Follow the contractor advise.

This point look dangerous and no earth wire.

It is better to direct the wire into the heater instead a wall socket. With a switch outside the bathroom.

Not OK.

No earth wire like ozak said. So any good WH will not operate because if there is a short or leakage, the current cannot flow to earth but it just goes through the path of least resistance (the poor guy or gal taking bath).

Then the aftermath will come out in the newspapers https://www.nst.com.my/news/nation/2020/08/...e-electrocution

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So to prevent that from happening, a full 3 wire dedicated LNE from DB box is the right solution. And a 10mA RCD or RCBO must be fitted in. Its not that expensive for a decent one from Schneider - https://www.lazada.com.my/products/easy9-rc...APtevD&search=1 - about RM128 or so. ABB and Hager are good too but costs more.

Cable used should be mega kabel or caramay cable - min 2.5mm for all three. There are a lot of fake cable selling for half the price but they present a fire risk as one water heater is easily two and a half aircond units' consumption. Aircon 1hp only use 6A.. water heater anywhere from 14A-16A depends on wattage so one cannot skimp on good cables.

That 15A round pin plug socket is also running very close to redline for a 3300W heater and should NOT be used for a 3600W heater.

This is typical load amps for a 3300W heater:

[attachmentid=10592833]
Result of undersized cable + joinery that should NOT be there (ie. run a full direct cable from DB into WH with zero joinery in between):
[attachmentid=10592829]

[attachmentid=10592830]

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