ozak & Richard - thanks for the inputs.

How do i check if the heater is equipped with RCD 30mA?

The water heater must be equipt with a 10mA RCD..

That is the current mandatory requirement set by Suruhanjaya Tenaga..

Edit.. the RCD will usually have a test button to press ..
Leaking a small current to ground thus tripping out the electricity supply..

If it doesn't trip then the earth wiring is suspect or the RCD is faulty..

This post has been edited by Richard: Jun 28 2017, 09:31 AM

my old heater states ELCB instead.
nothing about RCD/RCCB.

An ELCB works with voltage difference..

An RCD works with residual current difference..

As long as your earth wiring is solid, your wiring insulation is good and your protection devices work properly you are safe..

Recommended cables for installation of water heater.

It is quite difficult to find Flexible 3 core 2.5mm 50/0.25 cable by the metre at electrical shop. Mostly they want to sell in a roll which is about 50 feet. As a result, most DIY ended up using 3 core 70/0.0076 (70/0.193) flexible cable for installation of water heater. In my opinion, the 3 core 2.5mm 50/0.25 is a better choice.

so you saying the water heater has auto reboil based on the temperature drop, and also has a manual switch you can turn off the heater? what if it's shared between 2 bathrooms, how would the switch work? since a 2 way switch would mean the on/off can be up or down depending how the other switch being operated.

if no switch, means it's always on, what if there are water cut and the tank become empty, does the heater has a monitor to cut off when water is below certain limits?

also how reliable are the temperature monitor and is there any cut off safety function from overheating?

coz tank heater sounds quite new to me.

can explain how to read the cables for conduit & flexible cables? are both multicore cables?

Hi need advise here. Last year my newly installed water heater caused my mcb to make loud buzzing sound when turn on. As suggested by ozak, i ask electrician to change mcb and the sound stop. And today, after 1year, i just noticed that the buzzing sound coming back but it was less noise compare to previous. So was it normal or is there any other issue causing mcb to keep getting spoilt?

It is not getting spoil but the contact inside the MCB dirty. It cover with carbon which cause the static jump between. That cause the buzzer sound.

Do you always ON/OFF the MCB ?

Try ask the electrician check the wire secure to the mcb correctly. Screw tightly the wire on the mcb. Loose wire may cause the same problem.

Change to more good quality mcb.

Makesure the MCB rate at C20 (20A).

for reference

Guideline for The Design, Installation, Inspection, Testing, Operation and Maintenance of Water Heater Systems

http://www.st.gov.my/index.php/en/download...-heater-systems

Ok, will request my eletrician to change & secure properly. Is there any other possibilites that might causing this? Btw, the water heater adapter was split out from the fridge adapter. Would this be root cause?

It is better for the heater to run the wiring separately. I not sure will this cause by the fridge.

You can try to run the fridge separately by another wall socket. For a yrs and see what happen.

You never heard people have such problem with MCB only for heater.

Glad you got the warranty for your HVAC system

installed RCBO by schneider electric after finding out about it during archidex previously

Just to share from ST's (Suruhanjaya Tenaga) recommendations, here are a few installation details to take note of:

1. Cable/Power Supply for water heater should only come directly from the house's Distribution Board (DB). This power supply source cannot be shared, 1 supply direct to only 1 heater, and not tapped from the Aircond's socket or any other wall socket points.

2. To account for voltage drop, the cable length from DB to heater should not exceed 50m.

3. There should be at least 2 Residual Current Detector installed for protection, 1 nos 100mA for the mains (from TNB) into your DB, 1 more nos 10mA for the outgoing supply from your DB to the water heater. For the 100mA RCD, this is shared for your entire house. For the 10mA RCD, it should be 1 per heater, as per item no.1.

4. The cable/conductor size should be a minimum of 4mm2 for most instant water heaters in Msia (<5.0kW). This means that if you are using a PVC 3core cable (those grey cable with 3 in 1), it should be of the '56/0.30' size.

5. The Protective Earth should be a single run (green cable) as much as possible, and direct to your DB's Earth. That means you should minimise any 'sambung' cables, or to share the Earth with other power socket points in your house.

6. Lastly, there should be a certain IP rating to the socket used inside your toilet to connect the power supply to your water heater.

Hope this helps. The water heater is actually a very dangerous appliance which many people are not aware of. If installed simply, it is actually a time-bomb. Do pass these tips on to whoever who may need it, whether it is a new installation or an existing installation which may need correcting. Many houseowners are told by their electrical contractors or wiremen that so and so installation is correct or suitable but it might not really be the case.

This post has been edited by Jane's: Aug 8 2019, 02:52 PM

can share about this?

more details on this schneider electric website
https://www.se.com/my/en/work/products/product-launch/rcbo/

thanks! will give this a look

Any idea where can I buy this box?