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 RCCB for Water Heater

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babybaby1988
post Apr 19 2021, 09:55 PM

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QUOTE(halcyon27 @ Apr 8 2020, 10:23 PM)
Maybe talk to these guys as shown here.

Your intention is correct...layering electrocution protection
MCB 100ma electrical fire protection
Water heater circuit 30mA RCBO residual current breaker and overload protection (layman calls it rccb but technically it's rc+o breaker)
Heater appliance ELCB built in. Newer ones also have 10ma RCD.

Some may add 10mA at the heater master switch also for added protection due for hook on contact when electrocution caused spasms that the user is unable to let go of the energized device.

The reasonable protection principle is redundancy....in case even the protection circuitry fails over time, there is another along the circuit to back it up. Just don't overdo.

The other is to engage a qualified electrician to check the integrity of the circuit at water heater after installation. Or a renovation that touched the bathroom and may have perhaps involved the water heater. A checker auditing an installers work. Usually the head electrician will do that. You never know...and don't want to find out the shocking way.

Also look up isolator barriers which are now mandated for storage water heater installations. The company that produces them is called showertec. And also non metal type shower hoses.
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can anyone recommend an installer for external rccb ?

This post has been edited by babybaby1988: Apr 19 2021, 11:28 PM
babybaby1988
post Apr 19 2021, 11:26 PM

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QUOTE(ceo684 @ Apr 19 2021, 10:45 PM)
Well, it is supposed to be inside the DB box.
Any qualified electrician will be able to handle the installation of 10mA RCD.

Generally if theres enough space in the DB box for 2 modules ("fat RCD") then no problem to add it in, else may need to consider using slim 1 module RCBO instead. U can take a pic of the DB box and show us for better commentary. No need to open until can see wires. Just the user accesible portion will do.

There may be false tripping if your WH circuit is not dedicated circuit but running on looped (shared) neutral as the 10mA RCD is a highly sensitive device.
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attached is my current box, its messy as i requested my electrician to change all fuse mcb to trip mcb, but somehow my autogate and bell stop working and he cant seems to figure out how.

So i asked him to stop work and tmr another electrician will come.

So i told this new electrician i want RCCB outside toilet and i am not sure he understand what i want so he said he will come and see first


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babybaby1988
post Apr 20 2021, 02:50 PM

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QUOTE(ceo684 @ Apr 19 2021, 11:39 PM)
Oh dear. Best to get the new electrician to do complete overhaul change all the MCBs to one brand (ABB/Hager). The MCBs around RM7-8 bucks each only at the electrical store.

As you can see, between the taller ones and the shorter ones there are physical differences. This is a very dangerous situation as it is a loose connection (can catch fire) for the top row of short Hager fuse boxes.

Judging from the age of the whole setup, it is likely that the wires has broke internally for the one that powers your autogate (internal injury of the cable).

Normally we will advise user to turn off the questionable circuit until the electrician comes - but in this case there are alot of LIVE WIRES hanging around with masking tape as insulation  puke.gif - so please do NOT touch it at all
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Thanks ceo684, finally got someone to fix back everything and change the mcb.

I plan to pull new wires from dbbox since i have shared heater and ac on all three bedrooms upstairs.

always have to off ac before use heater. so far no issue, just troublesome.

Any electrician whom u can recommend or u able to do?
babybaby1988
post Apr 21 2021, 07:55 PM

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QUOTE(ceo684 @ Apr 20 2021, 06:34 PM)
Your new electrician should be able to handle?
Since new wiring (new set of LNE cables) being pulled it may make sense to procure the material yourself and ask him to come to install as labour only if agreeable and also it will save some cost lah.

Ideally, following ST guidelines, core scope of work will be
Pull a new set of 2.5mm² LNE cables for each AC unit
Pull a new set of 4.0mm² LNE for each WH unit
Add in C20 MCB for all the above circuits
Add in 10mA RCD to the DB box, one RCD for each WH circuit
Add in 20A double pole WH switch for each WH circuit outside bathroom
Add in 20A double pole switch for each aircon

Additional nice to haves:
Whether to conceal (need extensive hacking) or just run surface mounted PVC conduit (no need extensive hacking, minor hacking required) will be a price+aesthetic consideration.

Replace whole hse main incomer from switch fuse and old 100mA RCD - to new whole hse RCD 30mA + new whole house MCB (40/63A depending on existing cable size)
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Cos he doesnt do hack/conceal, only do casing sweat.gif sweat.gif

But i manage to find another electrician already, also prefer not to do hacking so i said will have to find some contractor to do hacking first

So i got quoted 3550RM without hacking for:-

a) install second DB at second floor
b) pull 3 wires for AC & switch
c) pull 3 wires for WH & switch
d) pull 1 wire for water pump & switch
e) pull 3 wires for socket

reasonable?
babybaby1988
post Apr 23 2021, 04:03 AM

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QUOTE(ceo684 @ Apr 22 2021, 11:30 PM)
roughly circa 2100 for the electricals; and the rest will be the hacking work.
Sounds about right.
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3550 is just for electrical, without hacking sweat.gif sweat.gif
babybaby1988
post Jun 9 2021, 05:51 PM

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QUOTE(ceo684 @ Apr 19 2021, 11:39 PM)
Oh dear. Best to get the new electrician to do complete overhaul change all the MCBs to one brand (ABB/Hager). The MCBs around RM7-8 bucks each only at the electrical store.

As you can see, between the taller ones and the shorter ones there are physical differences. This is a very dangerous situation as it is a loose connection (can catch fire) for the top row of short Hager fuse boxes.

Judging from the age of the whole setup, it is likely that the wires has broke internally for the one that powers your autogate (internal injury of the cable).

Normally we will advise user to turn off the questionable circuit until the electrician comes - but in this case there are alot of LIVE WIRES hanging around with masking tape as insulation  puke.gif - so please do NOT touch it at all
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btw can we change the neutral and live for rccb?

The electrician already changed the whole DB Box and mcb but didnt change the RCCB cos he said still can use but still charged me full sum cry.gif .

I just ok that time, but now i bought another hager RCCD and think just install myself.

The new RCCB stated that top left no. 1 is live but my old RCCB the top right is live instead and the wire not long enough if wanna switch.
babybaby1988
post Jun 9 2021, 09:06 PM

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QUOTE(ceo684 @ Jun 9 2021, 08:27 PM)
You need to plan out how to reposition it. When there is limitation of wire length, this becomes tricky.
I've done replacement of DB for such hangmen tight wires that it may require some creative placement (to ensure everything can be connected).
For the wiring that came with the house.. that one no comment la can't do much; but for new wiring enough slack inside the DB box is important so you can configure accordingly.

Not sure how the NEW DB (current condition) look like but from the OLD BOX you can isolate the whole house off by disabling the fuse marked with Danger High Voltage (pull out the fuse and put it safely away on a table).
The incomer will be a problem to shut off but if you can shut off the whole house using the fuse (pull out) then you can work on the downstream components AFTER it.

Your new RCCB (30mA) can replace the existing one (i.e. second module) of the OLD BOX pic AFTER you have isolated the power.

Ref OLDBOX2 pic:
Busbar and 16mm² mega kabel pigtailsin the correct RED/BLACK colours can be purchased as loose cut (by meter).. LINK (Loose cut 16mm)
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Oh looks like my old setup the live is on RCCB top left, in my new setup (see attached pic), its on top right, so it means no issue to switch from left to right?


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babybaby1988
post Jun 11 2021, 12:42 AM

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QUOTE(ceo684 @ Jun 10 2021, 12:13 AM)
Whoever did this should be banned from working with electricity.  bruce.gif
The original (OLD FUSE) is 40A (sized for 10mmsq cable). Cannot suka suka replace with 63A breaker without changing ALL the wire to 16mmsq.
Should be fitted with C40 (NOT C63). 🔥🔥🔥🔥🔥 risk - cable all burn but the master MCB will not trip.."haven't overload >63A mah!"  shocking.gif

[attachmentid=10907235]

You can park the new RCD at the far right and just extend with new pigtails.
[attachmentid=10907252]
[attachmentid=10907253]
I see the new one also 100mA  whistling.gif Should return it and request to change it to a 30mA RCD instead as 100mA whole house is NOT up to code.
A single phase 40A 30mA RCD is not expensive. It make a world of difference between a 30mA or 100mA if there is a fault situation passing thru a human.
For further reading can see BEAMA (UK/BS standards) on RCDs. [attachmentid=10907254]

Only in Msia lives are cheap- we still sell 100mA and 300mA openly  shakehead.gif
Unmodified file rotated for easier viewing
[attachmentid=10907236]
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Hmm already buried all the wires into wall can the electrician uncle just pull the cable out without hacking?

I was thinking about 30mA RCD too but when he tried to install a 10mA RCD at the water heater plug downstairs, it keeps tripping. The plug point has looping (to another 4 sockets which i am not using except for a socket for a hood) which causes the tripping according to him. So to be safe i thought just used back the original 100mA since no tripping issue.

The electrician also install new DB upstairs (as attached). Anything i should ask him to change besides to change the 10mm to 16mm? The water heater cable he is using 2.5mm instead and he said trust him no issue one even after i show him the ST guidelines, i suppose should be ok right since my water heater is only 15amp. Not an easy uncle to deal with, even after i bought 10mA RCD and asked him to install, he refuses saying ppl will laugh at me. Only agreed after i showed him the Electricity Regulations. shakehead.gif shakehead.gif


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babybaby1988
post Jun 11 2021, 03:07 PM

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The cutout fuse already blown once when I tried to plug in a old computer, so TNB came and changed to new one at 63A

So i should just use back 40A should be enough ? Change everything to 40A since my wiring all is 10mm to the second DB also
babybaby1988
post Jun 19 2021, 02:13 PM

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QUOTE(ceo684 @ Jun 11 2021, 03:39 PM)
Normally, a fuse is sacrificial i.e. rated lower than the cable to protect the cable from burning up.
The other way, cable will burn up first to protect a higher rated fuse from blowing.

The TNB to main DB (incomer) is 10mm also?

Having four water heaters on at the same time is 16Ax4, without adding on anything else. Upsizing fuse need the cable to be upsized accordingly as well.
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Tnb to main is 16mm at least I think.

Anyway I asked my electrician to change to 40a main switch and 40a rccb 0.03A. But even with full load of 51a tested using clamp meter, the thing doesnt trip? Something wrong ah? But the cable very hot though, almost 45 degree celcius compared to ambient of just 28 degree
babybaby1988
post Jun 19 2021, 03:12 PM

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QUOTE(ceo684 @ Jun 19 2021, 02:35 PM)
The main switch need to be C40 MCB for it to trip on OVERCURRENT FAULT exceeding 40A.
Note: Just plain switch (isolator) without OVERCURRENT protection (ie No MCB function) does nothing to protect for OVERCURRENT.

When will MCB Slow Trip
In this case 51A > 40A its a sustained overload (MINOR OVERCURRENT FAULT) and it should "slow trip" using thermal trip within few mins.
‐-----
When will MCB Fast/instant Trip
(It will do a "fast trip" on the magnetic trip only if there is a SHORT CIRCUIT/MAJOR OVERCURRENT FAULT).

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RCD working principle is DIFF from MCB

For the 0.03A RCD yes this will be instant trip for CURRENT IMBALANCE (LEAKAGE PROTECTION).
The 40A on this unit is an indicator on how much total current can be safely monitored..but this RCD does NOT & will NOT trip in case of OVERCURRENT (which is MCB job).

RCD only measure "I-in = I-out + (tolerance of loss x up to 0.03A)". If the loss x higher than 0.03 (eg 0.032A) it will trip because "something is missing somewhere".
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Ahh no wonder.

QUOTE
The 40A on this unit is an indicator on how much total current can be safely monitored..


Urmm lets say now my current usage now is 50A and then there is a leakage of 0.1A somewhere, will this 40A 0.03A RCCB trip?
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