Bro, I have seen 300mA RCCD being used in Sarawak. The developer and all other electricians we spoke to claim 3-phase power supply requires 300mA RCCD which I think is bollock because ST guidelines suggest 100mA max.

And there's no 10mA RCCD for water heater too.

ST guidelines and electrical safety guidelines say max sensitivity is 100mA for both 1P and 3P supplies.
For 3P, you can choose to install one 100mA rccb (if any phase is defective, you lose power to whole house) or 3x100mA rccb for each phase.

Yeah, ST still allows 100mA for lighting and AC.

House developers will always say if you use 30mA as main RCD, you can expect trips every 2-3 days.

That's a dilemma I'm facing. My house has just one main 300mA RCCB.
Really confused now with the options:
1) one main 30mA rccb and 10mA rccb for heater, but worried about frequent trips as double storey house tends to have more current imbalance due to more circuits/fixtures?

2) 100mA main rccb, 10mA rccb for WH, and swap SSO circuit MCBs with RCBOs - means aircon and lighting circuit protected by syok-sendiri 100mA main rccb.

Which option should I go for?

Also, will adding SPD at DB help with trip reduction especially during thunderstorm?

I'm leaning towards a main 30mA RCCB due to it being safer for the whole house and cheaper too.

When you said anti-nuisance, are you implying there are versions with or without this feature, or in general ABB/Hager has better anti-nuisance feature compared to other brands?
Asking because I checked with Shopee ABB official store seller, and they told me the model I'm interested doesn't have anti-nuisance trip feature.

https://shopee.com.my/ABB-RCCB-ELCB-FH204-A...8d-a9aef9a044be

They suggested adding auto recloser (almost RM1k), which could be my Plan B.

TIA

I don't understand this statement.

Should go for 0.01A or 10mA.