Heard that the water heater operates on mechanical RCD (residual current device) is much safer than electronic RCD. Any good brand and model comes with mechanical RCD? Is it more expensive?

I just worried that the electronic one may malfunction which cause shower electrocution whereas mechanical one when tripped, the power is surely cut off. Is that true?

If not using the mechanical RCD one, what is the best practice before safely using water heater? How often do we need to press test button?

This post has been edited by goolie: Sep 13 2023, 11:24 AM

Personally I like the mechanical type, so I always use Panasonic one.

Recently I need a rain shower type without built-in pump but Panasonic doesn't have this. So I got 1 from Joven which also comes with mechanical type. But haven't use it yet so can't comment much on it.

I'm also interested in Joven. Can i know which model comes with mechanical type?

I bought this one

https://joven-electric.com/product/instant-...series/sc33m-rs

How can we know it's mechamical coz it never stated in the spec?

you can see from the picture, there's a small level for the reset. or go to those shops and check it out physically

u mean the reset button as highlighted? Every water heater that comes with reset button will surely a mechanical one?

I think if the reset is a button not push in mechanical, then the cutoff mechanism will not be mechanical but electronics. Not to be confused with Test button

How to differentiate push vs button? from the layout we can know? Do u have any good example?

I go to the Joven link provide and I see this picture. SO, it must be mechanical When the Test button is pushed, the plastic level will jot out like in the picture I believe.



This post has been edited by Zot: Sep 14 2023, 10:29 AM

correct, the reset mechanism will tell you which type is it.

but just for your info, i bought 2 units and just got them installed. 1 of it got the reset problem where if i press the button on the front panel, it will not trip. but if i open the cover and press directly on the elcb, it will work. meaning the mechanical link in between is not properly designed or the alignment is out. will need to call them for warranty service. the engineering is still not as good as panasonic where i have used a few units since 20 years ago without any issues.

Ok, good. Do you know what is the purpose of 10mA(See this picture)? The seller send it to me and said all Joven model got this. Does it serve same purpose as mechanical RCD?

10mA is required for protection, anything above it will not be sensitive enough to protect the user from electrical leakage. it's also specified in the ST guide

Think of it this way
ELCB = only jaga the front gate of a factory.
If things go missing via the back gate nothing happens
it only works if leakage goes through E line
if leak thru human, human is not E line


whereas

RCD (fitted inside the DB box)
is like the airport screening machines.. no funny thing can happen.

correct, the one at the heater is only like for extra protection. the DB will still have the 10mA RCD or RCBO if got space constraint

so the one at the heater shall not be higher than 10mA else it will serve no purpose at all

This post has been edited by lowyat101: Sep 14 2023, 11:53 AM

btw from the picture of the "ELCB", i see that actually it's connected to both live and neutral, not to the earth. so it looks like it's in fact a RCD and not ELCB since at this moment the "real" ELCB should be no more available in the market.

any electrical engineers here can comment on this?

for your info, the reason for 10mA rating



ignore the typos

This post has been edited by lowyat101: Sep 14 2023, 12:25 PM

Ok, RCD in DB box is airport screening machine
ELCB jaga front gate of entrance

Then how about mechanical RCD in water heater that we mentioned earlier? Why it has advantage than electronic RCD?

This post has been edited by goolie: Sep 14 2023, 12:51 PM

Inside WH one, you must triple check and confirmsure that it is actually an RCD and not an ELCB.
Personally I don't trust the WH people to put a good one in.

I have no qualms running old WH (National since 1995), but on the RCD side I retrofitted in the 10mA (for WH) and whole house is using 30mA, can say double safety in the DB box.
Well below the death-point of 50mA.

Mechanical trip characteristics are more reproducible. Electronics fail too

This post has been edited by ceo684: Sep 14 2023, 12:58 PM

I confirmed that it's ELCB. See the picture inside WH. So, it's not safety to use? Should I change my decision to Not To Buy?

see my observations as per the previous post above, it should be a RCD, pending confirmation from electrical engineers

This post has been edited by lowyat101: Sep 14 2023, 01:05 PM

ok found this online, maybe it explains why the manufacturer is still putting the wording ELCB on it while it's actually an RCD

A good indicator that an instant water heater is using a Mechanical RCD instead of an Electronic RCD is that Mechanical RCDs come with a lever, while Electronic RCDs are button activated, as mentioned by @lowyat101 and @Zot.

Some Panasonic models have an RCD button that when pressed, a lever will pop out. Those are considered Mechanical RCD too, not Electronic RCD.

I think only a few brands are using Mechanical RCDs, including
i. All PANASONIC models, eg. their newest model U-Series ( Lazada / Shopee )
ii. Some JOVEN models, the ones with RCD lever not RCD button, eg. the one shared by @lowyat101, SC33 Series ( Lazada / Shopee )
iii. Some CENTON models, the ones with RCD lever not RCD button, eg. Vintage Series ( Lazada / Shopee )





@lowyat101 are u referring to this section of the ST guideline? If yes, it is referring to RCD requirement OUTSIDE and not part of the instant water heater, while the picture shared by @goolie is the internal RCD inside the water heater. Requirement for the external RCD for water heater connection is 10mA as stated in the ST guideline, while internal RCD inside the water heater only requires 15mA.



Not quite right. If I am correct, majority of the SIRIM certified instant water heaters in Malaysia are using 15mA internal RCD, including PANASONIC, ALPHA, CENTON, and many more. I think only JOVEN is using 10mA internal RCD. U can actually open up the instant water heater cover and check on the RCD spec.

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

I see, didn't check through the ST guide in details so not aware of the 15mA requirement

But logically, if upstream protection is more sensitive than downstream then it looks like the downstream one will never get to work, unless they are of different mechanism. Maybe someone familiar with this can share some info for our knowledge

Hard to tell from picture. Perhaps it is not wired properly

Originally the ELCB is voltage triggered device. Once current flow in earth circuitry, it will produce the voltage to trigger trip mechanism in ELCB. Later current triggered ELCB was developed. So, there are two types of ELCB, voltage and current triggered ELCB. The current one is renamed as RCCB or RCD.

However I doubt it is an RCD here.

However Pana says they only have ELB not RCD.
https://eng-au.faq.panasonic.com/app/answer...what-is-rcd-%3F

Ultimately I don't trust anything in bathroom wet area, all the humidity etc for my "safety belt".
I will still strongly recommend having a proper RCD (VI type) fitted at DB box

10mA RCD, VI type
[ABB]
https://shopee.com.my/ABB-RCCB-ELCB-F202-AC...113.10546714691

[or the Hager equivalent]
https://shopee.com.my/HAGER-CC225B-25A-2-PO...9918.9413541871?

Schneider one not sure whether it is the VI or VD type. Because the shopee mall one never write the P/N, unable to tell.
VI= Voltage independent Residual current tripping technology

and if no space in DB box, the next best is to have 10mA RCBO fitted.

https://shopee.com.my/-EZ9D16625-Schneider-...4397.8516252845

Because whatever inside the WH clearly did not protect said instances from happening
1. https://www.nst.com.my/news/nation/2020/08/...e-electrocution

2. https://www.channelnewsasia.com/singapore/e...d-wires-2551426

in this case cables are badly burnt
so when you have a voltage-dependent RCD it may fail to operate
however, having any 10mA RCD fitted at DB box is still much better than no 10mA RCD at all.

This post has been edited by ceo684: Sep 14 2023, 02:28 PM

The house RCD has higher current trigger level to prevent false trigger due to accumulated leakage current in appliances. TNB guidelines shows 2 RCDs:
1) 100mA trip current for wires to lighting and dedicated power outlets such as for air-cond, water heater, etc.
2) 30mA tripp current for power outlets such as 13A sockets for universal use.

As for the water heater, another 10mA RCD is recommended to be install for each water heater..

For me either ELCB or RCD, both can be unsafe. Most importantly is to regularly check if they function properly. The ELCB depends on house grounding. Over years the house grounding can fail due to corrosion perhaps. There RCD can also fail to trip due to malfunctioned.

In water heater electrocution, I read that 100% is due to using conductive hose with conductive shower head, which is basically metal. Nowadays all comes with rubber/silicone hose. Many say ELCB not safe but for me, it is still okay. WH body is plastic. Metal part inside the WH which is the heater itself is grounded. If there is shorted, the ELCB is triggered. The RCD operates in different way to prevent shock which is also no problem. However, normal RCD cannot detect faulty unit. Say the WH runs at 3kW, but when the current goes to 5kW it will not trip RCD because the supply and return currents are still balance . Once the current goes over the MCB, then the MCB in DB box will trip. So, still safe to some extend.

Like I said the most important thing to ensure that those safety device performed normally with regular testing.

Fixed. That is based on Msia's ER 1994 regulations which is outdated AF


which the MS1979 COP references as well


meanwhile in SG 2023..
 Circular_RD_E01_2023_ELISE.pdf ( 247.6k ) Number of downloads: 8


This post has been edited by ceo684: Sep 14 2023, 04:15 PM