This is an electric on-demand hot water heater with two separate 240 V circuits feeding. The circuit on the left has to hot seven neutral, the circuit on the right has only the two hots connected. The housing to this unit is all metal and is connected to the bare wire/neutral.
There are stickers which say “this appliance must be earthed” inside the front panel(I assume this is the Chinese interpretation for “grounded”). I have a instant hot water in my home which had a similar setup where there was no dedicated ground wire but the one of my home has a plastic cover.
I have two questions: First, does this unit require a ground and is that what the stickers indicating when it says “earthed” or can the bare wire be used as both the neutral and the ground?
Second, shouldn’t the circuit on the left have its neutral/ground attached as well? I was taught by an electrician friend of mine years ago that conductors must always have voltage/amperage going both directions to prevent overheating.
Any help will be appreciated.