Only fcking idiots (unqualified electricians) will put an insensitive RCD.
Coz not they die ma "not my house syndrome"

10mA RCD is "accepted standard" globally.

Yes the Pana DH-3MS1 will be the push start workhorse (M series w/o pump)
Any more u are literally paying for plastic cover changes (black version M, or anything else that cost more).
The Pana water heater design is tried and tested liao.

DH-3N (N series) the fancy colouring will wear out and become ugly over the years (think car door handle)

I relocated mine from 2000 era into my apartment. But ours in good shape lah.
1. Doesn't matter how old the heater is = having a 10mA RCD is of paramount importance. Too many ppl died in vain coz spent "a lot of money on the heater" YET "RM0 on the life protection" .

2. A RM280 heater (DH-3MS1) amortised over 5 years only RM56 a year; but usually they last at least 10 years .. only RM28 a year!

Yup a new one is safer
RM280 heater (DH-3MS1)
RM160 for ABB/Hager 10mA RCD - barang only provides BEST protection if money not a problem
-- RM100 for Schneider 10mA also can lah IF budget really a problem
-- RM61 for Maxguard 10mA RCBO -- I consider this Maxguard 10mA RCBO at the very bare minimum acceptable equipment. Can't afford this please dont use water heater.

Specific to your case, retrofitting will be required.

1. Need to check whether the existing LNE lines from DB box to that point in the shower (currently the round pin socket) is of sufficient wire gauge (2.5mm is bare min). Best advise (to fool proof it for next 30 years - run a new set of LNE cables from DB to the WH point in bathroom in 4.0mm Mega Kabel - its cheap if you do exposed/surface conduit).

1.1 Assuming 2.5mm existing cables, you can only buy the 3kW class heater, do not buy a 4800W one, it will catch fire.
1.2 At the bathroom last mile (where the round pin socket goes currently) - use a proper connector like the Centon water heater connector. Because ST regulation say must be direct connection - not socket. Loose connections cause fires.

2.0 At the DB box - retrofit in a quality 10mA RCD or RCBO, per each water heater. This is your life insurance for water heaters.

3.0 At the DB box - change the mains RCD (the one for whole house) to 30mA. This is 2nd line of defence. In case the 10mA failed to trip - the 30mA will catch it and trip (like a fail safe). If your 10mA failed, and whole house one is 100mA or 300mA which I suspect is the case - there is no backup - GG.com because >50mA leak thru human body, sayonara.

Why so many upgrades?
RCD also wears out after 30 years.. springs get weak etc.. aiya even original 1985 proton saga also need to change many things by now in 2022 lor.

This post has been edited by ceo684: Oct 16 2022, 04:41 PM

All RCDs in DB box. This is supposed to be "professionally installed equipment".
Any registered wireman/wirewoman (at least PW1 or PW3 cert) will be able to do it.
Working in DB box 1001 things can go wrong so please call a proper wireman. Coz its impossible to teach online, this is not the same as plumbing where the worst that can go wrong is you get yourself all wet.

All "user servicable items" like the 20A water heater switch will be right outside the bathroom.

1) It is not ST allow, it is because people want cheap and a black market of unlicensed unqualified "faux electricians" who know nuts exist

2) Do the price /30 years its already super cheap lah. Electrical safety kena question like FBI interrogation how to cari makan. It could actually be less sensitive due to metal spring lose tension.

This post has been edited by ceo684: Oct 20 2022, 01:29 AM

No, ST is not recommending specifically = 100mA whole house as the only RCD.

Like that, all the 13A SSO is illegal.

Yes I know can install 100mA whole house and another 30mA for 13A SSO.

But when MS1979 COP already mentioned maximum allowed tolerance = a 30mA settle all for whole house and fully compliant

Q: Why waste money with 100mA RCD whole house when it is largely redundant in 2022 scope of work - no more fluorescent lamps; waste DB box space
Or it is a ploy by RCD maker to sell more RCD?

This post has been edited by ceo684: Oct 20 2022, 01:32 AM

Actually not a problem.. 30mA built in modern day with anti nuisance trip trips very little

Correct. It should be tested as part of every new year/CNY routine maintenance.

This is a plan B solution, but for ease of troubleshooting it is safer to put everything at the main DB.

This post has been edited by ceo684: Oct 20 2022, 09:37 PM

Not many - its common in retrofitted and new build in SG
But in MY.. new builds got put but mainly China brands to save cost
Rarely you will get Schneider nowadays even for half million dollar place

30mA RCD, whole house (sum of all L - sum of all N return = acceptable losses)
Branches out from here to a bunch of little MCBs.
The 10mA is just for WH's own single L and single N. Input=output = acceptable losses and won't trip. IF the WH N is shared that means:
1) Installation is wrong in the first place
2) Useless for purpose of RCD, forever trip.
3) Most likely because it is not a dedicated LNE run from DB box to the WH unit.

Impossible they will trip each other off unless the WH circuit is shared neutral.

Correct.
And if there's a leakage of 20mA in a socket or light outlet unrelated to WH circuit, the 10mA will not trip.

No, this is acceptable.

Mana ada WH with built-in RCD.
ELCB got lah.

RCD is god tier protection (think of it as modern airbags)
ELCB is antiquated retired era stuff because "what if leakage don't leak nicely through Earth" aka leak elsewhere e.g. humans = don't t