Just to clarify, you are using a storage water heater correct? Not an instant water heater.

If it is a storage water heater, then FYI storage water heaters do not have a built-in circuit breaker like instant water heaters. So they have to rely on the DB box circuit breaker. BUT if your storage water heater is not grounded / no earth connection, no matter how good quality your circuit breaker is, the circuit breaker will not trip when there is a current leakage, and u will be electrocuted.

Hence why SIRIM / Suruhanjaya Tenaga now set a new guideline for storage water heaters to come with Isolation Barriers placed at both the storage water heaters' inlet and outlet water connection. Most SIRIM certified storage water heater brands already complied to this guideline, and some brands even took the extra safety effort to pre-install the isolation barriers on the heater, such as CENTON, which is extra good, considering some inexperienced installers will missed out installing the Isolation Barriers if they are not pre-installed on the heater out-of-the-box.

Isolation Barriers are simple devices that elongate any current flow from the storage water heater to users, so any current flow (if there is) will barely reach the users. So in your case where there is an unfortunate current leakage because of the lack of earthing, if your storage water heater is pre-installed with Isolation Barriers, the Isolation Barriers will protect u from electrocution to a certain extend. But every device has a lifespan as well, so u will probably be protected until the lifespan of the Isolation Barriers ended. So don't just rely on the Isolation Barriers to protect u. Installation and earthing connection has to be correct in the first place.

Basically just a safety tip for u, if your storage water heater do not have Isolation Barriers pre-installed, u are advised to install them.

Better get plumbers who know how to install storage water heaters to do it for u. At the inlet, u will need to connect it to the pressure relief valve too (water source piping > pressure relief valve > isolation barrier > storage water heater's inlet).

Yes it looks like the one in your picture, but better purchase from the storage water heater's brand distributor so that u get more assurance that it is a confirm fit.

Suruhanjaya Tenaga recommends Isolation Barriers to be installed at both inlet and outlet. It is always better to be safe than sorry.