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.

Salute to ceo684

Kudos to Sister ceo684

In short, buy a new reputable water heater for life sake

1. Definitely get a new water heater. That model is too old, not worth it to repair (but maybe keep it, and sell it to some museum or antique cafe in the future haha).

2. If the current water heater is not hot enough, check what's its power rating in kW (might be a 3.6kW), and get a higher kW water heater. These few weeks are rainy season, so water source is usually colder as well. If 3.6kW is not hot enough, u might want to get a 4.2kW to 5.4kW water heater, PANASONIC, CENTON, JOVEN should have these ranges.

3. Get a certified electrician to check and make sure all power connection are up to specs, including MCB, power cables (Suruhanjaya Tenaga recommends 4mm), STRICTLY NO PLUG+SOCKET CONNECTION IN THE BATHROOM (you can use the same junction box and replace it with CENTON SplashProof Connector as what @ceo684 mentioned, can easily purchase from Shopee here).

4. Use non-conductive hose / pipings.

Thank you sharing knowledge.

May I know:
1) why ST allows 100mA main RCD (or even 300mA as I saw in some houses) when >50mA leakage is fatal?

2) when RCD ages, as in spring weakens, will it be easier to fail safe (trip off) or it doesn't trip easily? I'm thinking that if it's the former, it's safer albeit mote troublesome.

for now
just buy any panasonic water heater with the ELB button on the front panel . / earth leakage test button .
pana WH have elcb for 15mA inbuilt hence not too worried about safety of this WH .
but you need to test the function / depress the button Monthly .

you need to test your SMC 40A RCCB at the DB box , regularly too as i see this is an old house /old DB box etc....
if you have budget then time to change this RCCB too.

ST recommend 100mA RCD / for whole house installed in the DB box.

some house use 300mA cos maybe they dont know the standard or got scam by the electrician .

2/ if the mechanical inside fail then it will not trip when you press test button.
if old RCD i would think the leakage current detect limit will be off .

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

TS MIA.

Not missing but busy.

I apologize for not replying.The updates

1.Sunday no technician.So I suggest to increase the heater to 75% hotter ( basic 50% before it get less hot ) and spray into the water tub.I confirm that the water is not hot and I forgot to mention , the water flow is also slow.
2.Monday call 3 technician , all 3 said no need to put extra RCCB outside since all new or old water heater have Elcb build in.All 3 technician said something stuck cause it to get water not hot.
3.Tuesday , Call again to main joven and panasonic technician for repair but need to book the time next week and the cs said go to electrical shop and choose a model
4.Yesterday plan to go out and have a look for the model , heavy rain , didn't go out.
5.Today , see whether still rain or not at the evening. as what Momo33 said , buy water heater first , then only find a good technician.
All technician also didn't recommend to have an extra RCCB , i really don't know why as they said all buid in, no need anything extra.

As some technician told us better change but some said can fix.Most of them doesn't have cert or just normal electrical technician.
I also don't know which decision to choose where the water heater is less hot and water flow very slow.If water flow slowly should be much hotter.
Anyone know what is the reason of part failure when water heater not getting hot ?

Now finding a good water heater but budget not over rm400.
Any suggestion for DH-3MS1 and DH-3N series ?

Thanks , will reply to you all but I don't really understand much on those DB and model and brand.I need to research more into it.SOrry for not updating in time and thank you again

water flow weak most probably pipes are block partially due to old pipes / house , to confirm need to check if the water input to WH is strong
or the WH itself . the mesh filter at the input control may be clog of sand particles . need cleaning.
or the WH power control /temp control mechanism is faulty cos to old .

if your water input is strong flow then get the dh-3m , non pump.

pana WH do have 15mA elcb built in .
so a RCCB specially for WH is optional up to you /budget.


This post has been edited by Momo33: Oct 20 2022, 08:14 AM

Ts can unscrew the pipe connector to confirm the waterflow.

If is strong, water heater problem.

If slow, piping problem, then is not water heater. Replacing it wont resolve the problem.

This post has been edited by mini orchard: Oct 20 2022, 08:08 AM

yes , one can try use 30mA RCCB at the DB box.
the issue will be more power trips . as in Msia we do have many lightning storms . and if you are not home
the food in the fridge will go bad.

the thing about 30mA for 13 A SSO really how many house implement this . even in todays new houses majority
dont have.
so how did they pass the tnb inspection /CF and is it really necessary . i dont really know.


This post has been edited by Momo33: Oct 20 2022, 08:22 AM

Hi ceo. I've got a question on point 3 of yours. How do you add the 10ma RCD under the 30ma/100ma RCD? my electrician told me if I do a hierarchy level that will cause side effects. eg. they trip each other off. so he told me to install flat level instead. eg. the rcds are totally isolated.

they will not trip each other off.

example if there is leakage of 20mA in the WH , only the 10 mA RCD will trip.

Actually ST requirements are 100mA for lighting and 30mA for plug points (power points for equipment easily accessible by hand). In this case, 100mA main RCDs are acceptable, provided that you have 30mA to cover the plug points in addition to the main RCD. If there is only main RCD it has to be a maximum of 30mA, but ST doesn't really recommend 1 RCD for the whole DB.

Of course, this is in addition to water heater circuits which are required to be protected by 10mA RCD (dedicated).

Adding a 10mA RCD in cascade with a 30mA/100mA is not an issue. The device is meant to trip the power due to safety reasons, what may happen is that both may trip at the same time if there is a problem, which is more preferable to it not tripping when the problem occurs.

Doing it "flat" is of course preferable but will involve alot of work at the DB, which is dangerous if not done properly.

Both may still trip, due to tolerances of the device itself especially when 10mA and 30mA are quite close in rating. There is a proper way to do discrimination of tripping for the devices, but even without the discrimination it's still preferable to put them in cascade rather than not having sufficient protection.

ceo684 Is this the way to find certified electrician to check and install apartment DB and wiring?

https://ecos.st.gov.my/ms/web/guest/senarai...aftar-elektrik-

If the certified person do the job, then ok. If he send his foreign worker, lain cerita if he dont follow-up on the work done.

This post has been edited by mini orchard: Oct 20 2022, 01:29 PM