Jan 1 2021, 10:56 PM
QUOTE(kirlcheah @ Dec 31 2020, 11:07 PM)
When you go to the shop to buy the 10mA to 30mA RCCB, this is designed for water heater. A single jolt of up to 50mA can actually kill us when there's a leakage from the water heater. When the 10mA or 30mA trip, it's designed to check for residual current so that anything over 10mA / 30mA will trip it to save your life.
Hence why only 10mA will be used for heater in case of water heater leakage. Mind you, installing a good RCCB would not save you if your house grounding wire is not good. You must remove the grounding cable from the electrode / grounding rod and test to get less than 10 ohm. This is dictated by ST. Less or equal to zero is the best and this is done for factories. This can be tested with a grounding meter. Please make sure to connect the cable back to grounding rod after opening it. Also, grounding cable must be at least 10mm cable or best is 16mm cable. Why this is needed to be this thick is because the grounding cable will have lower resistance and all voltage when hits your house during a lightning will travel via this cable to the grounding rod to be absorbed by earth. If you have a 1.5mm or 2.5mm or even 4mm, it will not work as good as a 10mm cable as the resistance is high thus the voltage will not use it as the main cable to travel to earth and will flow elsewhere into your house circuit.
A lot of people don't understand and says that this will trip easily is because they do not know what it's designed for. If your house grounding is good and the 10mA RCCB trips, means there's issue with the circuit and require your attention. Either there's a lightning strike or the cable been damaged by mouse etc. You have to test the cables to make sure it's good.
For house, the main RCCB should be at 100mA. Not 300mA. Those electrician who tells you your house need a 300mA, you better ask them to go and fly kite. 100mA is the maximum dictated by ST. Best is 30mA but it will always trip if there's lightning but if you have a 65kV Surge Arrestor installed, you should be alright without any RCCB trip cause the surge arrestor will absorb the voltage from the lightning. 45k is around RM500 plus. 65kV is around RM1000. Go figure. Buy only good MCB or RCCB with Sirim. There's a lot of fakes out there. EPS is low cost range. Buy Hager / Schneider. Hager is around RM8 for a MCB while Schneider is around RM 13 each. More expensive means it's more sensitive. EPS only cost RM4 dollars. I won't put my life in danger by using a MCB costing dollars....
RCD doesn't need earth to operate. 10A in must have >9.97A out for a 30mA RCD.Hence why only 10mA will be used for heater in case of water heater leakage. Mind you, installing a good RCCB would not save you if your house grounding wire is not good. You must remove the grounding cable from the electrode / grounding rod and test to get less than 10 ohm. This is dictated by ST. Less or equal to zero is the best and this is done for factories. This can be tested with a grounding meter. Please make sure to connect the cable back to grounding rod after opening it. Also, grounding cable must be at least 10mm cable or best is 16mm cable. Why this is needed to be this thick is because the grounding cable will have lower resistance and all voltage when hits your house during a lightning will travel via this cable to the grounding rod to be absorbed by earth. If you have a 1.5mm or 2.5mm or even 4mm, it will not work as good as a 10mm cable as the resistance is high thus the voltage will not use it as the main cable to travel to earth and will flow elsewhere into your house circuit.
A lot of people don't understand and says that this will trip easily is because they do not know what it's designed for. If your house grounding is good and the 10mA RCCB trips, means there's issue with the circuit and require your attention. Either there's a lightning strike or the cable been damaged by mouse etc. You have to test the cables to make sure it's good.
For house, the main RCCB should be at 100mA. Not 300mA. Those electrician who tells you your house need a 300mA, you better ask them to go and fly kite. 100mA is the maximum dictated by ST. Best is 30mA but it will always trip if there's lightning but if you have a 65kV Surge Arrestor installed, you should be alright without any RCCB trip cause the surge arrestor will absorb the voltage from the lightning. 45k is around RM500 plus. 65kV is around RM1000. Go figure. Buy only good MCB or RCCB with Sirim. There's a lot of fakes out there. EPS is low cost range. Buy Hager / Schneider. Hager is around RM8 for a MCB while Schneider is around RM 13 each. More expensive means it's more sensitive. EPS only cost RM4 dollars. I won't put my life in danger by using a MCB costing dollars....
ELCB needs earth to operate. This is why it has gone to the dinosaur age because a lousy ground will render ELCB useless.
MCB wise
I don't trust those ciplak brand MCB etc. There are a lot out there. Commonly available top-tier brands in MY are ABB Hager Schneider for around RM8 each (shopee online from electrical supply shop). I've a whole bag of Himel crap that the developer installed in my new apartment and I ripped whole thing out and replaced with metal DB box + top tier internals. Generally when top tier MCB is available for RM8 ea.. there is no point in buying crap for half the price. Most MCB are made in China even from top tier places.
In angmoh countries.. B curve MCB is used typically as the general use MCB (resistive loads such as water heater), C curve is for bigger induction load (special use/motors). Yes there's D curve (extreme heavy use for factory with huge motor).
Here general use is C curve
and I had to "special order" B curve siemens B16 MCB from RS components for my water heater (it being a resistive load doesn't require such high tripping characteristics of C curve.. B curve more than enough) cos its near to impossible to find a B curve MCB here in MY. Everything is C curve RCD wise
10mA for WH will not work well with shared neutral. Too much "interference with other circuit neutrals" (assume the faux electrician from previous owner time using shared neutral for WH) there. Whole hse using 30mA so its not leaking improperly. When I connect the WH in DOL (direct online) mode with my own 3 direct cables it works perfectly. For top tier brands some are still made in EU (France/Italy/Bulgaria).
For house use follow the angmoh countries..just use 30mA for whole house main RCD will give complete protection for each and any circuit downstream as 30mA will not kill you.
School requirement is 30mA in case student poke pens or pencils inside the SSO. Above 50mA, a leakage of 100mA or 300mA also doesnt matter, both also end up in coffin.
My personal opinion is that here our ST spec too "outdated for life preservation w.r.t. whole house RCD" as the risk is still the same whether u are using lights (change bulb) or 13A SSO (plug unplug stuff) whereby they use 100mA for lights and 30mA for 13A SSO
seems like they just wanna sell you another piece of RCD The ST spec for Water Heater requiring 10mA RCD is the only good part. 
30mA RCD does not always trip - only during severe thunderstorm.
I replaced my main RCD last year (2020) with a 2019 made 30mA RCD from ABB (got anti-nuisance trip) - actually the new one (even being 30mA) trips less during thunderstorms than the 1995 era 300mA which is only suitable for commercial/light industry usage.
This post has been edited by ceo684: Jan 1 2021, 11:16 PM
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