1. Better upload as attachment rather than use the upload images function (too low res to see)

2. Water Heater RCD (one each per WH unit) From the pic, no 10mA RCD for water heater was installed. This is statutory requirement. For old installation nvm but since you gonna redo, follow current standard.

Why 10mA RCD needed for water heater?
Because wet floor has very nice conductivity for fault current to flow through human = https://www.malaymail.com/news/malaysia/202...c-shock/1896447

ELCB is dinosaur technology
ELCB in WH cannot, will not, and certainly DID NOT protect against leakage for current flowing through human. It only protect L-PE leak (ie equipment protection only). L-N or L to other E (wet floor) leakage is not included in ELCB scope.

How much does this RCD (or RCBO) cost?
RCD ABB (Italy) or Hager (France) ~168 (online)
RCBO Schneider (PRC) ~100-105 (online)
other china brand also around 70 bucks but this is one thing not to skimp on.. treat it as a one off life insurance.. without yearly renewal. Maybe change once per 20-30 years.


It only takes 0.05A of 230V to kill a person.


It is very easy for an electrician to hook up a 10mA RCD per water heater circuit. Just need to identify the dedicated N for that circuit and connect to RCD 10mA. RCD 10mA line side L feed from 20A (C20) MCB load side; RCD line side N connect to common neutral. It is not rocket science. But it will definitely protect you so you can buy me a coffee.

3. All the N is common neutral when it return to TNB so basically it is correct. Common neutral and common PE (Earth).
Individual circuit (dedicated neutral) is required for special case like 10mA water heater circuit.

4.ELCB is old dino tech, you mean RCD/RCCB for mains protection right?
Only one mains (whole house) 30mA RCD needed to cover the whole house.

Use 30mA (0.03A) as whole house RCD (aka RCCD/RCCB) will give you best life protection (in general) against any fault current - be it 13A socket or light circuit. And it serves as a useful secondary line of defense even if the 10mA failed to trip on time (for WH RCD).

Note:
Anything else (100mA / 0.1A) or (300mA/0.3A) gives fire protection for building protection only. These do NOT protect human life.
Coz if there is a fault, the human dieded 2x or 6x over.

5. As for the 18W lamps.. you will need 100 pcs of them to be equivalent to a single electric kettle. One ceiling fan only takes about 85W. All in all they are low loads.
I doubt you will exceed a total of 6A (1380W) even if whole house LED and ceiling fans are turned on simultaneously.

The ones to look out for are the big loads such as water heaters (3000W typical storage heater) or (3300W-3800W typical instant heater); kettles ~1800W;; rice cooker slow cooker; oven be it microwave or conventional; electric stove/hob/induction cooker/air fryer, basically in short heavy heating appliances do not do looping shortcut but run a dedicated line to DB box with proper MS2113 cables (mega kabel, caramay, fajar cable).

6. Choice of 3 units of single phase (2P RCDs) per red/yellow/blue phase or 1 single unit of a three phase (4P RCD).
Both are not wrong, the 3x of 2P RCD is more for "business continuity" in case red phase has fault, you can still operate things on the yellow and blue uninterrupted.
Whereas in the case of using 1x of 4P RCD, any one phase has fault detected, entire house goes dark until the fault situation is rectified.
Cost wise, one 4P RCD is still cheaper relatively as compared to three units of 2P RCDs.

This post has been edited by ceo684: Mar 4 2021, 12:38 AM

Yes, this is also important as phase-neutral is 230V
But phase to phase produces 415V fireworks show.

Why buy 2 piece of mains RCD 100mA and 30mA when the requirement is "maximum of 100mA tolerance" - i.e. NOT "equal to 100mA" or "not less than 100mA tolerance"?

A single 30mA for whole house is cheaper TCO and provide better life protection whilst still fully compliant to the regulation of "maximum of 100mA tolerance".

This post has been edited by ceo684: Mar 4 2021, 12:48 AM

Yeah the ideal is to use 3x 2P 30mA but only two concerns:
1. Cost-wise it is also OK to use 1x 4P 30mA if budget constraint cannot stretch. Protection wise, TS, is the same as long as all are 30mA.
-- The only diff is any fault will trip whole house, rather than just that one phase.

2. Physical limitation of DB box space. It looks kinda full at the moment.
-- 1x 4P use 4 module, vs 3x 2P use 6 module space.

3. 3-phase (4P SPD) for lightning protection
individual module replaceable type
-- CHNT (china brand) 40kA 4P ~423
-- ABB OVR-T2-3N-40-275PQS SURGE PROTECTIVE DEVICE [2CTB803973R1100] 40kA 4P ~480
-- SCHNEIDER A9L40600 iPRD40 MODULAR SURGE ARRESTER A9L40600 ~379

monobloc (use and throw as whole unit)
-- Hager SPD SPM440E 40KA 4P ~502
-- Schneider SPD A9L15688 40KA 4P ~490

useless toys:
those 30 dollar china SPD

This post has been edited by ceo684: Mar 4 2021, 01:10 AM

Sis actually.

1. What is the "MCB C20 WH"? is it different type of other MCB?
Standard C20 MCB.
WH denotes the one for WH circuit.

2. if I have 4 header, which mean I will need FOUR 10mA RCD?
Yes correct. WH 10mA RCD is per unit of WH. Each WH should be on its own dedicated circuit as one WH enough to use 15-17A nominal (WH is heavy appliance). Your 2.5mm cable only support 21A. And the 10mA RCD, only come (from branded mfg) up to 25A max current. In short, the standard cable sizing, the RCD current capacity (max 25A) all only suited for single unit WH as it is sensitive device (0.01A /10mA).
Whilst there are champions from china making 10mA RCD that can handle 40A I also dare not use.

3. The purpose of 10mA RCD is to trip when the heater leaking to our body? my current installation if leaking it won't trip?
Your current installation only trips at 300mA - by then, the human dieded 6 times over.
As the mains is 300mA, it allow 300mA leakage before it trip.
A human RIP at 50mA.


4. In short, I only need to have 10mA RCD in between the MCB and Header individually? Any other wiring need to be change/improve?
Yes, correct.
RCD is comparing input and output current difference. Input and output must = equal the same +/- RCD tolerance of say 10mA (0.01A).

Meaning, if WH input is 16A on L, at least 15.99A must return on WH output (N) else it has deemed to be lost somewhere.

Lost somewhere mean could be leaking through human.
So when the return not enough (<15.99) say only 11A return. The 4.99A cannot be lost, it mean it leak. As 4.99A far exceed the 0.01A allowed by 10mA RCD it will immediately trip.

MCB only consider single wire (L) amount of current passing through (short circuit prevention).
For a C20, meaning the speed limit is 20A.
Slight overload at 23A will trip the SLOW thermal overload after say 20 min.
Major overload at 100A will immediately trip the magnetic overload.

5. between I'm quite confusing are ELCB & RCCB the same? can you correct me if the naming in the image below wrong?
The difference is how and where they measure.
ELCB only detect earth current rise >0 leak (L to PE) leak on that appliance's earth. If it leak via anywhere else (L-N, or L-other PE eg wet floor, L-human) it will not bother. Hence in short I just say it protect that appliance only.

RCD because it constantly compare L input =N output + allowed tolerance (like 10.00A in on L, >9.99A must return as allowed tolerance is 0.01A for normal operation things like wire resistance that do NOT constitute a fault condition). It does not care where it leak through, RCD always compare in and out current so if it leak through any method (L-N, L-PE, L-other PE, L-human) it always trip.

Note: There is something called RCBO which do both function of MCB+RCD in one.


6. Appreciate if you can share the image of "MCB C20 WH" and 10mA RCD
MCB C20 is any usual C20 (20A MCB). WH is just designation for the WH circuit.

10mA RCD (must be used in conjunction together with C20 MCB) ie. add this along with MCB C20
ABB= https://www.lazada.com.my/products/abb-f202...i2IABn&search=1
Hager= https://www.lazada.com.my/products/hager-cc...l5n2dU&search=1
Schneider = https://www.lazada.com.my/products/schneide...8t5PsK&search=1

10mA RCBO = RCD+MCB in one package pao kah liao 2 function in one
Schneider RCBO https://www.lazada.com.my/products/schneide...PVCaV4&search=1
The drawback is, officially, their MCB is a C25 equivalent so you need to use with 4mm cable. As 2.5mm cable only good up to 21A rating.


First one from left is MCB 3P (3 pole) C63 (63A)
Second one is 4P RCD but this is 300mA. Only used in commercial/industrial where they use heavy motors. Not safe for residential and its against regulation, as the human has dieded 6x before this trips. (RCD/RCCB/RCCD = same function with diff name like zebra crossing=pedestrian crossing)
Third one is MCB 1P C10 (10A)

You will then ask, why do people still put the 300mA in residential?
Just to save the few bucks for more profit/lower tender cost

This post has been edited by ceo684: Mar 4 2021, 01:59 PM

1 size fit all, 30mA whole house for residential.
Lower mA is tighter tolerance/more sensitive for life protection.

I personally use one piece RCD for 3phase supply. In pic is 30mA 4P 40A (the incoming to the unit is only 10mm cable so 40A each phase). Yours is newer place on 16mm then the TNB is 63A, so you need a 63A 4P 30ma RCD.

Generally top tier RCD for MY market easily ibtainable are from these 3, ABB Hager Schneider.

This post has been edited by ceo684: Mar 4 2021, 03:58 PM


Attached thumbnail(s)

Ideally, per ST WH Guidelines page 14, the RCBO (25A 10mA) is connected after the mains RCD 30mA as well. So you will have the 30mA (whole house) as second level RCD protection.

As RCBO = MCB and RCD in one.
The RCBO unit can be installed like an MCB (replace the existing MCB with the RCBO in-situ).



The chain is only as strong as weakest link. All the way should be 4mm as the min cable size per ST guideline is 4mm for 3300-3800W WH.
Because typical load is around 15-17A.
Still can get away with 2.5mm if the 2.5mm cable is good quality (full copper and SIRIM and MS2113 certified) as the 2.5mm cable can take a 21A max load, but it is recommended to use 4mm if possible.

This post has been edited by ceo684: Mar 9 2021, 01:27 PM


Attached thumbnail(s)


Attached File(s)
 Guideline_for_The_Design_Installation_Inspection_Testing_Operation_and_Maintenance_of_Water_Heater_Systems__1_.pdf ( 4.49mb ) Number of downloads: 30

Yes correct recommended 4mm per ST spec. Regardless RCBO or RCD.

Per cable mfg spec 2.5mm is safe up to 24A single phase max load - http://www.megakabel.com.my/A-1.pdf


If cable is from proper mfg (u see there is MS2112-3, SIRIM QAS certified, and mfg name on the cable) then OK.


Between RCBO 25A 10mA & 20A 10mA, for safest choice 20A 10mA when using 2.5mm cable.
Whilst going 1A extra may not be much difference above the cable mfg spec but for insurance claim (in case fire occur) this kind of technicality can and will void the claim validity, so if on 2.5mm cable pls use a RCBO 20A 10mA,
or pair RCBO/RCD in conjunction with a 20A MCB (DB box space limitation).

This post has been edited by ceo684: Mar 9 2021, 03:48 PM

Hello, cannot use 4800W.

4800/230=20.8695652173913 A (21A for easy calculation)
by 80% derating factor (same as you don't redline your car every time) you should use cable that can support 26.25A ie minimum 4mm cable.

the minimum (as per ST spec) recommended is 4mm cable to use a 4800W heater (highlands model, usually from Pana or Hitachi).

In the market usually 3kw class is 3000W for storage, and 3300-3800W for instant WH. These are the recommended type (max power) for the 2.5mm cables typically installed.
Next step is 4800W.
Normally rare to find anything in between 3800 and 4800W.

If quality cable used.
If unknown/substandard cable.. insulation very thick, copper all substandard or adulterated so only 3kW class is safe option.

This post has been edited by ceo684: Mar 9 2021, 03:55 PM

Storage heater Rated Power : 3000W - Centon current series (QNQ RNQ SNQ)

Instant WH 3kw class = 3xxx W (typically 3300-3800W)
Older National/Pana is 3300W
Current series Pana 3600W
Current Toshiba 3800W

This post has been edited by ceo684: Mar 9 2021, 03:58 PM

Yes, correct, RCBO 20A 10ma.

Correct. Note that this RCBO is single direction connection to LINE/LOAD as top LINE/bottom LOAD ya.

Hi,
4200W / 230V = 18.26A


https://www.electrical-installation.org/enw...a_of_conductors
Per reference method B1 (single circuit, solid stranded cable enclosed in conduit) able to handle up to 21A with 2.5mm² cable.

This 21A is assuming that quality cable (eg Mega Kabel, Caramay, or any of the MCMA cartel members) is being used..
If elcheapo or fake cables - you might be running a risk that it is undersized for the load

Also the length should be kept to reasonable length.. if the cables are too long then voltage drop will be a problem as well
Because if effective voltage drops, the amps go up
e.g. 4200W / 200V = 21A.
So there is about a 10% reserve capacity of the cable current capacity with 2.5mm² cables.. insofar as ST regulations go, officially they recommend minimum of 4mm² so that no need to worry or calculate so deeply.

This post has been edited by ceo684: Apr 21 2021, 11:40 PM

Should be OK, they print their name and spec on the cable, there's an older SIRIM cert issued for MPC cable and it is not in the news for fake SIRIM certs
There are cases before - https://www.sirim-qas.com.my/forgery-on-license-no-pc000218/

How to identify a sub-standard cable (per https://www.st.gov.my/en/contents/files/dow...ble_testing.pdf )
1) Check and verify MARKINGS on Cable – shall be as per standard requirement
2) Check and verify APPROVAL / CERTIFICATION Mark/Label
3) Measure conductor resistance ( need to have a proper meter)
4) Measure size(s) • conductor • each strand ( and no of strands)
5) Check and verify copper content • normally by conductor resistance • weight the sample • Sometimes –by weighing the sample, with some experience, we can identify if the samples / weight of sample due to copper content or sheath of insulation

On the other hand w.r.t point no. 4 - there are also complaints on shopee that the cables are not as thick as they claim to be
https://shopee.com.my/MPC-2.5MM²-PVC-CABLE...2276.3417950523


This post has been edited by ceo684: Apr 22 2021, 11:24 PM

That really depends on the max current capacity of the cable vs MCB.
For good cable lets say its 2.5mm² max safe load 24A. Meaning when it overload it will get warmer and warmer (it will not instantly kaboom at 26A).
When fitted with C20 MCB, rated 20A.
Mini overload say 21A on C20 maybe take 20min to trip the thermal overload characteristic of MCB.
More overload say 22A on C20 maybe take 6min to trip thermal.
Add more overload say 25A on C20 maybe take 2 min to trip.
More serious overload say 30A on C20 maybe 10 sec to trip thermal.
Times are just pluck from the air.

Its just to illustrate the slow blow characteristic of MCB. It will trip before the cables get insanely hot. As its not a huge overload (that will trip magnetic) all these small overload are thermal trip based, the higher the degree of overload the faster it will trip. MCB close 1 eye for minor overloads, where 20.1A on C20 will also probably take forever to trip. Like overloading a lorry by 20kg..JPJ close one eye lah.

Risk of substandard cable..
What happens in the use of cheapo cables that are underspec, where a small overload like 26A (supposedly safe upto 24A, but cable actually only safe up to 15A) is that even in normal operation it is running warm and if it gets to 26A may be very hot but MCB thinks OK je..but normal timing of slow blow of MCB only work if good cable is used..for substandard cable the cable itself may run a risk of overheating and melting BEFORE the slow blow trips. As we also cannot tell how lousy a substandard cable is (obviously it will proclaim the best) this is a gamble that most of us dont want to take, hence we always spec quality cables, but customers some dont understand and want cheapest possible prices..it is very easy to buy cheap shit junk at half price, that we all know..but this is something we want to sleep peacefully at night.

In event of short circuit aka HUGE overload many tens or hundreds of amp pass thru suddenly, ie way way over 5 to 10 times the 20A C curve rating it will trip the magnetic part of MCB instantly.
If the lorry overloaded at 200% of course cannot close one eye..JPJ kasi saman and impound it!

To digress on the C curve of C20
MCB B curve instant magnetic trip between 3 to 5 times of rated full load current.meaning (3 to 5x) of 20A for a B20.
MCB C curve instant magnetic trip between 5 to 10 times of rated full load current. Meaning (5 to 10x) of 20A for a C20.

Malaysia is one of the funny places where B curve MCB is not common and C is plentiful. B curve already good enough for home use not to false/nuisance trip because..how many big motor or lathe machine or welding machine does one have AT HOME

In AU..B is commonly used for residential, i think same goes for UK.

https://www.se.com/au/en/faqs/FA290880/



This post has been edited by ceo684: Apr 27 2021, 02:32 PM

To answer the question..in diff POV
For upto spec cable, yes when fitted w appropriate MCB yes MCB will trip if the cable overloaded. Slow blow or instant trip depending on overload size. But anyhow this will work regardless slow blow or instant trip

For substandard cable..in the reverse scenario..if MCB sized accordingly to actual true max safe capacity of cable lousy spec then will protect as per above case.


If MCB was sized to untrue claimed spec per the fake labelling (which is normal procedure)..there is such a risk the cable melted before MCB slow blow happens (if the cable is really substandard aka fake shit).

This post has been edited by ceo684: Apr 27 2021, 02:55 PM


Attached thumbnail(s)

For 4P, 300mA cheap ma coz insensitive.
They sell the 300mA because still valid use for industry.
Not all RCD created equal

Should use the 30mA then up to par with current residential standard. 4P 30mA 63A usually cost almost double of the 4P 300ma.

Personally I'd still try to swap out to 30mA, safety first.

This post has been edited by ceo684: Apr 29 2021, 10:56 AM

Can consider changing to 30mA whole house RCD.
It is actually not expensive for the RCD itself especially if you are on single phase - RCD 30mA 63A 2P - [ABB / Hager within RM130; Schneider within RM110].


Whilst ST regulations say maximum of 100mA whole house and 30mA for 13A sockets.. this entails fitting TWO RCDs
Note the maximum.. it is not "exactly/identical" but "up to" meaning.
Meaning to save cost + fully compliant with the law, a 30mA whole house RCD will protect everything with one single RCD unit.

Actually all these are covered in the ST guidelines but then again from business perspective the end user may not be aware of the risks or just want cheapest solution that lights up so corners will have to be cut somewhere
 ST_Guidelines_For_Electrical_Wiring_2008_Edition.pdf ( 427.2k ) Number of downloads: 13


According to TS pic above TS is using 2.5mm² cables which should be fine for general sockets.
Also (presumably) looking at the nos. of MCBs in the whole DB box there should be enough individual circuits for the house not to exceed the 20A radial circuit floor area coverage of 20m² - if TS stay in 10 acre built-up home then that will be insufficient lah

Can get by with 300mA if the building is not a house but a factory/commercial building without 13A sockets
Ultimately still need at least one unit 30mA RCD to comply with mandatory requirements for residential.

Well.. once you go three phase it is one "increased cost factor" price element.. (over single phase)
Low amp (40A) three phase still cheap ..marginal increase from 63A single phase component
once you go higher amp (63A and above) on three phase .. another "increased cost factor" price element
high sensitivity component (w.r.t three phase) another "increased cost factor" price element

Hager
40A 4P the difference is RM127-145-166 between 300-100-30mA - for this case not much price difference, might as well go 30mA full
63A 4P the difference is RM153-199-250 between 300-100-30mA - for this case 60% diff

ABB FH204
40A 4P the difference is RM126-138-138 between 300-100-30mA - for this case not much price difference, might as well go 30mA full
63A 4P the difference is RM138-179-289 between 300-100-30mA - for this case it looks like double lah

This post has been edited by ceo684: Apr 29 2021, 01:51 PM

INDUCTIVE COUPLING
It is very normal (inductive coupling/voltage by inductance) as all the cables are run straight and in parallel over long distances (several meters) in close proximity (all stuffed into same conduit).
https://www.smar.com/en/technical-article/i...l-installations

WHY YOUR VOLTAGE INDICATOR LIGHTS UP ON NEARBY CABLES
Coz when the light cable is energised it will also have inductive coupling effect on nearby cables (ie fan cable).
The same effect also happens if you run the fan and test on the light cable.

This is partly why nobody install LAN cable in the same conduit next to power cables as the power cables will disturb the data transmission in unshielded UTP LAN cable.

INDUCTIVE COUPLING EFFECT USED IN NCV (Non Contact Voltage) DETECTION
The 230V AC voltage can be detected in non-contact voltage tester (as you can see even 8cm airgap here, the NCV detector lighted up)


Its made by Smart meter company
Not sure bout the app, but on mytnb web, click around there will be an Other Resources or similar link for smart meter portal

This post has been edited by ceo684: Apr 29 2021, 05:27 PM