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This is a question about electrical safety in Japan. I know this isn’t a Japanese forum, but my Japanese isn’t up to much, and everyone I can ask either knows nothing about electrical safety or nothing about Japan.

I come from the UK, where every plug is three-pronged and ordinary consumers like me don’t have to think about matters like grounding.

Here in Japan, most plugs are two-pronged. Risky devices like washing machines and dishwashers come with an extra green and yellow ground wire bolted onto the back. In my 80s apartment there are a couple of power sockets with a little metal plate where I can attach a ground wire; one is in the place where you’d expect a refrigerator to go, and the other is for the washing machine. It seems that the builders didn’t anticipate other kinds of home appliance.

So now I have a dishwasher, and it’s nowhere near any of the grounding plates. But it is near the kitchen range, and the kitchen range has a couple of gas taps attached. I am vaguely aware that gas pipes should be grounded, so I considered connecting the ground wire to the sink, but on closer inspection, it appears that the gas taps and the sink do not make electrical contact -- a 1 inch ring of uPVC separates the two.

The pipe work is safely sealed away from incompetent amateurs like me, so I can’t start hunting for evidence of grounding work there. However, the kitchen range does appear to have electrical contact (through metal pipes) to a gas water heater just above the kitchen range. The gas water heater is, in turn, connected to one of the gas taps via what appears to be a rubber hose. I don’t see any other signs of grounding, and the water heater was professionally installed so, at first glance, this suggests that the kitchen range is grounded.

So, what should I do? Shall I just connect the dishwasher to the sink, or am I going to have to bite the bullet and run a long wire to the refrigerator’s ground plate?

Many thanks for taking the time to read this.

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The sink is not ground. If you ground to the sink, and then developed a ground fault. Touching the sink will give you a nasty surprise. –  Tester101 Mar 10 '12 at 13:42
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up vote 5 down vote accepted

You cant rely on the integrity of the ground/earth on the pipework of the sink. For all you know it could be connected to pvc piperwork further down. In the U.K all piperwork is meant to be cross bonded which is then taken to the earthing bar. However in Japan i am unsure if this is what is done. Regardless you should be earthing/grounding it back to the incoming supply. In alot of countries that use two pronged devices they are actually fed from centre tapped transformers or are double insulated devices. Either way they should not become dangerously live.

In short dont connect to the sink run it back to the earthing/grounding bar

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Many thanks! I’ll do that. –  Pitarou Mar 11 '12 at 5:37
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