Just to share from ST's (Suruhanjaya Tenaga) recommendations, here are a few installation details to take note of:

1. Cable/Power Supply for water heater should only come directly from the house's Distribution Board (DB). This power supply source cannot be shared, 1 supply direct to only 1 heater, and not tapped from the Aircond's socket or any other wall socket points.

2. To account for voltage drop, the cable length from DB to heater should not exceed 50m.

3. There should be at least 2 Residual Current Detector installed for protection, 1 nos 100mA for the mains (from TNB) into your DB, 1 more nos 10mA for the outgoing supply from your DB to the water heater. For the 100mA RCD, this is shared for your entire house. For the 10mA RCD, it should be 1 per heater, as per item no.1.

4. The cable/conductor size should be a minimum of 4mm2 for most instant water heaters in Msia (<5.0kW). This means that if you are using a PVC 3core cable (those grey cable with 3 in 1), it should be of the '56/0.30' size.

5. The Protective Earth should be a single run (green cable) as much as possible, and direct to your DB's Earth. That means you should minimise any 'sambung' cables, or to share the Earth with other power socket points in your house.

6. Lastly, there should be a certain IP rating to the socket used inside your toilet to connect the power supply to your water heater.

Hope this helps. The water heater is actually a very dangerous appliance which many people are not aware of. If installed simply, it is actually a time-bomb. Do pass these tips on to whoever who may need it, whether it is a new installation or an existing installation which may need correcting. Many houseowners are told by their electrical contractors or wiremen that so and so installation is correct or suitable but it might not really be the case.

This post has been edited by Jane's: Aug 8 2019, 02:52 PM