but few questions..

Is this house a newly bought used unit, or you been staying here for years? You probably have the history of some setup like the aircon, but doesn't matter.


Try to understand the requirements of aircon nowadays, then it is easier to gauge your current position on how far you are from the correct setup.

1. AC point Should be a dedicated wire directly to MCB connected to a 20A switch - wire size should be 4mm now according to ST guideline.

This is the specifications from the ST wiring guidelines you linked to in another thread. As you can see, air cond units of 2 HP (or below) are allowed 2.5 mm² wiring


Edit: link to the ST document https://www.st.gov.my/en/contents/files/dow...N_DOMESTIK1.pdf page 29

This post has been edited by stormer.lyn: Aug 15 2022, 08:15 AM

Show a picture of your switch box n it's diagram if got any

It is allowed but if you are buying a house from the developer now they should be fitting with a 4mm regardless of what - also considering if you are pulling a new wire why not just go for 4mm straight as you will not be straining the wire too much if you on your aircon for far too long hours - also for those who frequently setting the temperature low (than what the ac can actually deliver) would be straining the wire for too many hours as the compressor would not stop. This is the reason why government had changed in this 2021 rule. THis has not factored in the wire quality used by the electrician - which to me the minimum should be Caramay or Mega.

He just say "all these are improper wiring and points"which make me bizarre . I say got points ady oh... he say yes, but "improper".

Yes. the house is 3 phase.

it is not a old house. 7 years only. consider not really old i think

Its a subsale house. Got tenant who live before. the wire you see in the pictures are actually got air cond last time. when the tenant move out, he take the air cond away.

now my question is why the contractor say all the points "are improper"and want me to "pull"the new points?

thank you for the technical reply.

Just wanted to know why the contractor want me to "pull"the new points when the house ady had existing points and wiring.

Can you snap a photo of your DB and post it here?

Please use the "attachment" function so that the picture looks clearer.

if that switch aircond already put there before and previous owner already use that as aircond switch. should be able to reuse back the wiring, unless the wire is smaller than 2.5mm follow the ST standard.

so that contractor might looking for more job for more money . only they know

if got point than just install aircond and get it running

may i know what is Db stand for?

This is the main reason i post this thread to know is it true for this.
takut kena conned.

all points need to add are freaking expensive.

i had added the new photos on the 1st post where the air cond is.

It is the distribution box - usually in the store room, can you snap a clear photo and share it here?

That's an example of an electrical schematic, not the rules for what wires can be used. But if you are going 4 mm², then why not over spec even more to 6 mm²? Must be better with even less "straining", right?

The fact is over speccing is not always a good thing to do. Just this thread is evidence of budget being a consideration for wiring works because not everyone has an unlimited budget or unlimited time. And since ST allows 2.5 mm² wiring for air conds 2 HP (or less), that would be what I recommend. Empirical decision (after taking into account the maximum current draw, the voltage drop across the wire, and the temperature rise of the wire), not what I feel is right.

You had this very same question earlier this year, and so good to know that you now have developed your own opinion on the matter. As for me, I am perfectly fine pulling 16 A through a quality 2.5 mm² cable (Mega, Southern or Fajar, as I spec for all my jobs) and don't consider it "straining" the cable according to the relevant ST/IEC standards. YMMV

6mm² would be an overkill in my opinion and the pricing are usually far different. For 4mm² if you are getting a proper price from a proper electrician the price different is not far to consider - taking account into some users who frequently use an aircon in a way that does not allow the compressor to cut off, in fact a 4mm² would present a lower-cost setup in the long run. It depends on how you calculate as some people might decide to sell a house after 5 years so investing slightttttly further does not make sense.
4mm is not really "overspeccing" if you are considering that ST rules for all the developers are now to go for 4mm².
To be exact in finding the best you would have to look into the entire setup - some older air conditioning systems for 1hp would consumes about almost a 2hp similar power, and some 2hp would consumes about 3hp like today's aircon system.

ST rule on the wire size is always "minimum" or the word "minima" so I would beg to differ that 4mm² is overspeccing, but 6mm² would be an overkill in my opinion.

Glad you took the effort to look for my old comment - yes throughout these few months I had decided to do a lot of learnings because I need to govern how my house wiring is setup and even doing inspection in my existing and other older houses which I stayed. These knowledge also helped me to argue with many different wiremen (when I decided to approach them to do re-setup some areas which I felt can potentially be hazardous) - 9 out of 10 wiremen insisted 10mA water heater RCCB is bullshit, suggested nothing lower than 100ma sensitivity. 7 of them had no idea what is RCBO. Was glad I learned a lot from CEO and revisited some of her sharing time after time to calibrate my understanding of what I read which were all true.

As I mentioned, the key word by "ST" is minima and you need to factoring into the economical and supply chain issue when ST are spec-cing all these so it is up to you to find the "optimum" setup which suits your usage - Minimum vs Optimum vs Overkill. A good example is a 100mA RCCB is still allowed in Malaysia where as in Singapore standard is a maximum 30mA only - is 30mA sensitivity an overspeccing?

Anyway, I would say most people visiting the forums would benefit from knowing the "must do" and "good to do" and helped them to be able to explore more, and then making an informed decision. This makes the forum an interesting place to share and learn from each other. I benefitted from it and we all should together.


This post has been edited by davidlow7: Aug 18 2022, 09:52 AM

The 2.5mm² in theory can go up to 22A but in real world many other factors affects the rating. Most significant would be the ambient temperature. Rating on chart m=normally for 25ºC free air. When wire in conduit the rating will drop quite significant because there are other wires that contribute to heat. During operation also the wire heats. The longer the run the more drop in rating. I would agree with you that for 3-pin sockets the 4mm² would be better option no matter what. You don;t know in future what you would use the socket for.

As for the RCCB, it is not about the mA alone. If you look at the ST recommendation, there are two RCCB. The 30mA are monitoring the 3 pin sockets while the 100mA side are general for lighting, fan air-cond and water heater.

As I can see from here the inductive load as put under 100mA. The reason would be to prevent unnecessary tripping during current surge the instant the inductive load is switched on. The 100mA will still give certain degree of protection when it is not possible to use 30mA. Another alternative is to use RCCB with different tripping curve. Type K will trip extremely fast and suitable for sensitive electronics devices. Normally you will see Type C which will trip instantly at 5~10 rated current.

One thing to note that the RCCB will not protect you from Live-Neutral shock.

Because the device thought you were the electrical appliance itself

This post has been edited by davidlow7: Aug 18 2022, 10:03 PM