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ceo684
post Dec 20 2021, 02:24 PM

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QUOTE(un.deux.trois @ Dec 16 2021, 08:06 AM)
Power point already built in by developer.
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In that case not a rocket science..just drill 6 holes and hook up power directly only. As it doesnt involve pulling new wiring its pretty easy..any installer also can.
jutamind
post Dec 20 2021, 10:36 PM

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Can share where you get the RCCB and the box for RCCB?

QUOTE(ryansxs @ Nov 24 2021, 03:08 PM)
Fixed a 10mA RCCB before the water heater.
Since the wiring to the water heater is just at the ceiling, easy to add the RCCB there. Total damage is less than RM100.

user posted image
user posted image

Note: If you want to add yourself at home and not familiar with wirings, please get a qualified wireman.
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ryansxs
post Dec 20 2021, 11:01 PM

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QUOTE(jutamind @ Dec 20 2021, 10:36 PM)
Can share where you get the RCCB and the box for RCCB?
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Both from shopee.
The casing shipped from china.
The RCCB is local seller.
sijun
post Jan 5 2022, 03:15 PM

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Any recommendation for a centralized water heater, for 3 bathrooms but normally only max use 2 at once.

Looking at Joven JSH91 (about RM1K+)

Cannot afford Solar sad.gif
lacmac
post Jan 23 2022, 10:45 AM

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QUOTE(Selene Yeo @ Apr 19 2021, 11:36 PM)
If u don't want the hassle of covering the existing socket with plaster / cement, you can just replaced the plug and socket with CENTON Splash-Proof Water Heater Connector, u can easily find them on Shopee / Lazada. SIRIM approved.

Also, this CENTON Connector comes together with a 1 meter 4mm diameter cable from Fajar. Take note that no SIRIM-approved water heater brands (that I am aware of) comes with cable or 3-pin plug (for reasons stated by a few members above, because it is not allowed by SIRIM), so your installer have to supply a cable to connect your water heater to the power source. Might as well just get this CENTON Connector.

user posted image
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What is the point in installing this? The cable has 4mm wire, yet the storage heater wires (Centon Nautilus) which you connect to is 2.5mm


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ozak
post Jan 24 2022, 08:36 AM

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QUOTE(lacmac @ Jan 23 2022, 10:45 AM)
What is the point in installing this? The cable has 4mm wire, yet the storage heater wires (Centon Nautilus) which you connect to is 2.5mm
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Direct joint without the switch is more secure and ensures high current flow without heating up the joint.

Switch is not a good contact for high current. And the pin to the plug connection.
ceo684
post Jan 24 2022, 12:15 PM

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QUOTE(lacmac @ Jan 23 2022, 10:45 AM)
What is the point in installing this? The cable has 4mm wire, yet the storage heater wires (Centon Nautilus) which you connect to is 2.5mm
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The connector ensure a neat join safely, especially when the point in the wall is placed high up, like Micheal Jordan height where most ppl here will need a stepstool to turn on the WH..so it allows for the WH to be installed at a more reasonable height and safely.

Note that it is geared towards instant WH, not storage tank WH ya.

2.5mm is not follow ST regulation.

This post has been edited by ceo684: Jan 24 2022, 12:16 PM
lacmac
post Jan 24 2022, 03:14 PM

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QUOTE(ceo684 @ Jan 24 2022, 12:15 PM)
The connector ensure a neat join safely, especially when the point in the wall is placed high up, like Micheal Jordan height where most ppl here will need a stepstool to turn on the WH..so it allows for the WH to be installed at a more reasonable height and safely.

Note that it is geared towards instant WH, not storage tank WH ya.

2.5mm is not follow ST regulation.
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The storage heater will be placed above the ceiling of the shower. Where it will be plugged in using the standard WH plug which will also be above the ceiling. There is the main swit h outside the bathroom.

If 2.5mm is not following ST regulation, then Centon are at fault as they use 2.5mm inside their unit. No point fitting 4mm wire to a 2.5mm wire.

Personally I think it is OK to use the 3 pin plug as the unit is rated at 2500w so a 13amp plug should surfice.
ceo684
post Jan 24 2022, 03:50 PM

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QUOTE(lacmac @ Jan 24 2022, 03:14 PM)
The storage heater will be placed above the ceiling of the shower. Where it will be plugged in using the standard WH plug which will also be above the ceiling. There is the main swit h outside the bathroom.

If 2.5mm is not following ST regulation, then Centon are at fault as they use 2.5mm inside their unit. No point fitting 4mm wire to a 2.5mm wire.

Personally I think it is OK to use the 3 pin plug as the unit is rated at 2500w so a 13amp plug should surfice.
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That connector, is able to support all sort of instant WH, typically 3.xkW class (15-16A or so) AND 4.8kW class instant heaters (21A nominal).
4mm can do up to 32A.

For your case storage WH
power is small at 3.00kW
and the way storage WH is wired, its not using that connector.

ST regulation for WH require double pole switching (cut both L and N). 13A SSO only cut live hence not suitable. Plug connection also prone to overheat due to loose connections.
lacmac
post Jan 24 2022, 04:53 PM

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QUOTE(ceo684 @ Jan 24 2022, 03:50 PM)
That connector, is able to support all sort of instant WH, typically 3.xkW class (15-16A or so) AND 4.8kW class instant heaters (21A nominal).
4mm can do up to 32A.

For your case storage WH
power is small at 3.00kW
and the way storage WH is wired, its not using that connector.

ST regulation for WH require double pole switching (cut both L and N). 13A SSO only cut live hence not suitable. Plug connection also prone to overheat due to loose connections.
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At 2500w the amperage is roughly 10amps. A 13amp plug connection shouldn't overheat? Also if you connect a 4mm wire to the 2.5mm wire inside the unit any overheating will happen at the unit. Correct? However it should trip the breaker 1st.

ceo684
post Jan 24 2022, 06:56 PM

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QUOTE(lacmac @ Jan 24 2022, 04:53 PM)
At 2500w the amperage is roughly 10amps. A 13amp plug connection shouldn't overheat? Also if you connect a 4mm wire to the 2.5mm wire inside the unit any overheating will happen at the unit. Correct? However it should trip the breaker 1st.
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It should be a plug top that is heavy duty rated like MK646 or at least a proper plug top like MK650 AND a metal clad MK socket. The way some cheapo plug tops melt by itself even at 1800W due to cut corner construction is just apalling not to mention dangerous hence a fixed installation is recommended. And even a cheapo plug top has SIRIM sticker on it whistling.gif breaker only trip if exceed 20A for long enough time.

Remember Malaysia is Bolehland. C CURVE MCB thermal trip is so slow/ lax it only trips when you're halfway cooking the dish. Overseas B curve is used in SG, AU, UK in residential. B Curve u want to buy locally cannot find one.. need special order from RS or element14 rclxub.gif
stormer.lyn
post Jan 24 2022, 10:59 PM

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These are typical MCB trip curve for type B vs C from http://finolex.com/wp-content/uploads/2018...B-Catalogue.pdf

This defines the zones where the tripping occurs, ie, there is one for Thermal (slow) and Surge (fast). The X axis is the current input, and 1x, 2x, 3x, etc of the MCB rating. So a 10A MCB at 1x = 10A, 2x = 20A and so on.
user posted image
As you can see, surge tripping begins at 3x-5x for B curve, and 5x-10x for C curve.

Imagine that your lighting circuit has a B10 (B curve, 10A) MCB. The light shorts out and a current of 20A flows. Thermal tripping will happen, between the time of about 15 to 210 seconds.
user posted image
If your MCB were a C10, then the thermal trip will happen between 10 and 190 seconds. From the graphs, you can see that the thermal tripping is not significantly different between B and C curve MCBs.

Where there is significantly different is between where the curves start. 3-5 for B curve, and 5 - 10 for C curve. Let's take a 4x short circuit current.
user posted image
B curve trips between 0.015s to 30s, C curve between 1.5s - 15s

So how do you get past being unable to get B curve MCBs? The answer is you get a lower rated C curve MCB.
Taking the same example above, where the lighting shorts, and 4x (40A) current flows. B10 still trips between 0.015s - 30s, but if you use a C6 MCB (40/6=6.67 aka 40A is 6.67 times the rating of C6) your tripping time drops tremendously.
user posted image

A B20 MCB at 3x overload (60A) becomes 3.75x if you use a C16 MCB. Not the same, mind you, but more similar to each other. But a B10 at 3x overload, becomes a 5x when using a C6 which brings the exact same timings.
user posted image


This is actually why the wires you use are extremely important. Wires must be able to withstand the heating of a short circuit, until the MCB thermally trips. As you can see from the top of the Y axis, the value is in the hour range at low overload ~1.1x factor. Always see the Current Carrying Capacity of wires at 70°C (as wires heat up when carrying current) according to the proper standards. And as wires heat up, their CCC decreases. Edit to add : this is why wires are specified big, 4 mm² for water heaters. The wires may be hot, or embedded in concrete with no cooling, or many wires run together causing more heat in the wires. The wire in the water heater will have a more or less known temperature, so 2.5 mm² can be used by the manufacturer for the maximum current at the highest temperature they will reach.

In summary, B curve and C curve are only significantly different at the Surge, or Inrush current when starting inductive devices.

Hope this furthers the discussion. Any mistakes are my own. Please let me know so I may make corrections.

This post has been edited by stormer.lyn: Jan 24 2022, 11:07 PM
lacmac
post Jan 25 2022, 09:37 AM

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[quote=stormer.lyn,Jan 24 2022, 10:59 PM]
These are typical MCB trip curve for type B vs C from http://finolex.com/wp-content/uploads/2018...B-Catalogue.pdf

This defines the zones where the tripping occurs, ie, there is one for Thermal (slow) and Surge (fast). The X axis is the current input, and 1x, 2x, 3x, etc of the MCB rating. So a 10A MCB at 1x = 10A, 2x = 20A and so on.
user posted image
As you can see, surge tripping begins at 3x-5x for B curve, and 5x-10x for C curve.

Imagine that your lighting circuit has a B10 (B curve, 10A) MCB. The light shorts out and a current of 20A flows. Thermal tripping will happen, between the time of about 15 to 210 seconds.
user posted image
If your MCB were a C10, then the thermal trip will happen between 10 and 190 seconds. From the graphs, you can see that the thermal tripping is not significantly different between B and C curve MCBs.

Where there is significantly different is between where the curves start. 3-5 for B curve, and 5 - 10 for C curve. Let's take a 4x short circuit current.
user posted image
B curve trips between 0.015s to 30s, C curve between 1.5s - 15s

So how do you get past being unable to get B curve MCBs? The answer is you get a lower rated C curve MCB.
Taking the same example above, where the lighting shorts, and 4x (40A) current flows. B10 still trips between 0.015s - 30s, but if you use a C6 MCB (40/6=6.67 aka 40A is 6.67 times the rating of C6) your tripping time drops tremendously.
user posted image

A B20 MCB at 3x overload (60A) becomes 3.75x if you use a C16 MCB. Not the same, mind you, but more similar to each other. But a B10 at 3x overload, becomes a 5x when using a C6 which brings the exact same timings.
[url=https://pictr.com/image/BbE3qB][img]https://pictr.com/images/

Thank you for your explanation.
However I wonder about how you said:

"The wire in the water heater will have a more or less known temperature, so 2.5 mm² can be used by the manufacturer for the maximum current at the highest temperature they will reach"

unless those 2.5mm wires are specifically made to withstand higher temperatures, if the temperature exceeds their limit, for sure the 2.5mm wires inside the storage heater will melt.

If I was to install the centon smart plug with 4mm wires. It would look like this. 2.5mm wires from storage heater connected to 4mm wire on centon smart plug which is plugged into 2.5mm socket which leads to RCD 2.5mm to 4mm to 2.5mm

The storage heater amps is 10.41. Surely 2.5mm wire is suitable?

Or are you referring to water heaters, not storage heaters?
ceo684
post Jan 25 2022, 04:21 PM

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QUOTE(lacmac @ Jan 25 2022, 09:37 AM)
Thank you for your explanation.
However I wonder about how you said:

"The wire in the water heater will have a more or less known temperature, so 2.5 mm² can be used by the manufacturer for the maximum current at the highest temperature they will reach" 

unless those 2.5mm wires are specifically made to withstand higher temperatures, if the temperature exceeds their limit, for sure the 2.5mm wires inside the storage heater will melt.

If I was to install the centon smart plug with 4mm wires. It would look like this. 2.5mm wires from storage heater connected to 4mm wire on centon smart plug which is plugged into 2.5mm socket which leads to RCD 2.5mm to 4mm to 2.5mm

The storage heater amps is 10.41. Surely 2.5mm wire is suitable?

Or are you referring to water heaters, not storage heaters?
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tagging Selene Yeo
If hypothetically I am the mfg for the connector, whole house burn down, the connector did not cause the problem as its far from weakest link, then OK.
Also it doesn't make sense to launch two models one 4mm cable and one 2.5mm cable because the latter is contravening ST guidelines of 4mm. Then later the connector become weakest link then it become a liability issue.

2.5mm in device is designed for its heat output w.r.t enclosure and ambient temp. Its "homologated" across the device model design and if the appliance is catching fire by itself all the time on normal operation it should fail SIRIM immediately. Plus the heater is made as-new-unit so the cables inside have very little wear and tear.

2.5mm in conduit part (your point wiring) is the variable component, your house and my house different. And that is WCS with overfilled conduits, insufficient bend radius, insulation damaged from bad wire pulls and what not, without cooling, and lastly age of wires.. who knows your wiring could be 40 years old or more where red also turn pink on the insulation. Furthermore, likely to be installed by unqualified faux electrician. This is likely to be the more suspect portion IMO.

Water heaters are a generic term for (typically) an electric or gas powered device that heats up water.
For ease of discussion lets just split it to instant WH (hanging on walls) and the storage heater (that tank hidden in ceiling).

This post has been edited by ceo684: Jan 25 2022, 04:24 PM
lacmac
post Jan 25 2022, 04:35 PM

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QUOTE(ceo684 @ Jan 25 2022, 04:21 PM)
tagging Selene Yeo
If hypothetically I am the mfg for the connector, whole house burn down, the connector did not cause the problem as its far from weakest link, then OK.
Also it doesn't make sense to launch two models one 4mm cable and one 2.5mm cable because the latter is contravening ST guidelines of 4mm. Then later the connector become weakest link then it become a liability issue.

2.5mm in device is designed for its heat output w.r.t enclosure and ambient temp. Its "homologated" across the device model design and if the appliance is catching fire by itself all the time on normal operation it should fail SIRIM immediately. Plus the heater is made as-new-unit so the cables inside have very little wear and tear.

2.5mm in conduit part (your point wiring) is the variable component, your house and my house different. And that is WCS with overfilled conduits, insufficient bend radius, insulation damaged from bad wire pulls and what not, without cooling, and lastly age of wires.. who knows your wiring could be 40 years old or more where red also turn pink on the insulation. Furthermore, likely to be installed by unqualified faux electrician. This is likely to be the more suspect portion IMO.

Water heaters are a generic term for (typically) an electric or gas powered device that heats up water.
For ease of discussion lets just split it to instant WH (hanging on walls) and the storage heater (that tank hidden in ceiling).
*
The wiring should be ok as it's a new house, I've not even moved in yet.
The wires from the plug socket to the SH is only 6 inches. The wiring from the RCD to the socket
is 2 ft away.

As you said : "Also it doesn't make sense to launch two models one 4mm cable and one 2.5mm cable because the latter is contravening ST guidelines of 4mm. Then later the connector become weakest link then it become a liability issue"

This is what I don't understand, why have 2.5mm if the regulations say 4mm? Also 2.5mm is sufficient for 10.41amps.

I understand if the unit if 3500w + but not for 2500w.


ceo684
post Jan 25 2022, 05:14 PM

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QUOTE(lacmac @ Jan 25 2022, 04:35 PM)
The wiring should be ok as it's a new house, I've not even moved in yet.
The wires from the plug socket to the SH is only 6 inches. The wiring from the RCD to the socket
is 2 ft away.

As you said : "Also it doesn't make sense to launch two models one 4mm cable and one 2.5mm cable because the latter is contravening ST guidelines of 4mm. Then later the connector become weakest link then it become a liability issue"

This is what I don't understand, why have 2.5mm if the regulations say 4mm? Also 2.5mm is sufficient for 10.41amps.

I understand if the unit if 3500w + but not for 2500w.
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ST guidelines recommend 4mm to cover the long run from DB box to the heater. Votage drop is a problem because P=VI. I can increase substantially and cause unwanted heating.
This could be a long run if you stay in big house or longhouse.

Whereas inside the WH unit the wires are measured in inches i.e. very short so 2.5mm for that part is OK. It cant make a huge enough voltage drop.


This post has been edited by ceo684: Jan 25 2022, 05:15 PM
digitalz
post Jan 25 2022, 05:38 PM

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Quick random question. Anyone tried sigma water heater before?
stormer.lyn
post Jan 25 2022, 05:39 PM

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QUOTE(lacmac @ Jan 25 2022, 09:37 AM)
If I was to install the centon smart plug with 4mm wires. It would look like this. 2.5mm wires from storage heater connected to 4mm wire on centon smart plug which is plugged into 2.5mm socket which leads to RCD 2.5mm to 4mm to 2.5mm
*

WH = Water heater (instant type), SH = Storage heater (water tank type)
Suruhanjaya Tenaga specifies ALL types of water heaters to be wired with a minimum of 4 mm² cable. In your instance, there is no possibility for 2.5 mm² to become 4 mm², become 2.5 mm², if you are conforming to ST rules. In other words, the wiring from the DB right into the WH/SH must be 4 mm² minimum all the way, no matter if there is an RCCB in between, or RCBO, or switch, or whatever. If you don't conform to this, you don't conform to ST rules.

If you think you can use a 13A socket, or don't want to use the Centon connector (I don't, I make direct connections), or use 2.5 mm² cable, then you can but it is entirely your responsibility. People here are posting about what you should do following the rules, but you seem to want justification on why you shouldn't. Sorry, can't do that. Wires internal to the WH/SH does not need to conform to ST wiring rules, and ceo684's post repeated below explains why.

I've said "4 mm² minimum" twice. Wire selection actually has a criteria : At full current draw of the device 1. The wire can only reach a maximum of 70°C, and 2. The voltage drop across the length of the wire must be less than 10% of the supply voltage. If either fail, you need to increase the wire size. Dagnabbit, ninja'd by ceo684 laugh.gif

QUOTE(ceo684 @ Jan 25 2022, 04:21 PM)
tagging Selene Yeo
If hypothetically I am the mfg for the connector, whole house burn down, the connector did not cause the problem as its far from weakest link, then OK.
Also it doesn't make sense to launch two models one 4mm cable and one 2.5mm cable because the latter is contravening ST guidelines of 4mm. Then later the connector become weakest link then it become a liability issue.

2.5mm in device is designed for its heat output w.r.t enclosure and ambient temp. Its "homologated" across the device model design and if the appliance is catching fire by itself all the time on normal operation it should fail SIRIM immediately. Plus the heater is made as-new-unit so the cables inside have very little wear and tear.

2.5mm in conduit part (your point wiring) is the variable component, your house and my house different. And that is WCS with overfilled conduits, insufficient bend radius, insulation damaged from bad wire pulls and what not, without cooling, and lastly age of wires.. who knows your wiring could be 40 years old or more where red also turn pink on the insulation. Furthermore, likely to be installed by unqualified faux electrician. This is likely to be the more suspect portion IMO.

Water heaters are a generic term for (typically) an electric or gas powered device that heats up water.
For ease of discussion lets just split it to instant WH (hanging on walls) and the storage heater (that tank hidden in ceiling).
*
lacmac
post Jan 25 2022, 06:48 PM

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QUOTE(ceo684 @ Jan 25 2022, 05:14 PM)
ST guidelines recommend 4mm to cover the long run from DB box to the heater. Votage drop is a problem because P=VI. I can increase substantially and cause unwanted heating.
This could be a long run if you stay in big house or longhouse.

Whereas inside the WH unit the wires are measured in inches i.e. very short so 2.5mm for that part is OK. It cant make a huge enough voltage drop.
*
It's only 2ft length of wire to the DB box. Might even be shorter as the box is on the other side of the shower wall.
ceo684
post Jan 25 2022, 08:44 PM

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QUOTE(lacmac @ Jan 25 2022, 06:48 PM)
It's only 2ft length of wire to the DB box. Might even be shorter as the box is on the other side of the shower wall.
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If the whole length from DB box to the storage tank is <1m then 4mm it lah since loose cut 4mm mega kabel for 3x 1meter is not expensive at all (RM2.80/m).
Because its not worth the hassle of explaining to insurance adjuster if a fire occur and they are gonna wash hands by saying its not following the electricity regulations 1994.

This post has been edited by ceo684: Jan 25 2022, 08:45 PM

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