Anyone knows how to size MCB of our home?

Got B,C,D type and different Amperage. How and what to choose?

Bro, if you are not sure please get engage the help from a professional electrician. In the event of overload, fire may occur thus handle with care.

This post has been edited by Xccess: Oct 9 2013, 02:40 PM

varies on electrical appliances, lights usually fitted with 6 ~ 10A, airconditioner and fridge to 30A ...

Common is 6, 10, and 15.

30A make sure you have thick cables minimal 4mm.

How to know 4mm, xmm? Some cable got 3 wires, some 1 wire, etc.

What mm for which Am rating?

Thanks

Actually, why do you post this question?

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.

all change to 32? what for

if the device only suppose to run 5A, and connect to a 8A breaker. anything more than 8 it will trip to protect the device

unless you expect it to shoot up to 32, no point to up the amp by so much. 100 percent still reasonable, few hundred

First thing you need to do is terminate your electrician....change all to 32A???


The big one with black handle is the Main Switch - If you ON/OFF this, it will ON/OFF whole house
The blue handle is the ELCB (Earth Leakage Circuit Breaker) - This is the protective device to protect your electrical system if there is a current leakage.
The other are MCB (Miniature Circuit Breaker) - This is the circuit breaker of each wiring circuit.

My suggestion....replace according to existing rating.....


This post has been edited by ezzone: Oct 9 2013, 10:58 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.

Thanks for the replies.

But the problem is few socket/power point to one MCB. So, if on all together total load could be more than 20A.

Let me check one by one and post here again.

This is not the original, he changed it 12 yrs ago when i reno my house so direct replace also may not be correct.

I will test out all how it is all connected how the MCB are shared and post the table here for your further advice. Now at night cannot test, cannot see in the dark.

Also, that is why i am asking about the wire, how to identify the wire rating.

This post has been edited by stevie8: Oct 9 2013, 11:04 PM

1) The solution to this particular problem is to add more MCB and split some of the socket to the extra MCB.

2) As others have mentioned using 32A MCB with writing only meant for 10, 15 or 20A MCB will lead to fire when there is an overload.

3) fire you electrician and get one that gives good advice.

Not easy to guide you identify wire type. Best go to the electric shop ask sample. Alternative, take out your power point faceplate see the wire, hope your contractor use the correct wire size.

If you share few load into one MCB and use over 15amp load, long run if the 2.5mm cable don't burn it will get harden and trip frequent because cable can be crack.

You better get a qualified electrician - make sure he is registered with TNB before you engage. Wire-cable thickness is very important ... if the load more than wire can handle then it will overload which leads to wire becomes heated up which leads to electrical fire.

Each wall power socket should not be more than 13A which means your fuse should be 15A. And depending on how your electrician wired up your sockets previously ... some electricians do short cut ... they put multiple wall socket on one wire example one room you ask 3 sockets ... that may be shared with 1 wire 1 MCB ... thus it is no better than an extension bar ... maximum load combined is only 13A.

Kitchen appliances such fridge, washing machines, microwave, electric stove, etc. usually will require its own dedicated socket and MCB ... that would be around 20A each. This especially true if you use very old appliances. New modern appliances nowadays use a lot smaller amps - so a standard 13A can support.

You better check your appliance power draw requirements and count ... to be safe make sure total amp to 1 wall socket is no more than 13A. If you are overloading ... you have inefficient electric wiring which leads to high power loss which leads to a higher power bill.

So when it comes to electric wiring ... don't play-play ... be penny wise pound foolish.

Hope that helps.

This post has been edited by amberglow: Oct 10 2013, 10:41 AM

Can you advise what mm wire is for what amp MCB?

Guys,

This is the power table of my house (see attached files).

As you can see from the picture post earlier, there is no more space for MCB, how to add?

Bro, a word of advice, please get the help of a certified electrician. I used to work as a electrician many years ago when I was much younger, even with a certain level of experience, I won't touch the electrical box let alone changing of ELCB and ECB.

Please take note there's live wire in it unless you shut off from the main electrical board outside your unit. Stay safe.

Lighting Load
6-10A (cable use 1.5mm)

Power Load
20A -30A (cable radial or ring circuit)

Not many use ring circuit.

Thanks for your advise, this thing cannot DIY, too dangerous, evenh though I know got to pull out the big black fuse from outside at the meter. There are just too many wires in the DB, once take out the MCB got to mark which pair in the circuit. And if cannot finish work in one day, whole house got no light. Fridge has to be empty otherwise foods go bad.

Thanks....but how this thing look like? What is cable radial or ring circuit?

You can't see it by visual inspection. Ring circuit is from MCB to socket/power point and back to MCB. This is good design circuit but not common practice here.

Any electrician real good and qualified one to recommend?

How man? The existing DB Box is full and I have so many power points and dont know how it was connected if one wire shares many points.

Sorry I don't. I'm also looking for one .

You can get electrician to add an extra sub-board, either next to the existing one or some other place in your house then run 60A or 100A cable from that sub-DB back to your main DB.

But I expect that will cost something like RM1-2k including hardware (RM700-1200).

Cheers.

Bro, please check your PM.

Cost is not so much of a problem. The problem is under the existing box below are a row of switches sure got wire running in the wall.

Also, the wires now terminated at the DB box and how to connect to another place without major re-wiring? Even next to it still need to connect and lengthen the wire one by one?

This time i want to make sure i know what is to be done before getting electrician to do what he wants or easy cincai job.

Thanks. Can show a picture of your DB kah? Just want to know how many MCB you have and how complicated it is.

Ok wait, I try to take a photo then post it here.

Here you go.

Yeap, sorry to say it wont be a simple job.

If you have usstairs and downstairs then most of the wires will run from upstairs to downstairs at the same place, somewhere near the DB, most likeley just above it.

Then the easiest solution is to put a sub-BD upstairs near that common location and connect all those wires from upstairs into that DB, then run one big wire downstairs to the main DB. now your upstairs sub-DB should have several spare CB slot, and you will have freed up several CB slot in the downstairs DB. then can add in extra DB as required.

In Australia most of our internal and even most external walls are cavity walls, so its very easy to run extra wires.

Here in Malaysia the wires usually plastered into the brick wall so have to hack the wall to run new wires. If your super lucky the electrician will have placed some conduit in the birck/concrete wall and you can pull a new wire through that without hacking the wall, but from what ive seen that is very very very rare case in Malaysia.

Cheers

Thanks bro.

Look like you got no 32A. Mine many of it and I think the wire cannot take load of 32A. Before it trips the wire burned first.

By the way your RCCB is 0.3A (300mA). Mine is 0.1A more sensitive.

Cost really depend on the aesthetic, it need to be hack and conceal again. When I renovate my house, I insist minimal looping, and identify every single point that go direct. I have 2 DB Box, one per floor, even separate the ELCB.

My ground floor



My first floor

Good idea to have the sub DB upstairs. But I have to find from photos taken last time. Below pic is the massive wires at DB photo taken during reno 12 yrs ago.


This is where the wire from G floor to 1st floor and up to ceiling, i think. Got to go up to ceiling to check this week end.


As you can see no conduit in wall. Conduit only on those above plaster ceiling. So have to drill a hole thru the 1st flr slap down to plaster ceiling for the thick cable

http://en.wikipedia.org/wiki/American_wire_gauge

Here is the photo taken from ground floor. The wire from DB far end near door, drilled thru the beam and up to 1st floor. But only for new cable. The old cable not sure how it goes up.


This post has been edited by stevie8: Oct 10 2013, 09:12 PM

Just for comparison purposes here is my current DB. Its quite small, but its only for a 3 bedroom 1200sqft Condo with only 4 AC, 3 of which are hardly ever used.

There are 12 CB.

5 pcs 32 A
4 pcs 20A
and
3 pcs 6 A

the RCB is 0.3A

and the Main CB is only 32A.

I once tried to map out which lights and power sockets got to which CB but i gave up after only a few as it didnt make much sense. In particular some CB had both Lights and power socket on the the same CB, which is a big NO-NO is Oz but not sure about the wiring rules here.

My the power sockets for the Kitchen, laundry and common bathroom also also seem to be on one CB, since i have tripped it a few times when I have I had the washing machine, kettle, rice cooker and someone showering at the same time.


Cheers


Attached thumbnail(s)

Wow...nice.

Can't understand the table. mine showing me which are for 10A, 20A and 32A from the table?

My original DB also look like this.

It show the cable thickness and its properties. A more layman site http://www.epanorama.net/index.php?index=calc_cable It give you very general guideline if room temperature are 20c, if you have bad quality cable or long run cable the guideline won't apply.

This post has been edited by weikee: Oct 10 2013, 09:35 PM

Look at the Column called "NEC copper wire ampacity with 60/75/90 °C insulation (A)[7]"

NEC in USA means National Electrical Code which is the rules for wiring etc.

This Column has 3 numbers which correspond respectively to whether the wire has 60 or 75 or 90 Deg C insulation.

In that column find the maximum Amps you need to carry, and then look across to the the Wire Diameter in mm2.

BTW unless you are sure best to always assume your wire is the lowest rated insulation ie 60degC

eg Lets say you want to caryy 32A, there is no 32 A for 60degC, only 30 or 40 A, so select 40A then look across and you will see you need 8.37mm2 wire.

Now 8.37mm2 wire sounds a little bit big to me for 32 A, which I seem to recall (assuming my memory is working correctly) 32A usually needs about 4mm2. Now from the table you can see that 4.17mm2 wire can carry something between 30 and 40 A if it is 90deg C insulated (but like i said always better to oversize wires and be safe than sorry).

BTW I'm an Aerospace, Mechanical and Industrial Engineer, NOT an Electrical Engineer so take the about as friendly advice only. Best to consult an Electrical Engineer or licensed Electrician.

Cheers

Weikee, Sydneguy,

Tq very much. Now I am somewhere to it already.

I am not trying to master. Just want to know if the existing wire is safe and use the right CB for the circuit when I get my electrician to replace and add the CBs. Not just blindly follow what he says. I should have that many CBs as what Weikee has with 2 DBs.

The idea of having 2 DBs is great. I just need to locate where the original developer wires supply to 1st floor. I think it should be somewhere at the ceiling where there is a bunch of wire out from one of a side wall. There will be some hacking but it is ok.

1 Lowyat forumer problem solved, 23,494,985 to go

Just to confirm one more question.

Diagram below refers:


In the radial circuit as circled in red. The circuit is protected by a 20a CB.

Question:

Am I right to say the amperage of the wire(denoted in red) it carries in the radial circuit is the sum of all the 10 power points? If each point consuming 1a, the total amperage of the "red" wire is 10a?

Similarly, The "green colour" wire is the sum of 7,8,9 and 10?

Yes, but 10 is way too much. If the circuit break for whatever reason you lost 10 points. And if got flyback say from lighting strik to one equipment you may loose all the connected equipment.

One more question comes to mind. Look like never ending...

If I get to locate the bunch of wires run up to the first floor and cut them and fix a new DB at the 1st floor, I then need to run a thick cable from the new DB to the main DB at the ground floor right?

Question:

Instead of pulling a new thick cable (live, neutral and earth), can I twist a few or all of the existing "cut" cables (become a big thick cable) that I cut (for making the new DB) which connect down to the ground floor DB, same twist them together? See drawing below:



This post has been edited by stevie8: Oct 11 2013, 12:37 PM

Ewwww ... really bad design .. your power sockets are no better than a RM30 extension bar since they all share the same fuse. One blow all blow ... and you have a high chance of overloading unless you are consciously remembering how many devices you are putting on that circuit.

This is not my house wiring la. This is from wikipedia just use it to illustrating and asking a question.

You could but its not really the right way to do it for a few reasons.

1) after cutting the old wires probably be to short by a few inches to go from Main DB to sub-Db. remember you want to cut the upstairs wires from sockets a bit longer so its easy to connect into Sub-DB and you are not trying to stretch wires.

2) joined parallel wires don't really have the same capacity in practice as they do in theory. Also its easy for 1 or 2 wires of a twisted set to come loose from the crew point, then youve got loose wires and reduced capacity and remaining wires are now free to come loose also.

3) It will be very hard to join those several wires into the DB and sub Db.

4) its just plain messy.

5) AFAIK its probably against the wiring rules/codes.

6) the 2-3 mtrs of big wire from sub to main will only cost less than RM50, so its not a bifg cost

the only real reason to do what you suggested is to save $ and time inconvenience on hacking and plaster back, but this is easly out voted by reasons 1-5 above.


Cheers

Add on to that; How sure the existing cables not tap to other place? If it was tapped you risk sending live current to unknown place.

Thanks for the input. You got me, "the only real reason to do what you suggested is to save $ and time inconvenience on hacking and plaster back"

Anyway, hacking is unavoidable for the installation of sub DB where I need to hack out the cable long enough to get all of them one by one into the MCBs in the sub DB. The problem is to hack thru the slab and beam. I do not want another hole thru the beam which is at the middle of the house, it only weaken the beam.

I just need to find two 4mm wires each and twist them together which will support 60A, right? Below is the potential load up-stair:

1 x 2 1/2 hp aircond
2 x 1 hp aircond
1 x iron
5 x fans (not on when use aircond)
30 x downlight, wall light and table lamp.
1 x vacuum cleaner (not use when ironing), my wife cannot be doing 2 things at a time
Many power sockets but seldom use other than mentioned above for ironing, vacuuming, also for charging handphone, hair dryer, no water heater (I use solar heater), TV, Audio, PS2 games.

Therefore, one 4mm for 32A could be enough, but 2 x 4mm definitely more than enough. Then need to connect 2 x 4mm wire to one 8mm wire to the sub-DB.

What do you think if I use lead soldering to join the 2 4mm wire together instead of twisting them together for terminating at the sub-DB and the down stair DB? How good is the lead joint conducting electricity compare to bear copper wire?

Cheers

You old house wiring come with 4mm wiring too?

hmmm.... thanks, have to be super careful. I think the way to find out is to switch off the MCB how it is linked and double check.

Not sure, I did not take notice of the old DB before the reno if there was any 32A MCB. But during reno the electrician could have use 4 mm since he put so many 32A MCBs.

This post has been edited by stevie8: Oct 11 2013, 03:06 PM

OK, found it. Of the 32A MCBs, the no. 4,5 and 6 are used only for 1st floor. These could be 4mm wires not shared else where with down stair.

Don't assume, need to confirm. Put 32amp some can put 2.5mm because then amps for starting load only.

Once you pull all the old wires that went upstairs out there will be a big hole in the floor/beam for you to put the new thick wire through , Problem Solved.

1. There are floor tiles at first floor, the hole could have been sealed during tiling.
2. Plaster ceiling at ground ceiling where the cables going thru the beam except that the hole at the beam was not sealed.
3. Then on top of the main DB where the new thick cable coming down from plaster ceiling the wall is concealed with many wires from all over the house, cannot hack but to run externally with plastic casing.

3 obstacles that is why am considering using the existing cables, otherwise, I will not hesitate using one thick cable. Anyway got to consult electrician and plaster ceiling guy and tile I do not think can find same pattern tile. 12 yrs already.

This post has been edited by stevie8: Oct 11 2013, 08:42 PM

Hello. I have a situation where a fuse keep kicking back. The pic of the db is attached. The one that always kicking back is the 20A one. So the question is, can I change the fuse directly or i should change the wire first to 4mm?


Current wire size is 1.5mm. I think.


Attached thumbnail(s)

B, C, D types are for the inrush current.. Domestic uses type B

Ampere rating are for current overload protection of the cable. Size the amps according to the cabl's current carrying capacity..

Scroll to the btm of the page, the link at the btm.. Read it.
Suruhanjaya Tenaga - Guidelines for Electrical Wiring in Residential Building 2008

Is this a new installation and is it a new mcb?
If yes then its probably this circuit is overloaded causing a thermal trip.. Get a clamp ammeter and cheack the load and compare it to the mcb's rating.. If overloaded then remove part of the load to another circuit (If it's more that one load on the circuit)

If no (meaning it was working well previously) then listen carefully to this particular mcb.. If you hear small crackling sounds before tripping then replace the mcb. The mcb has pitted contacts, that means the contact area has reduced to the point where it itself causes the thermal overload.. The device is faulty..

You only replace wiring if the insulation is damaged and you test with an insulation tester (Meggar).. Hire an electrician for this.. He has the equipment and competency to use it.. You cannot use a multimeter..

This picture shows a Three phase Distribution board (DB)..

It's protection device ia a 4 pole Residual Current device (the one with the yellow trip button)

The RCD is for 3 phases that's 100mA trip per phase..

Whether yours (0.1A) more sensitive depends if you have 3 Phase supply ..

meaning is your RCCB 2P or 4P?

If 2P then i think it is not more sensitive..

Hi. It was an old thing. It happened whether i switch on my computer or nothing while I'm not switch anything at all. It kicked back like ikut suka dia. So my plan maybe upgrading the 20A fuse by changing it to 32A fuse. Is it possible the problem will still occur after changing the fuse directly? Also that fuse goes to one 3-pin point and then loop for two more 3 pin point outside the room for washing machine use.

get a new one. this time dun buy fanban multi9

the normal washing machine should be fine, as long as you dont use iron and hairdryer all at the same time.
as said, most likely its a busted mcb. just change but change to better brand.

Firstly, use the correct terms for the components, it helps avoid confusion..

A fuse cannot kick back.. It is a fusible link.. It blows (meaning gets hot, melts thus disconnect) when over rated current flows through..
A miniature circuit breaker (mcb) trips (meaning there's a bimetal contact which trips a spring) when over rated current flows ..
You replace a fuse.. You reset an mcb (only replace if faulty)..


Yes, it is possible.. This is a forum and I'm just giving my opinion. You need an actual competent person to repair it.. (An electrician)

However the fuse or mcb function is to protect the wire.. It blows/trips before the wire gets hot.. A 1.5mm wire is rated at 23Amps..

A 32A fuse/mcb cannot protect a 1.5mm wire.. The wire will melt and burn anything combustible close to it..
It might burn down your house.. Pls understand your risk..

Hire an electrician if you don't know what I'm talking about.. It will save you more..

ok..

Standard domestic wiring regulation requires you use 2.5mm2 or higher size wire for sockets..

When new the metal within the wire is pure .. An older wire oxidizes and its insulation degrades.. It cannot carry rated current and heats up when over current..

Regulation states you must completely rewire after 30 years.. I rewired my house after 20 years.. It's my insurance..

Good luck..

This post has been edited by Richard: May 10 2016, 03:42 AM

Another question. Is there any way for me to determine which wire go to that particular point etc.? I mean if i want to change the whole box with the fuse everything. So that i can reconnect the wire to the box correctly. 1 seperate fuse for a/c etc.

Yes.. Switch off all your miniature circuit breakers (mcb)..

Standard wiring mcb's all type B's except motor (if nuisance tripping then use type C or D for higher inrush(start) current)
-------------------------------------------------------------------------------------
6A & 10A are lighting mcb's
16A & 20A are socket/aircon/water heater mcb's
32A are cooker/large freezer/3HP & above motor mcb's

- Switch on only one mcb
- Visually check which one has power and record on the mcb
- Switch off
- Repeat next mcb..

Seriously..? I myself am certified with ST but i get an electrician to do the work.. For me it's a matter of cost and speed.. I can talk the talk but crawl the walk if you get what I mean..

For you I think it will be an additional safety issue.. Wiring a whole house with 20-40 points is not an amateur DIY..
One point is ok.. Not whole house.. you're crazy to think you can do it..

I spoke to a friend and it appears that there is more to just the amperage on the MCB vs the amount of current you need to size an MCB. If the amount of current is below the MCB's rating multiplied by the value of its type, there'll no trip. In an overcurrent situation, most likely your electrical/electronic device will get fried (it's gotta be already faulty to draw excessive current) before your wire if you're lucky.

To size it, you'll need to know all the resistance involved (wire, devices, earth loop, inrush current). Not sure how many have the equipment to perform these tests?

Anyway, just to share.

http://www.studyelectrical.com/2014/07/min...tic-curves.html



http://www.theiet.org/forums/forum/message...&threadid=32143



The reason I'm researching this is because I have a neighbor who had his concealed wire shorted permanently, something I'd rather avoid.

This post has been edited by beLIEve: May 6 2017, 12:40 AM

Very detailed explanation : http://www.kevinboone.net/cableselection_web.html

To avoid that, any long term high current usages better direct from MCB with 4mm2 cables. And reduce tapping for extra points.

wise words, bro weikee. I think that's why the developer gave 4mm2 wires for room aircond despite room airconds are likely 1HP.

My neighbor's house was rented out. No one really knew how that socket was used as he only got back his house recently. It was looped alright. From MCB to 3 sockets. The last point was the one that fried.

I'm installing some new points for my own house. Will be using 4mm2 to minimize the melting problem, regardless of how long I use the current. Price does not differ a lot vs 2.5mm2 when I buy in rolls. The last time I paid for wiring, I was "convinced" that their 1.0mm2 (yes, I read it on the wire several times because I thought I misread it) 3cores is good enough for 2HP aircond. 1 month warranty woh.

BTW, I've read a lot of your useful responses here when I was searching for RCCB. Pleased to meet you, finally. Speaking of RCCB, another neighbor insisted that MCB will trip when there is a current leak when I tipped him about the 10mA RCCB for heater. I guess it would, if the leakage goes beyond the MCB rating x Type.

This post has been edited by beLIEve: May 8 2017, 05:10 AM

1mm2 should be ban from using as outlet point. Maybe just a single light point is ok.

Wires problem usually won't happen so fast. Maybe only 1-2 years after usages. Unless of course it was intended overload.

ELCB/RCCB will trip only beyond the threshold level, more sensitive will be more expensive. If you have 10mA RCCB, and DB installed with 30mA. In scenario when leaking say is 15mA, the water heater RCCD will trip but not the DB side RCCD.

That's why he confidently gave 1 month warranty. I always consult my friend before agreeing to all the deals offered by contractors. When problem occurs, can make money pulling new wires again.

Referring to RCCB, yes, after so much research, that's what I learned. Also read that some will trip at 50% of the value. Didn't drill too much into that.

Let me ask you this, since you're a 高人. Which is better? 10mA RCCB between MCB and water heater, or MCB between RCCB and water heater? My friend recommended the latter, but I went for the former after some research. It's sort of whether I want the MCB to protect RCCB from potential overcurrent damages, or RCCB to protect MCB from leakages. I'm protecting the RCCB because it's much more expensive. He said RCCB will not break, though I wonder what will happen when 100A flows through a 25A RCCB.

Don't look me so up. I just speak from my general knowledge.

If you plan to do "MCB between RCCB and water heater", unless you can identify the water heater neutral wires at the DB box if can't you will not have a balance current and it will always trip.

You use a water heater for hot water..

You use a 10mA RCD to protect your life from electrocution from the water heater..

Why would you value a 10mA RCD higher than life?

Edit * Watch this youtube video.. It is good .. https://www.youtube.com/watch?v=A5HuPol99sU

I also find it pretty funny ..

This post has been edited by Richard: May 8 2017, 09:58 PM

I'm very short only. That's why have to look up on you

Actually, I thought as long as I add an RCCB, I need to identify the neutral wire no?

My original setup based on my friend's advice :
Live busbar --- wire --- RCCB Live Top --- RCCB Live Bottom --- MCB Bottom --- MCB Top --- Water Heater Live
Water Heater Neutral --- RCCB Neutral Bottom --- RCCB Neutral Top --- Neutral bar

New setup :
Live busbar --- wire --- MCB bottom --- MCB Top --- RCCB Live Top --- RCCB Live Bottom --- Water Heater Live
Water Heater Neutral --- RCCB Neutral Bottom --- RCCB Neutral Top --- Neutral bar

Yes I managed to identify the neutral wire. Small apartment, and developer was generous enough to use a 4mm. Only 2 of these.


Bro, did you misunderstand my posts? Or you see something wrong with my setup having MCB before RCCB?

Thanks for your responses.

I might have actually ... when you typed " I'm protecting the RCCB because it's much more expensive." ..

My mistake..

Your setup is a standard arrangement i.e. The RCCB (or RCD) doing the protection of life, while the MCB protection for the property (cable, RCD & load)..

It's good..

thanks bro Richard

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.

I only experience seeing type C in the market..

Physically the difference is nominal (I.e. in name only), as it deals with the breaking capacity of the breaker.. thus the physical characteristics of the spring.. you would need a department like SIRIM to be able to tell the difference..

You and me, we take and accept what is available..

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

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.

Some of the rare or hard to find items, i usually pay a bit more and buy at element14, The B curved should be available there

http://my.element14.com/abb/s201mb16/mcb-1...urve/dp/1775068

Thanks bro weikee.

Yes, I found it there and my friend is using element14 exactly as you - for rare items. These are made in Europe too Costs 8x more though.

http://my.rs-online.com/web/c/automation-c...archTerm=S201b2 seems cheaper than element14. I don't know who will do the customs clearance and not sure if SIRIM approval is needed.

Edit : Ok, my friend say all the clearance will be handled by element14.

This post has been edited by beLIEve: May 11 2017, 12:13 PM

Correction..

On a 20A Type C MCB, Once there is an overload current meaning more than 20A the breaker will trip .. There's a coil within which pulls in a metal piece (an electromagnet) which trips out the breaker..

Type B, C and D only refers to the inrush current .. produced by inductive lighting and motors.. The 5x is a transient (momentary or short time only) current during the start to enable starting torque(of a motor) or to jump a spark (of lights)..

Once the motor is running or the lamp is lit, the current goes back to rated normal..

A continuous flow of overload current (beyond 20A) will heat up a secondary part of the breaker (a bimetal strip)..

Your friend is misinformed .. A MCB protects against an overload (both magnetic and thermal type), a RCD protects against leakage current (below the rated) but will kill a person..

You need both devices in your DB, one to protect property, the other to protect life.. It is a mandatory (MUST HAVE) requirement..

For the secondary RCD at the water heater I believe it is only recommended not yet enforced by our Suruhanjaya Tenaga..

If you read the news then you know that people have died due to faulty electric water heaters .. 50mA AC Voltage over 5 secs will kill a fully grown 60kG human male..

You can google, read it up or ask any medically trained person.. The symptom is similar to a heart attack with burns at the contact areas..

Edit*

If the device keeps tripping then there is a leakage current, dirty equipment in a high humidity environment is the usual cause...

The dust settles on the live or Neutral wire and when wet will leak to a conductive cover tripping out the RCD..

You need to clean the electrical devices.. Wet dust can conduct electricity..

Edit**

Correction For the secondary 10mA trip RCD at the water heater.. It is a mandatory requirement by Suruhanjaya Tenaga..

This post has been edited by Richard: May 20 2017, 08:43 AM