1) Hi, I would like to change new water heater, I'm confusing to choose either Joven, Alpha, Rubine or Centon. Salesman keep on approach me Alpha and said others brands not secure like Alpha.

What I concern is which DC pump more powerful cause my water pressure bit low and I going to take rain shower series.


2) Lets say if I take 42kw heater, do I need to change MCB to 25mA? I had read previous post which advise to use 25mA based on Suruhanjaya Tenaga's guideline, but some of them tell me 10mA is enough for that. May I know which one is correct?


Appreciate for your advise.

This post has been edited by FyChai: Dec 28 2023, 12:00 PM

The 25mA and 10mA is the trigger point when the MCB tripped to protect people from electrocution. So, the 10mA is recommended to be installed at water heater by TNB.

The water heater circuit breaker is additional to the house MCB.

This post has been edited by Zot: Dec 28 2023, 12:07 PM

Here is the guideline from TNB

You can see where the 10mA breaker is.

Sorry I'm lost, I'm using C16 as photo, does it too high or low for the 42 kwh water heater? C16 mean for 16A right? ChatGPT ask me to get C25, salesman said C16 ok for it, so confusing. Appreciate for your reply.

There's discussions here.
https://forum.lowyat.net/index.php?act=ST&f=231&t=2107287

I had read that post, inside said 25A MCB RCB, but other post said 10mA, so which one should I use? C10 or C25?

A

This post has been edited by FyChai: Dec 29 2023, 12:20 AM

1. Are you gonna lay new cable to install the water heater?

2. mA should be 10 to protect from leakage, RCCB

3. A normally a dedicated 20A MCB / In your case 4200w should take 32A MCB with minimum 4mm cable

C16 OK for 3300W WH.
4200W WH pls run a new line (electrician required) with 6mmsq cable else you gonna burn down ur hse. Of coz salesman everything can, burn also not his place

Bathrooms with extremely low water pressure usually have issue turning on the water heaters, as most water heaters use flow switch to turn on (at minimum consistently maybe around 2 litres / minute water flow, and water heater's heating element and built-in pump might not turn on if water flow is lower than that).

But I saw CENTON has a newly launched instant water heater (Atlantis range, shown below) with a Pump Activator function, which when the button is pressed, it will manually jump starts only the built-in pump to increase water flow enough for the flow switch to turn on the water heater. I think this function should be more important for you. Here is the Shopee link if u need it - Shower Rail / Rainshower



I suggest u to only go for rainshower instant water heater if your original water flow is already sufficient, since built-in pump, regardless of whichever brand u buy, won't cater enough water pressure for your rainshower if your original water pressure is already low.

If rainshower is a must and your bathroom's water pressure is low, I suggest u to install those external booster pump like Grundfos instead (Shopee link here).





Table above and below is taken from Suruhanjaya Tenaga's guideline. So basically for instant water heaters (common ones are from 3.6kW to 4.5kW), they will require the MCBs / RCDs to be 25A rated with 10mA sensitivity (for appliances installed in wet areas). 25A is the current rating (In), 10mA is the trip sensitivity.

In conclusion, I think u will need a 25A rated current, 10mA sensitivity, double pole (cut live and neutral) RCD. Experts, please correct me if I am wrong.



This post has been edited by Selene Yeo: Dec 14 2024, 10:12 PM

Please do not confuse between RCD and MCB.

MCB you have now is a C16 to safely allow up to 16A LOAD.

RCD which you don't have now, and you will need, is a 10mA RCD rated to sense up to 25A, this is the bestest protection -
https://shopee.com.my/ABB-F202-25-0.01-ELCB...1856.9133931062

or this also can, if budget is an issue
https://shopee.com.my/Schneider-Easy9-25A-2...4033.3943044744

Failure to install a proper 10mA RCD will lead to unwanted outcome, usually death.
https://www.straitstimes.com/singapore/cour...oroners-inquiry
https://www.freemalaysiatoday.com/category/...ed-in-bathroom/

----------

Since we're here,
your existing installation is totally illegal, and is useless for human life protection.

3.5 RCDs and Direct Contact Shock Protection
The use of RCDs with rated residual operating current of 30mA or less are recognised as
additional protection against direct contact shock. Regulation 415.1.1 refers.
Direct contact shock is the result of persons or livestock inadvertently making contact with
normally live parts with one part of the body and, at the same time, making contact with
earth potential with another part of the body. Under these circumstances, the resulting
electric shock will be at full mains potential and the actual current flowing to earth will be
of the order 230mA because of the relatively high body impedance involved. It has already
been shown in Section 2.3 that currents as low as 40/50mA can result in electrocution.
Read more here https://forum.lowyat.net/index.php?showtopi...ost&p=106857006

This post has been edited by ceo684: Dec 29 2023, 12:43 AM


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4.2kW instant water heater should only require 4mmsq cable, not 6mmsq cable, according to Suruhanjaya Tenaga's table above. If I am reading the table correctly.

With the advent of fake cable and substandard cables nowadays, plus not being the installer meaning can't control the quality of cables being used, overspec is better. It doesn't cost much more.

A good reminder to always go for good quality cables, eg. like Fajar cables here - Shopee / Lazada

This post has been edited by Selene Yeo: Dec 14 2024, 10:11 PM

Do you mean run from DB to water heater?
The water heater at 1st floor, need to hack a lot if run a new line, any other way can do please?

This post has been edited by FyChai: Dec 29 2023, 08:54 AM

Currently I'm using Alpha S200EP with AC pump, the water from shower head can spray 4 feet height, I'm ok woth it, but not sure if DC pump suitable. My house is 20 years old, scaring install external pump from water tank will burst the piping joint.

This post has been edited by FyChai: Dec 29 2023, 08:53 AM

The DB is ori set from developer, I just add on 3 MCB on left hand side for dry and wet kitchen. May I know is that call MCCB for my current 63A breaker? If I change to 100mA, do I need to upgrade or remain 63A?






As per pic above, do I need to place 1 RCB for every floor? Or just for the cable which use for water heater?



Sorry lots of questions, i need more knowledge before asking a electrician to visit again. Previous electrician came to check and never mention about the 300mA of breaker and RCB until I find it myself.

You have been running your current water heater which is rated 3.5kW – 5.5kW for so many years already and your wire probably a 4mm² wire. I think it should be just fine to just use the same wire.
The wire can carry 32A roughly if it is inside tubing or directly nailed on or inside the wall cement wall. Your 4.2kW water heater will max at 18.3A @230V. I would consider it as continuous load current. So, I would derate wire requirement. 1.25 x 18.3 = 22.875A which i still within the wire load capability.

You need to install a 100mA RCD (not MCB as mentioned by ceo684. This is for safety against electrocution. You do not want any current more than 10mA run through your body if accidentally touch wire or if the water heater got leak current. You can put it on wall just before the 2 pole switch inside single breaker casing if you do not have space in main DB box.

Just for the water heater for safety. If use 10mA for whole house then you probably will experience unnecessary tripping

30mA not 100mA. Otherwise still fail on the Final Circuit for 13A SSO 30mA regulation.

Regulation aside.. 100mA trips after the 50mA threshold..


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The quality of components used are questionable if they already installed C16 MCB.

Your scope of work:

change the mains (entire house) RCD to 30mA.
install a new 10mA RCD for EACH WH (water heater) circuit.

You do not need a RCD for every floor.

Opps... I thought I typed 10mA .... did not check before posting.

This is for the water heater.

This post has been edited by Zot: Dec 29 2023, 02:22 PM

Do you mean this one change to 30mA? Remain 63A?
May I know what type of breaker is this? RCCB?

This post has been edited by FyChai: Dec 29 2023, 03:04 PM

Correct. Replace like for like since you have 63A three phase supply.
This is a RCD. The spec is 4P 63A 30mA (0.03A).
Estimated barang only- RM2xx for a good one from ABB/Hager.

https://shopee.com.my/ABB-FH204-63A-4P-300m...2787.3248905327

OK, thanks for your explanation.

1) I realise the Main MCB only C32, its it enough? Weird that my RCCB higher Amp than Main MCB. Do I need to upgrade also?

2) I checked online 3 phase should be 100A, any way to know my house is 63A or 100A supply?

3) Wireman ask me to change aircond and kitchen MCB to 32A, but i checked aircond for 1HP is 8A, it should be sufficient for current MCB (16A) right? Do I need to upgrade it also?

4) Since I'm upgrade MCB of water heater to 25A and RCD needed, do you think I just buy the RCBO 25A 10mA better?

5) My house area has thunderbolt fallen history, My house get hit once before and the outdoor TNB cable spoiled. Will it easily trip If I use 30mA for main RCCB?


Since I'm hiring wireman to upgrade it, hope can setup the DB as good as possible, technician cost quite expensive.

This post has been edited by FyChai: Dec 30 2023, 10:14 PM


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my circuit breaker panel already out of space. how do i addon RCD? can i install it at the water heater switch outside my bathroom?

Yes you can install near the water heater switch outside the bathroom. There are small casings that are meant to fit a single RCCB (2u size)
The other choice is to get a RCBO, and replace the MCB for the water heater that is in the DB. RCBOs are the same size as MCBs, and are meant to swap 1-to-1. RCBO are dual function devices, an MCB and an RCCB in one unit