Actually most RCCB on local market is VI type, even the 10ma local branded China oem design. Only RCBO some is VI type. You can check on the diagram on the RCD. You can even test trip VI RCD using 1.5v battery, some will trip instantly & others will trip after current flow both direction once.

Actually ABB FH202 AC-63/0.03 does has anti nuisance tripping. You can search using its SKU at ABB website where it does list 250A max surge current. AP-R range is their high immunity model and usually hard to find ready stock. If you have excessive tripping during lightning that not even close by, it is usually due leakage/short from neutral to earth that high resistance enough preventing it from tripping the RCCB on normal days. Only the lowest end consumer RCCB (for 30ma/100ma) don't have anti nuisance tripping.

This post has been edited by jio: Aug 30 2023, 09:34 PM

I don't recommend these kind of voltage protection for power main due to its design. There is risk of damaged contact of the relay, either high resistance (main mcb/mccb won't trip due to current limited in event of short circuit) or fused contact.

Relay type (voltage or phase sequence) + shunt trip coil will be the safer choice. There is shunt trip addon for MCB depending on brand. For 3 phase with MCCB, use phase sequence relay.

If the water heater is on MCB C16 & washing machine is on C10, then it is kinda safe but not recommend if you want to upgrade to higher power water heater or dryer. And electrician tend to shortcut loop from 1 socket to another without checking. You will still need a new cables from DB to the socket outlet if it doesn't exist in the first place.

You can have 40A 10ma RCCB such as Hager CCA540D support 2xC20 circuits if that what you prefer but it will cost about 2x Hager 16A/25A 10ma RCCB.

Maxguard 25A 10ma RCCB is under 60 & 16A 10ma RCBO is under 65.

This post has been edited by jio: May 3 2024, 11:21 PM

Check the existing condition during normal peak usage using leakage clamp meter. If the standing leakage current is below 30% of the new RCCB, then you can proceed. Above 50% I don't recommend as the RCCB will trip at 80% or even as low as 70% of the RCCB rating. Use leakage clamp meter with 40mm or slightly larger jaw as you have to clamp 3 phase + neutral. You can get Multi M-140 for MYR320.

WTF are you using isolator as main switch? Use 2P MCB please. In the past long ago isolator switch was used as main switch but it is always with fuse (integrated or separate). It is long replaced with MCB, fuse holder etc. Do not use main switch without overcurrent protection.

You need the overcurrent protection which the isolator switch lack. I recommend 2P MCB instead of fuse as I've seen fuse being temporarily bypassed during emergency (burnt fuse but no replacement fuse available) which supposed to be replaced but totally forgotten/ignored by the owner.

For your case you can either
1. Replace it with 2P MCB or switchfuse
or
2. Add fuseholder (technically you can substitute this with 1P MCB but you will as well replace the isolator with 2P MCB).

Edit: The incoming seems to be connected to the RCCB. Is this sub-DB instead of the main DB?

This post has been edited by jio: Jul 19 2024, 10:50 PM

Ring circuit is actually good for when you need a lot of socket outlets in a room ( & won't be adding anymore) but the total load is not high. I would pair 2.5mm² ring with 10ma C25 RCBO with FE as this is the most easily available 10ma RCBO with FE. This is useful for washing machine + dryer & bedroom with socket outlet in bathroom. Ring circuit is actually easier for me to check the continuity/resistance of the wiring. But if you're using Sirim non-JKR cable, you must not use 2.5mm² cable with C32 breaker as most of them actually 14AWG (~80% cross section area & ~90% current capacity of actual 2.5mm²). I don't like circuit spanning multiple area/room. There is no point using 4mm² ring circuit for socket outlets even for kitchen. Just use multiple C20/25 4mm² radial circuit. For 13A plug appliances, they are usually rated for <10A (2-2.4KW) for long continuous operation type or <13A (3KW) for short operation type. Use double socket outlets to distinguish the circuit grouping.

As long as you never thermally overload cable and protect it from the environment, the cable insulation can easily last >30years even for sirim certified non-JKR cable. This is easy to follow for fixed appliance each having it's own circuit even after derating the cable for the ambient temperature (I use 50°C for hot kitchen and roof ceiling). Socket outlet circuit is where people mess up with excessive looping or not know the circuit grouping of the socket outlets. You might have 3 separate C20 2.5mm² circuits, but that won't stop them from overloading 1 of the circuits with powers strip extension. To prevent the cable the from being overloaded, just make sure the MCB overload current (1.45x) didn't exceed the cable current carrying capacity.