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?