Water Heater (MCB and brands)
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 Dec 29 2023, 12:25 AM
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#1
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang   
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QUOTE(FyChai @ Dec 28 2023, 09:04 PM) Sorry I'm lost, I'm using C16 as photo, does it too high or low for the 42 kwh water heater? C16 mean for 16A right? ChatGPT ask me to get C25, salesman said C16 ok for it, so confusing. Appreciate for your reply. C16 OK for 3300W WH.  4200W WH pls run a new line (electrician required) with 6mmsq cable else you gonna burn down ur hse. Of coz salesman everything can, burn also not his place |
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Dec 29 2023, 12:30 AM
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#2
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang
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QUOTE(FyChai @ Dec 28 2023, 11:17 PM) I had read that post, inside said 25A MCB RCB, but other post said 10mA, so which one should I use? C10 or C25? Please do not confuse between RCD and MCB.MCB you have now is a C16 to safely allow up to 16A LOAD. RCD which you don't have now, and you will need, is a 10mA RCD rated to sense up to 25A, this is the bestest protection - https://shopee.com.my/ABB-F202-25-0.01-ELCB...1856.9133931062 or this also can, if budget is an issue https://shopee.com.my/Schneider-Easy9-25A-2...4033.3943044744 Failure to install a proper 10mA RCD will lead to unwanted outcome, usually death. https://www.straitstimes.com/singapore/cour...oroners-inquiry https://www.freemalaysiatoday.com/category/...ed-in-bathroom/ ---------- Since we're here, your existing installation is totally illegal, and is useless for human life protection. 3.5 RCDs and Direct Contact Shock Protection The use of RCDs with rated residual operating current of 30mA or less are recognised as additional protection against direct contact shock. Regulation 415.1.1 refers. Direct contact shock is the result of persons or livestock inadvertently making contact with normally live parts with one part of the body and, at the same time, making contact with earth potential with another part of the body. Under these circumstances, the resulting electric shock will be at full mains potential and the actual current flowing to earth will be of the order 230mA because of the relatively high body impedance involved. It has already been shown in Section 2.3 that currents as low as 40/50mA can result in electrocution. Read more here https://forum.lowyat.net/index.php?showtopi...ost&p=106857006 This post has been edited by ceo684: Dec 29 2023, 12:43 AM Attached thumbnail(s) 
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Dec 29 2023, 12:34 AM
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#3
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang
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QUOTE(Selene Yeo @ Dec 29 2023, 12:32 AM)  4.2kW instant water heater should only require 4mmsq cable, not 6mmsq cable, according to Suruhanjaya Tenaga's table above. If I am reading the table correctly. Selene Yeo liked this post
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Dec 29 2023, 12:49 PM
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#4
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang
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QUOTE(Zot @ Dec 29 2023, 09:03 AM) You have been running your current water heater which is rated 3.5kW – 5.5kW for so many years already and your wire probably a 4mm² wire. I think it should be just fine to just use the same wire. 30mA not 100mA. Otherwise still fail on the Final Circuit for 13A SSO 30mA regulation.The wire can carry 32A roughly if it is inside tubing or directly nailed on or inside the wall cement wall. Your 4.2kW water heater will max at 18.3A @230V. I would consider it as continuous load current. So, I would derate wire requirement. 1.25 x 18.3 = 22.875A which i still within the wire load capability. You need to install a 100mA RCD (not MCB as mentioned by ceo684. This is for safety against electrocution. You do not want any current more than 10mA run through your body if accidentally touch wire or if the water heater got leak current. You can put it on wall just before the 2 pole switch inside single breaker casing if you do not have space in main DB box. Regulation aside.. 100mA trips after the 50mA threshold..  Attached thumbnail(s) 
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Dec 29 2023, 12:53 PM
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#5
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang
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QUOTE(FyChai @ Dec 29 2023, 08:52 AM) The DB is ori set from developer, I just add on 3 MCB on left hand side for dry and wet kitchen. May I know is that call MCCB for my current 63A breaker? If I change to 100mA, do I need to upgrade or remain 63A? The quality of components used are questionable if they already installed C16 MCB. As per pic above, do I need to place 1 RCB for every floor? Or just for the cable which use for water heater? Sorry lots of questions, i need more knowledge before asking a electrician to visit again. Previous electrician came to check and never mention about the 300mA of breaker and RCB until I find it myself. Your scope of work: change the mains (entire house) RCD to 30mA. install a new 10mA RCD for EACH WH (water heater) circuit. You do not need a RCD for every floor. |
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Dec 29 2023, 06:31 PM
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#6
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All Stars
11,667 posts Joined: Jan 2003 From: Klang/Subang
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QUOTE(FyChai @ Dec 29 2023, 02:52 PM)  Do you mean this one change to 30mA? Remain 63A? May I know what type of breaker is this? RCCB? This is a RCD. The spec is 4P 63A 30mA (0.03A). Estimated barang only- RM2xx for a good one from ABB/Hager. https://shopee.com.my/ABB-FH204-63A-4P-300m...2787.3248905327 |
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