Didn't see my own place blackout every 2-3days its a myth

Ok except the last one use 40A 0.03A

I believe you will have unnecessary tripping faults. You have made a common Neutral busbar for both the top RCCB (Marked "40A 30mA" - Let's call this RCCB1) and the bottom RCCB (Marked "63A 100mA or 40A 30mA" - Let's call this RCCB2)

This may happen : Current flows through RCCB1 live > MCB 16A > socket in room > appliance > Neutral wire back to DB > Neutral busbar > RCCB2 Neutral.
Your RCCBs will trip. You have to split the Neutral busbar for RCCB1 and RCCB2.

The WH Neutrals must be connected to the RCCB2 Neutral busbar, as the current to the WH originated from RCCB2.

Also, physically, when I am making the connections, I would connect the 10 mm² wires together. This is for the WH Live. In the drawing it is connected through the Live busbar at each end. Potentially the Live busbar will heat up.

Ok except the last one use 40A 0.03A

Yes, this diagram looks good. What I meant about the water heater live wire is in the picture below.



This is the physical connection of the wires. This way the Current to the WH doesn't go through the busbar, but goes wire-to-wire. If you look at a busbar, the bar is rated for 120A (example) but the tines are rated for the Current to an MCB only. They way wiremen stuff the incoming wire into the MCB and get it to distribute is dangerous in my opinion.

Sorry, a bit busy to get on LYN. In the marine line, many ships right now. But I'll try to get back to you asap if you have any further questions.

Mixing your neutrals BEFORE the RCD "checkpoint" has different implications.

U know how shops like genki sushi and sushi king charge for per-plate kaiten belt sushi?
RCD operates like u eat, u pay for your plate tower.
Now let's say I eat, I don't know you, but I put my plates into your table.

Yes the FH202 terminals are bidirectional from the diagram 1/2 2/1

SH201 without L better.

Old MCB u need to check for fakes as well. Since new MCB not expensive rm 8 a piece I would go for new “peace of mind” for 30 years

4.5kA vs 6kA short circuit withstand.

L is slightly cheaper.
The barang cost only 50c or rm1 a pc difference. I don't bother using 4.5ka SH201L because the small diff use 6kA SH201 better
The SH201L one is when "every cent is a problem" case when client very tight for money but its not worth stocking..
16mm x2 in that almost impossible to fit.
U forgot the up to.
Also note per each water heater = need its own unique unit of 10mA. Three WH = 3pcs 10mA.

[attachmentid=11482041]

Also note that this is 30 year old regulations (ER 1994) in the era of flourescent tubes and window-box type aircon  in 2023 one piece 30mA bao kah liao is perfect. Save space. Save time.
It is also illegal w.e.f July 2023 in SG to use anything other than a 30mA RCD for the main RCD. This is for safety reasons.
[attachmentid=11482043]
By right should be protected by 2 pcs of 40A MCB if 2 pcs of 10mm cable is used.
A 63A main switch does not protect any of the 10mm cable.
Going by principle of either FUSE PROTECT CABLE = OK and CABLE PROTECT FUSE = 🔥 this should be better managed especially by the tradespeople 

Loose cut (cut by 1m lengths) mega kabel 16mm only few ringgit even to order in the correct multi colours Red Yellow Blue Black..

** sorry, am typing on laptop quite hard to do the alt 0178 

I’m not in favour of this because it only has CE shiok sendiri mark. It’s not a proper Sirim or equivalent certification.

Yup all good 👍