Welcome Guest ( Log In | Register )

7 Pages « < 4 5 6 7 >Bottom

Outline · [ Standard ] · Linear+

> Home Electrical MCB, How to size Miniature Circuit Breaker

views
     
SUSslimey
post Oct 17 2018, 01:18 PM


*******
Senior Member
6,914 posts

Joined: Apr 2007
QUOTE(FrankieSiow @ Oct 17 2018, 10:24 AM)
Thank you for your slimey prompt response. I understand based on what you explained just now. Could you also enlighten me on questions below?

1) If I have extra space in DB and I choose to install the RCD at DB, will it be less effective compared to RCD nearer to water heater?
2) If I have to install at nearer to water heater, the RCD should be installed before the 20A switch as per sequence below?
    (Main RCD (30Amp) - Water Heater MCB- RCD(10Amp)-20A Switch-Water Heater Power Inlet)
3) I found Hager 2 Pole RCD only has 16A and 25A rating with 10mA tripping value, which one should I get for my 20A water heater? (See attached photo)

Cheers!  smile.gif
*
1. Negligible difference. But if the neutral to the water heater switch is shared with other stuff then it is rather troublesome or inconvenient. Either need to pull new neutral line or if not the rcd trip will cause other stuff shared on the neutral line to trip together.
2. No real difference before or after.
3. Erm....check the wire size going into the water heater. If less than 4mmsq do not use 25a unless it is already protected by a 20a mcb in the distribution board.
16a i think will trip if use full power of water heater.
FrankieSiow
post Oct 17 2018, 01:36 PM

Getting Started
**
Junior Member
51 posts

Joined: May 2012
QUOTE(slimey @ Oct 17 2018, 01:18 PM)
1.  Negligible difference. But if the neutral to the water heater switch is shared with other stuff then it is rather troublesome or inconvenient. Either need to pull new neutral line or if not the rcd trip will cause other stuff shared on the neutral line to trip together.
2. No real difference before or after.
3. Erm....check the wire size going into the water heater. If less than 4mmsq do not use 25a unless it is already protected by a 20a mcb in the distribution board.
16a i think will trip if use full power of water heater.
*
Really thanks for your explanation. I understand the whole concept already. I will discuss this with my electrician on this matter. smile.gif
SUSslimey
post Oct 17 2018, 01:39 PM


*******
Senior Member
6,914 posts

Joined: Apr 2007
QUOTE(FrankieSiow @ Oct 17 2018, 01:36 PM)
Really thanks for your explanation. I understand the whole concept already. I will discuss this with my electrician on this matter.  smile.gif
*
To add on. If trip the neutral without tripping the live of the appliance that share the neutral is dangerous.

All the neutral that share it will actually become live which is more dangerous than before.

And since you have 3 phase electric supply , kaboom if different phase mix into neutral line which lost the link to the main neutral link.

This post has been edited by slimey: Oct 17 2018, 01:43 PM
FrankieSiow
post Oct 17 2018, 02:05 PM

Getting Started
**
Junior Member
51 posts

Joined: May 2012
QUOTE(slimey @ Oct 17 2018, 01:39 PM)
To add on. If trip the neutral without tripping the live of the appliance that share the neutral is dangerous.

All the neutral that share it will actually become live which is more dangerous than before.

And since you have 3 phase electric supply , kaboom if different phase mix into neutral line which lost the link to the main neutral link.
*
Duly noted Sir! smile.gif
dv7.sun
post Jan 17 2019, 01:10 PM

New Member
*
Junior Member
7 posts

Joined: Nov 2015
QUOTE(stevie8 @ Oct 9 2013, 10:32 PM)
My house MCB most of it harden already, stuck, so difficult to pull down or push up. My electrician advised me to change all even though some are still good. And he suggested all change to 32A. I have 10, 20 and 32A. I am worry about his advice to change all to 32a and if the cable/wire can take load and what is the danger of doing so.

It is time to get some advice from others like you and be sure and if I can diy or just let him do it. See picture of my DB and the 3 types of MCB.

[attachmentid=3668036]

[attachmentid=3668038]  [attachmentid=3668040]
*
please report to ST about this action from your electrician...

https://aduan.st.gov.my

mcb need calculation before installation... it depends your load and cable size selection... purpose for the mcb is safety... overload and shock... please do not consult the decision if you not confident with your electrician... it might kill you.. safy first

IceBikers
post Jan 17 2019, 01:59 PM

Enthusiast
*****
Senior Member
957 posts

Joined: Jan 2003


32A not suitable for residence, unless for known high power electrical device
20A for aircond (max 2 HP im not sure bout this) / water heater
16A for plug
10A for light n fan
( I may be wrong, but it is close, however c32 really not fit)

32A mayb hardly trip if anything happen.

example using 16A, if the device overload more than 16A, it will trip for safety. but if using 32A, it won;t trip and perhaps situation may gone bad like Device explode or fire.

This post has been edited by IceBikers: Jan 17 2019, 10:26 PM
tlcm5229
post Mar 22 2020, 11:07 PM

Getting Started
**
Junior Member
56 posts

Joined: Jan 2017
Any experience and trustable electrical technician? One of water heater breaker trip? My house in Puchong.
Please PM me if you have any recommendation.
dv7.sun
post Dec 31 2020, 04:50 PM

New Member
*
Junior Member
7 posts

Joined: Nov 2015
QUOTE(weikee @ Oct 9 2013, 10:54 PM)
Your electrician want you to change house is it? All 32Amp, if wires are 1.5mm, use until wires burn the MCB won't trip. Usually they will put 20A for socket, and some will use 32A for a/c and heater, but 20A is good enough because 2.5mm can't supply 32A load for long period, and now a/c don't have such high spike.

Light, use back 6A or 10A.

Best check the old MCB, and do direct replace.
*
please report this technician to https://www.st.gov.my/


https://www.st.gov.my/en/microsites/index/4/8


this technician not follow IEC
Momo33
post Dec 31 2020, 05:03 PM

Regular
******
Senior Member
1,353 posts

Joined: Oct 2019
QUOTE(dv7.sun @ Dec 31 2020, 05:50 PM)
please report this technician to https://www.st.gov.my/
https://www.st.gov.my/en/microsites/index/4/8
this technician not follow IEC
*
yes...
i have seen too many electrician screwing up your house with wrong replacement devices and
wrong advise...
just read and follow ST recommendations is best and advise by K experts here ... thumbsup.gif




kirlcheah
post Dec 31 2020, 11:07 PM

Getting Started
**
Junior Member
60 posts

Joined: Apr 2005


QUOTE(beLIEve @ May 11 2017, 02:26 AM)
hmmmm that's where my concern is. Or probably it's unwarranted.

Type C will only trip at 5x its rated current. If my understanding is correct, there'll be no trips below 5x. On a 20A Type C MCB, it means that 99.9999A can flow through the cable without it tripping. If it heats up the cables long enough, fire or short circuit.

Of course, knowledgeable people know not to overload any particular circuit, but we can't stop anyone from doing so.

This was the reason why my friend said there's no point protecting the RCCB with an MCB. I guess there's no harm trying though smile.gif
I don't think I've much choice. Seems like it's our norm in this country to compromise safety for convenience. When I goto shops for 10mA-30mA RCCB, they'll always tell me "don't buy this, always trip". I guess the same applies to MCB, so no Type B for the wicked.
*
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....

This post has been edited by kirlcheah: Dec 31 2020, 11:09 PM
beLIEve
post Jan 1 2021, 08:44 AM

三軍都督
*******
Senior Member
6,977 posts

Joined: Jan 2005


QUOTE(kirlcheah @ Dec 31 2020, 11:07 PM)
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....
*
My Hager 30mA never trip on lightning, without arrestors. Perhaps a good brand makes a difference? Besides, shouldn't an RCCB trip on Amp leak rather than Voltage surge?

Sometimes don't get to choose. Most people rely on contractors.
ceo684
post Jan 1 2021, 10:56 PM

Component Burner
********
All Stars
11,545 posts

Joined: Jan 2003
From: Klang/Subang



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.
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 rclxub.gif 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 rclxub.gif

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.

Attached Image

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 rclxub.gif seems like they just wanna sell you another piece of RCD rclxub.gif The ST spec for Water Heater requiring 10mA RCD is the only good part. thumbup.gif

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
ceo684
post Jan 1 2021, 11:04 PM

Component Burner
********
All Stars
11,545 posts

Joined: Jan 2003
From: Klang/Subang



QUOTE(beLIEve @ Jan 1 2021, 08:44 AM)
My Hager 30mA never trip on lightning, without arrestors. Perhaps a good brand makes a difference? Besides, shouldn't an RCCB trip on Amp leak rather than Voltage surge?

Sometimes don't get to choose. Most people rely on contractors.
*
RCD/RCCB is measuring current delta (difference between in and out).
Voltage doesn't cause it to trip. The current IN on live must equal the current OUT up to the specified delta allowed (10mA or 30mA or 100mA or 300mA).
Not good to have >30mA for residential application if you value your life.
100/300mA only for commercial/light industrial use with big motor/heavy machinery.

Voltage wise we're talking about SPD (lightning surge protection) Type2.. where there are ciplak MOV types sold for 20-30 bucks made in china unknown brands to about 2xx for a single phase Hager/Schneider, and about 400-500 for 3ph+N for ABB/Hager/Schneider. It is easier to find the 3P+N type than the single phase 1P+N SPD.
ceo684
post Jan 1 2021, 11:19 PM

Component Burner
********
All Stars
11,545 posts

Joined: Jan 2003
From: Klang/Subang



QUOTE(beLIEve @ May 10 2017, 03:06 PM)
Back to the original topic.

Anyone here use MCB Type B at home? Seems like everyone is using Type C, but of course, most were probably installed by developers. Forgotten to find out if Pasar Road is selling Type B. The last time I bought, I didn't know the existence of Types B C D, they just gave me a Type C.
*
Due to the prohibitive cost of purchasing other B curve MCB (from RS) I just use B16 x2 for my WH circuits on Siemens 5SJ series cos they were relatively affordable at 15 bucks each. The rest cost one extra digit per MCB :x
cfc
post Jun 4 2022, 11:24 PM

Casual
***
Junior Member
438 posts

Joined: Apr 2005
QUOTE(ceo684 @ Jan 1 2021, 11:19 PM)
Due to the prohibitive cost of purchasing other B curve MCB (from RS) I just use B16 x2 for my WH circuits on Siemens 5SJ series cos they were relatively affordable at 15 bucks each. The rest cost one extra digit per MCB :x
*
Hi ceo64, mind share where to get the 5sj .. seems Google malaysia search didn't give much result
ceo684
post Jun 5 2022, 08:08 AM

Component Burner
********
All Stars
11,545 posts

Joined: Jan 2003
From: Klang/Subang



QUOTE(cfc @ Jun 4 2022, 11:24 PM)
Hi ceo64, mind share where to get the 5sj .. seems Google malaysia search didn't give much result
*
RS component/element14
Or import from SG lah, in SG whole DB box use B curve
cfc
post Jun 5 2022, 09:47 AM

Casual
***
Junior Member
438 posts

Joined: Apr 2005
Thanks ceo684
One question , for old house with old wiring , will it have frequent trip if I use 30mA RCD ? I know will have voltage drop for old wiring but for current , total In=total Out + some minor leakge current right , it should not matter if use 30mA for old house right.

Just check, my old house has really old stuff, don even know what the black color stuff is.
The DB box just have mcb, does not have any rcd, any idea which type (40A,63A) i should buy ?
my intention is to improve the house electrical safety , probably need to have a enclose case for that rccb too
any recommendation
» Click to show Spoiler - click again to hide... «


and also planning to replace the elcb for the WH to mcb + rccb
just buy 3 way DB that fit + 20A MCB + ABB F202 RCCB 25A 10mA will do right
need to make sure technician use 4mm2 cable during installation too ?
» Click to show Spoiler - click again to hide... «


This post has been edited by cfc: Jun 5 2022, 01:08 PM
mushigen
post Apr 11 2023, 11:00 AM

Look at all my stars!!
*******
Senior Member
4,502 posts

Joined: Jul 2010


Apologies for necroing this old but useful thread.

My existing WH is only protected by 18mm-width C20 MCB.

May I know:
1) this 18mm MCB is 1P+N, correct?
2) is this 1P+N mcb safe compared to 2P MCB?
3) if I add RCCB, do I use 1P+N or 2P RCCB?

TQVM
Ichighost
post Apr 12 2023, 11:07 AM

Casual
***
Junior Member
354 posts

Joined: Aug 2008
From: Oxpod



guys help take a look.

red-C10, blue C-20 and bottom most row C-32

C-32 i use for AC, Water Heater and Oven..using 4mm wire for all C-32.

user posted image
ceo684
post Apr 13 2023, 12:07 AM

Component Burner
********
All Stars
11,545 posts

Joined: Jan 2003
From: Klang/Subang



QUOTE(Ichighost @ Apr 12 2023, 11:07 AM)
guys help take a look.

red-C10, blue C-20 and bottom most row C-32

C-32 i use for AC, Water Heater and Oven..using 4mm wire for all C-32.

user posted image
*
where is the 10mA RCD for WH?

7 Pages « < 4 5 6 7 >Top
 

Change to:
| Lo-Fi Version
0.0227sec    0.15    6 queries    GZIP Disabled
Time is now: 29th March 2024 - 05:53 AM